- Email: [email protected]
p16 expression in follicular dendritic cell sarcoma: a potential mimicker of human papillomavirus–related oropharyngeal squamous cell carcinoma
p16 expression in follicular dendritic cell sarcoma: A potential mimicker of HPV-related oropharyngeal squamous cell carcinoma Lingxin Zhang MD, Chen Yang MD, James S. Lewis Jr MD, Samir K. El-Mofty DMD, PhD, MS, Rebecca D. Chernock MD PII: DOI: Reference:
S0046-8177(17)30177-6 doi: 10.1016/j.humpath.2017.05.019 YHUPA 4239
To appear in:
Human Pathology
Received date: Revised date: Accepted date:
29 March 2017 12 May 2017 17 May 2017
Please cite this article as: Zhang Lingxin, Yang Chen, Lewis Jr James S., El-Mofty Samir K., Chernock Rebecca D., p16 expression in follicular dendritic cell sarcoma: A potential mimicker of HPV-related oropharyngeal squamous cell carcinoma, Human Pathology (2017), doi: 10.1016/j.humpath.2017.05.019
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT
T
p16 expression in follicular dendritic cell sarcoma: a potential mimicker of HPV-related oropharyngeal squamous cell carcinoma Lingxin Zhang, MD; aChen Yang, MD; b,cJames S. Lewis Jr, MD; a,dSamir K. El-Mofty, DMD, PhD, MS; a,dRebecca D. Chernock, MD
RI P
a
a
Rebecca D. Chernock, MD Washington University School of Medicine Campus Box 8118 660 S. Euclid Ave St. Louis, MO 63110 Phone: 314-362-0101 Email: [email protected]
AC
CE
PT
Correspondence:
ED
MA
NU
SC
Department of Pathology and Immunology, Washington University School of Medicine, 660 S Euclid Ave, St. Louis, MO, USA, 63110 b Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, 1211 Medical Center Dr, Nashville, TN, USA, 37232 c Department of Otolaryngology, Vanderbilt University Medical Center, Nashville, TN, USA, 37232 d Department of Otolaryngology Head and Neck Surgery, Washington University School of Medicine, 660 S Euclid Ave, St. Louis, MO, USA, 63110
Running tittle: p16 in follicular dendritic cell sarcoma
Conflicts of interest and funding disclosures: The authors have no conflicts of interest or sources of support to disclose. This research did not receive any specific grant from funding agencies in the public, commercial or not-for-profit sector.
1
ACCEPTED MANUSCRIPT Summary Follicular dendritic cell sarcoma is a rare mesenchymal neoplasm that most commonly occurs in cervical lymph nodes. It has histologic and clinical overlap with the much
T
more common p16-positive human papillomavirus (HPV)-related squamous cell carcinoma of
RI P
the oropharynx which characteristically has nonkeratinizing morphology and often presents as an isolated neck mass. Not surprisingly, follicular dendritic cell sarcomas are commonly
SC
misdiagnosed as squamous cell carcinoma. Immunohistochemistry is helpful in separating the
NU
two entities. Follicular dendritic cell sarcoma expresses dendritic markers such as CD21 and CD23 and is almost always cytokeratin negative. However, in many cases of HPV-related
MA
oropharyngeal carcinoma, only p16 immunohistochemistry as a prognostic and surrogate marker for HPV is performed. p16 expression in follicular dendritic cell sarcoma has not been
ED
characterized. Here, we investigate the expression of p16 in follicular dendritic cell sarcoma and
PT
correlate it with retinoblastoma protein expression. A pilot study of dendritic marker expression in HPV-related oropharyngeal squamous cell carcinoma was also performed. We found that 4 of
CE
8 sarcomas expressed p16 with strong and diffuse staining in 2 cases. In 2 of the 4 cases, p16
AC
expression corresponded to loss of retinoblastoma protein expression. Dendritic marker expression (CD21 and CD23) was not found in HPV-related oropharyngeal squamous cell carcinomas. As such, positive p16 immunohistochemistry cannot be used as supportive evidence for the diagnosis of squamous cell carcinoma as strong and diffuse p16 expression may also occur in follicular dendritic cell sarcoma. Cytokeratins and dendritic markers are critical in separating the two tumor types.
Keywords: p16 immunohistochemistry; human papillomavirus; follicular dendritic cell sarcoma; nonkeratinizing; squamous cell carcinoma; oropharyngeal
2
ACCEPTED MANUSCRIPT 1. Introduction Follicular dendritic cell sarcoma is a rare, low-grade mesenchymal neoplasm initially
T
described by Monda and colleagues in 1986 [1]. The tumor is thought to originate from the
RI P
follicular dendritic cell which is a part of the innate immune system, primarily playing a role in antigen presentation, and located mainly in the germinal centers of lymphoid follicles [2]. As
SC
such, lymph node involvement, especially cervical, is most common [3]. Follicular dendritic cell
NU
sarcomas may also occur at a wide variety of extranodal sites including the oropharynx, neck soft tissue, parapharyngeal space, thyroid, liver, kidney and axial skeleton, among others [3–6]. A
MA
very rare inflammatory pseudotumor-like variant that occurs predominantly in the liver and spleen is Epstein-Barr virus (EBV) driven but conventional follicular dendritic cell sarcomas are
ED
not [7]. Middle-aged adults of both genders are mainly affected and surgery is the mainstay of
free survival of 34% [4].
PT
therapy. A pooled analysis of 97 patients showed a 5-year overall survival of 81% and disease-
CE
The histologic diagnosis of follicular dendritic cell sarcoma is challenging for several
diagnosis.
AC
reasons. First, it is a rare tumor type and thus may not be considered initially in the differential Further, there are several morphologic mimics including squamous cell or
undifferentiated carcinoma, meningioma and even paraganglioma, all of which are more common, and therefore may be given more consideration at the time of diagnosis. In fact, greater than 50% of follicular dendritic cell sarcomas are initially misdiagnosed as other entities, the majority as either carcinoma or meningioma [8–11]. Misdiagnosis as human papillomavirus (HPV)-related oropharyngeal squamous cell carcinoma (SCC) is of particular concern, given the significant clinical as well as histologic overlap with follicular dendritic cell sarcoma. HPV-related oropharyngeal SCCs are much more
3
ACCEPTED MANUSCRIPT common and have been increasing in incidence over the past several decades [12]. Just as follicular dendritic cell sarcomas most commonly arise in cervical lymph nodes of middle-aged
T
adults, approximately one-third of HPV-related oropharyngeal SCCs also present as an isolated
oropharynx [13-15].
RI P
neck mass, typically in middle-aged to older adults, without an obvious primary tumor in the In addition, follicular dendritic cell sarcomas may also occur in the
SC
oropharynx, especially the tonsils, where most HPV-related SCCs originate [5,16].
19].
NU
HPV-related oropharyngeal SCCs are typically, but not exclusively, nonkeratinizing [17Nonkeratinizing SCCs share many morphologic features with follicular dendritic cell
MA
sarcomas. Like follicular dendritic cell sarcoma, nonkeratinizing SCC is composed of oval to spindled cells with indistinct cell borders and indistinct nucleoli [17,18]. Infiltrating lymphocytes
ED
are usually present in both as well. Distinguishing histologic features include the presence of
PT
focal squamous maturation or keratin production and nested to ribbon-like growth in nonkeratinizing SCC versus fascicular to storiform growth and intranuclear pseudoinclusions in
CE
follicular dendritic cell sarcoma [7,17,18]. Mitotic activity is usually higher in SCC. However,
AC
these differentiating features may not be well represented on biopsy material or may not be obvious to a pathologist who is not familiar with both entities. Immunohistochemistry is useful in separating the two since follicular dendritic cell sarcomas are almost always cytokeratin (but not epithelial membrane antigen) negative and nonkeratinizing SCCs are cytokeratin positive [7]. Additionally, follicular dendritic cell sarcomas express dendritic markers (CD21, CD23 and CD35) and, while dendritic marker expression has not been investigated in nonkeratinizing SCC, it is unlikely to be present. However, in many cases of oropharyngeal SCC (and their metastases presenting as an unknown primary in the neck), p16 immunohistochemistry as a prognostic marker and surrogate for HPV
4
ACCEPTED MANUSCRIPT may be the sole immunostain performed. In fact, p16 is now recommended by the American Joint Committee on Cancer (AJCC) as the preferred method of HPV testing in oropharyngeal
T
SCCs and metastases of unknown primary in the neck [20]. p16 expression in follicular dendritic
RI P
cell sarcoma has not be fully elucidated but there is some indication that it may be present in a subset. Recently, Griffin et al (2016) found Retinoblastoma (RB1) inactivation (which could
SC
theoretically lead to p16 overexpression) in several follicular dendritic cell sarcomas [21].
NU
Here, we characterize the extent and pattern of p16 expression by immunohistochemistry in a series of follicular dendritic cell sarcomas, as p16 expression in follicular dendritic cell
MA
sarcoma could be a potential pitfall leading to an erroneous diagnosis of HPV-related nonkeratinizing oropharyngeal SCC. In addition, we perform a pilot study of CD21 and CD23
ED
expression in HPV-related nonkeratinizing oropharyngeal SCC to exclude the possibility of
AC
CE
2. Materials and Methods
PT
aberrant dendritic marker positivity in this tumor type.
2.1. Patients and samples
Human subject materials were utilized according to the guidelines set by the Human Studies Protection Office at Washington University in St. Louis and at Vanderbilt University with a waiver of consent. All follicular dendritic cell sarcomas with material available for review were retrospectively retrieved from the Pathology Department files for p16 and retinoblastoma protein (pRB) immunohistochemistry and EBV-encoded small RNA (EBER) in situ hybridization (ISH) for EBV. Cases were reviewed by 3 study authors (LZ, CY, RDC) to
5
ACCEPTED MANUSCRIPT confirm the diagnoses. Diagnostic inclusion criteria included: typical morphology (oval to spindled cells often forming fascicles with indistinct cell borders and infiltrating lymphocytes) as
T
described in the current World Health Organization Classification of Tumours of Haematopoietic
RI P
and Lymphoid Tissue, positivity for at least one dendritic marker, and absence of cytokeratin expression [7]. Immunohistochemistry, including dendritic markers and cytokeratins, was
NU
were extracted from the electronic medical records.
SC
performed as part of the routine diagnostic work-up in all cases. Demographic and clinical data
Ten representative nonkeratinizing SCCs of the oropharynx from surgically resected
MA
specimens were selected from the Washington University Pathology Department files for dendritic marker immunohistochemistry (CD21 and CD23), all of which were known to be p16-
ED
positive by immunohistochemistry (≥ 75% nuclear and cytoplasmic staining of at least moderate
PT
intensity) performed routinely in clinical practice as a prognostic marker and surrogate for HPV. Exclusion criteria included: tumors measuring < 1 cm (to avoid tissue depletion) and prior
CE
intraoperative frozen section analysis or obscuring thermal/cautery artifact, which may interfere
AC
with tumor immunogenicity.
2.2. Immunohistochemistry
Immunohistochemistry utilized formalin-fixed paraffin-embedded tissue cut at 4 µm sections and floated onto charged slides. Immunohistochemistry for p16 (E6H4 clone, CINtec; Ventana Medical Systems, Inc., Tucson, AZ), CD21 (2G9 clone; Cell Marque, Rocklin, CA) and CD23 (SP23 clone; Ventana Medical Systems, Inc., Tucson, AZ) was performed on a Ventana Benchmark automated immunostainer (Ventana Medical Systems, Inc., Tucson, AZ) by standard
6
ACCEPTED MANUSCRIPT protocols with adequate controls. Antigen retrieval, standard on the machine, utilized the Ventana Ultra CC1, EDTA-Tris pH 8.0 solution. Immunohistochemistry for pRB was performed
T
by NeoGenomics (G3-245 clone; BD Bioscience, San Diego, CA) on a Bond-III Autostainer
RI P
(Leica Biosystems Inc., Buffalo Grove, IL) by standard protocols with adequate controls. Antigen retrieval utilized Leica Bond Epitope Retrieval solution 2 (EDTA based buffer, pH 9.0).
SC
p16 immunohistochemistry was characterized by percent of nuclear and cytoplasmic
NU
staining as well as the intensity (weak, moderate or strong). p16 immunohistochemistry was also recorded as positive or negative according to established criteria for oropharyngeal SCC: ≥ 75%
MA
nuclear expression of at least moderate intensity [20]. pRB immunohistochemistry was interpreted as percent loss of nuclear staining in tumor cells with adequate positive internal
ED
control staining of non-neoplastic tissues. For the dendritic markers CD21 and CD23, percent of
PT
cells with cytoplasmic staining and intensity (weak, moderate or strong) was recorded.
AC
RDC).
CE
Interpretation of the immunohistochemical stains was performed by three study authors (LZ, CY,
2.3. In situ hybridization
ISH for EBER was performed on formalin-fixed, paraffin-embedded 4-μm tissue sections using a I View Blue Plus Detection Kit (Ventana Medical System). The assays used the Ventana INFORM EBER probe. Staining was in a totally enclosed system and was performed according to the manufacturer's instructions with adequate controls. Ventana Red Counterstain II (Ventana Medical System) was used. Positive staining was identified as blue nuclear dots. Any definitive
7
ACCEPTED MANUSCRIPT nuclear staining in the tumor cells was considered positive. Cases were classified in a binary
T
manner as either positive or negative by three study authors (LZ, CY, RDC).
RI P
3. Results
NU
SC
3.1. Clinical and pathologic features of follicular dendritic cell sarcoma cases
Eight cases of follicular dendritic cell sarcoma were identified from the Pathology
MA
Department files, 6 from Washington University in St. Louis and 2 from Vanderbilt University (Table 1). The mean age of the patients was 43.5 years (range 29 to 62 years) with a male to
ED
female ratio of 3:5. Four tumors (50%) were from the head and neck region: 1 arose in a cervical
PT
lymph node, 1 in the tonsil, 1 in the parapharyngeal space and 1 in the nasopharynx. The tumors had morphologic features typical of follicular dendritic cell sarcoma including oval to spindled
CE
nuclei with small to indistinct nucleoli, indistinct cell borders, and infiltrating lymphocytes. All
AC
cases were positive for the dendritic marker CD21 and negative for at least one cytokeratin. Additional dendritic markers were performed in a subset as part of the initial diagnostic evaluation. Five of 6 cases tested were CD35 positive and 3 of 4 were CD23 positive. Representative histologic images are shown in Fig.1. All patients were treated with surgical resection. Four received adjuvant chemotherapy and 2 radiotherapy. Three patients developed metastases, 1 of whom underwent successful resection of the metastasis and was free of disease at last follow-up 16 years after initial diagnosis. The other 2 patients with metastases are alive with disease at last follow-up. The
8
ACCEPTED MANUSCRIPT remaining 6 patients were disease-free at last follow-up. The median follow-up time was 3.5
T
years (range 3 months to 16 years).
RI P
3.2. p16 and pRB expression in follicular dendritic cell sarcomas
SC
Immunohistochemistry results are detailed in Table 1. Four (50%) of the follicular
NU
dendritic cell sarcomas showed p16 expression. Applying the criteria for p16 positivity established in oropharyngeal SCC (≥ 75% nuclear expression of at least moderate intensity), 2
MA
cases were p16 positive with strong staining in 100% of cells in one case and moderate staining in 80% of cells in the other[20]. Although nuclear staining was considered sufficient for
ED
positivity, all cases had both nuclear and cytoplasmic staining. One case that had p16 expression
PT
did not meet the oropharyngeal SCC criteria for positivity because the extent of staining was 60% (≤ 75%) and the other case because there was variable intensity of the staining (weak to
CE
strong) even though 80% of cells were positive. The staining patterns in both of these cases
AC
would be considered equivocal, if observed in oropharyngeal SCC as surrogacy for HPV [22]. Of the 4 cases with p16 expression, 2 showed loss of pRB expression by immunohistochemistry. Areas of pRB loss were nearly entirely restricted to areas of p16 expression. Representative images of p16 expression and pRB loss are shown in Fig. 2.
3.3. EBV in follicular dendritic cell sarcoma
9
ACCEPTED MANUSCRIPT None of the tumors had a dense inflammatory infiltrate characteristic of the inflammatory pseudotumor-like variant of follicular dendritic cell sarcoma, which is an EBV-driven tumor.
RI P
T
Furthermore, all tumors were negative for EBV by EBER ISH.
3.4. CD21 and CD23 dendritic marker expression in p16-positive (HPV-related)
NU
SC
nonkeratinizing oropharyngeal SCCs
A pilot study of dendritic marker expression in p16-positive (HPV-related)
MA
nonkeratinizing oropharyngeal SCC was undertaken. Dendritic markers CD21 and CD23 were negative in all 10 cases. Thus, aberrant dendritic marker expression was not observed in
ED
nonkeratinizing oropharyngeal SCC. Representative images of the nonkeratinizing SCCs are
CE
4. Discussion
PT
shown in Fig. 1 and demonstrate the morphologic overlap with follicular dendritic cell sarcoma.
AC
p16 is a tumor suppressor protein encoded by the CDKN2A gene located on chromosome 9p21. When bound with cyclin dependent kinase (CDK) 4 and 6, p16 blocks their interaction with cyclin D1, which in turn keeps pRB in a hypophosphorylated state and prevents cell-cycle progression through E2F1 transcription factor repression [23]. Although both function in concert as tumor suppressors by maintaining cellular senescence, pRB also paradoxically negatively regulates p16 [24]. Thus, loss of pRB expression often leads to p16 overexpression. While a wide variety of human tumors harbor genetic alterations that lead to p16 inactivation (gene mutation, deletion or hypermethylation), a smaller but growing number of tumors overexpress p16, which is often, but not always, a consequence of pRB mutation or loss
10
ACCEPTED MANUSCRIPT of function releasing p16 from pRB-mediated inhibition [24–27]. One such unique example of the latter is in HPV-driven SCCs.
HPV oncoproteins E6 and E7 induce malignant
T
transformation by binding to and inactivating tumor suppressor proteins p53 and pRB,
RI P
respectively [24]. Virus-mediated loss of pRB function leads to high levels of p16 expression in HPV-related SCCs of the head and neck and anogenital region [24]. Detection of p16
SC
overexpression by immunohistochemistry has emerged as a robust surrogate marker of HPV-
[28,29].
NU
related SCC in the oropharynx that is both sensitive (>95%) and specific (>90%) in this setting In fact, p16 immunohistochemistry has been endorsed by the AJCC as the
MA
recommended HPV-testing method that should be performed in all oropharyngeal SCCs [20]. Importantly, the p16 staining pattern must be moderate to strong, diffuse (≥ 75% of cells) and
ED
including nuclear positivity, although staining is almost always both nuclear and cytoplasmic
PT
[20]. Determining tumor HPV status in oropharyngeal SCCs is critical because HPV-related oropharyngeal SCCs have a significantly better prognosis compared to HPV-negative tumors
CE
[30]. As a result, patients are often stratified by tumor HPV status when determining clinical trial
AC
eligibility and may receive different treatment outside the context of a trial in the near future. The difference in clinical behavior is now also reflected in the separate staging systems for p16positive (HPV-related) versus p16-negative (HPV-unrelated) oropharyngeal SCC in the new 8th edition of the AJCC Cancer Staging Manual [20]. The high specificity of p16 for HPV-related SCC in the oropharynx is in part due to the high prevalence of HPV-related tumors, accounting for well over half of SCCs in the United States, at this site [12]. The specificity of p16 for HPV-related SCC declines outside of the oropharynx where the prevalence of HPV-related SCC is much lower. This is because there is a growing list of other tumors that demonstrate strong and diffuse p16 expression through HPV-
11
ACCEPTED MANUSCRIPT independent mechanisms [25–27,31,32]. HPV-negative SCCs of various sites occasionally show extensive p16 overexpression with some of the highest rates so far (20% or more) documented in
T
cutaneous head and neck SCCs [31,32]. Neuroendocrine tumors, especially high grade ones such
RI P
as small cell carcinoma, frequently show strong and diffuse p16 staining, which is usually due to pRB pathway disruption [25,26]. p16 expression has also been observed in a wide range of other
SC
tumors such as liposarcomas and other soft tissue tumors, melanocytic tumors, adenocarcinomas
NU
and even lymphomas [27,33].
Limited evidence in the literature suggests that p16 could be overexpressed in a subset of
MA
follicular dendritic cell sarcomas as well. Griffin et al (2016) recently reported the presence of genetic alterations in the RB1 pathway in a significant portion of follicular dendritic cell
ED
sarcomas [21]. Bi-allelic loss of CDKN2A (which encodes p16) were seen in 2 of 13 cases and
PT
one-copy loss in 4 cases [21]. One case showed bi-allelic loss of RB1 and another a nonsense RB1 mutation [21]. Two additional cases harbored one-copy loss of RB1 [21]. Additional
CE
alterations in this pathway included copy number gains of CDK4 in four cases [21]. While one
AC
would anticipate p16 expression to be absent in tumors with loss of the p16 encoding gene CDKN2A, inactivation of RB1 could lead to p16 overexpression. Here, we characterized the pattern and extent of p16 expression in a series of 8 follicular dendritic cell sarcomas and found that p16 expression was indeed present in half of the cases (4 of 8). Furthermore, the pattern of expression would be considered positive by criteria established in the oropharynx for HPV surrogacy in 2 cases and equivocal in the remaining 2 cases [20,22]. pRB loss of expression was documented in 2 cases as the likely cause of p16 expression. It is possible that other alterations in the pRB pathway, such as CDK4 copy number gains observed
12
ACCEPTED MANUSCRIPT by Griffin et al (2015) in some follicular dendritic cell sarcomas, could lead to pRB inactivation (and therefore p16 overexpression) without loss of pRB expression in other cases [21].
T
Awareness of p16 expression in follicular dendritic cell sarcoma is important. Follicular
RI P
dendritic cell sarcoma has significant clinical and morphologic overlap with the much more commonly encountered HPV-related oropharyngeal SCC and is frequently misdiagnosed as SCC
SC
[8–11]. Follicular dendritic cell sarcoma is rare and so the diagnosis just may not be entertained
NU
in many cases. Due to wide availability and ease of interpretation, p16 immunohistochemistry is now not only recommended by the AJCC as a mandatory test for all oropharyngeal SCCs (as a
MA
surrogate for HPV) but also for SCC metastases of unknown primary in the neck as positivity suggests the oropharynx as the most likely origin [20]. In many oropharyngeal SCCs and SCC
ED
neck metastases, p16 immunohistochemistry may be the sole immunostain performed. However,
PT
the oropharynx and neck lymph nodes are also among the most common sources of follicular dendritic cell sarcomas and we have documented that a subset are also strongly and diffusely
CE
p16-positive. Thus, p16 positivity should only be used as a surrogate for HPV once the diagnosis
AC
of SCC has been definitively established. The use of p16 as a diagnostic marker of SCC should be avoided. Additional immunohistochemistry is critical when the histologic differential diagnosis includes other entities. In particular, diffuse cytokeratin expression is helpful to exclude follicular dendritic cell sarcoma as only rare and focal positivity has been documented [34,35]. Dendritic markers are also important as they are a hallmark of follicular dendritic cell sarcomas but we did not observe any dendritic marker expression in a pilot study of HPV-related oropharyngeal SCC. One could also consider EBV-related nasopharyngeal carcinoma in the differential diagnosis of follicular dendritic cell sarcoma, especially when the latter arises in the nasopharynx
13
ACCEPTED MANUSCRIPT as was the case in one of our study patients. EBV-related nasopharyngeal carcinomas are usually nonkeratinizing and share many histologic features with HPV-related oropharyngeal squamous
T
cell carcinomas. However, with the exception of the extremely rare inflammatory pseudotumor-
RI P
like variant, an EBV-driven, intraabdominal tumor, follicular dendritic cell sarcomas, including those in our study, are EBV-negative [7].
SC
In summary, follicular dendritic cell sarcomas can show marked overexpression of p16.
NU
In light of the rarity of such tumors, the difficulty in distinguishing them from HPV-related oropharyngeal SCC histologically, and their presentation in the oropharynx and/or cervical
MA
lymph nodes, pathologists must have a low threshold for immunohistochemistry for dendritic cell markers and cytokeratins in tumors at these head and neck sites when squamous
AC
CE
PT
ED
differentiation or keratin production is not present.
14
ACCEPTED MANUSCRIPT References: [1] Monda L, Warnke R, Rosai J. A primary lymph node malignancy with features suggestive
T
of dendritic reticulum cell differentiation. A report of 4 cases. Am J Pathol 1986;122:562–
RI P
72.
[2] Chan JK, Fletcher CD, Nayler SJ, Cooper K. Follicular dendritic cell sarcoma.
NU
currently recognized. Cancer 1997;79:294–313.
SC
Clinicopathologic analysis of 17 cases suggesting a malignant potential higher than
[3] Saygin C, Uzunaslan D, Ozguroglu M, Senocak M, Tuzuner N. Dendritic cell sarcoma: A
MA
pooled analysis including 462 cases with presentation of our case series. Crit Rev Oncol Hematol 2013;88:253–71. doi:10.1016/j.critrevonc.2013.05.006.
ED
[4] Pang J, Mydlarz WK, Gooi Z, Waters KM, Bishop J, Sciubba JJ, et al. Follicular dendritic
PT
cell sarcoma of the head and neck: Case report, literature review, and pooled analysis of 97 cases. Head Neck 2016;38:E2241–9. doi:10.1002/hed.24115.
CE
[5] Lu Z-J, Li J, Zhou S-H, Dai L-B, Yan S-X, Wu T-T, et al. Follicular dendritic cell sarcoma
AC
of the right tonsil: A case report and literature review. Oncol Lett 2015;9:575–82. doi:10.3892/ol.2014.2726. [6] Biddle DA, Ro JY, Yoon GS, Yong Y-WH, Ayala AG, Ordonez NG, et al. Extranodal follicular dendritic cell sarcoma of the head and neck region: three new cases, with a review of the literature. Mod Pathol Off J U S Can Acad Pathol Inc 2002;15:50–8. doi:10.1038/modpathol.3880489. [7] Chan JKC, Pileri SA, Delsol G, Fletcher CDM, Weiss LM, Grogg KL. Follicular dendritic cell sarcoma. In: Swerdlow SH, Campo E, Harris NL, Jaffe ES, Pileri SA, Stein H, et al, editors.
15
ACCEPTED MANUSCRIPT WHO classification of tumours of haematopoietic and lymphoid tissues. 4th ed. Lyon: International Agency for Research on Cancer; 2008, p. 363-4.
T
[8] Wu A, Pullarkat S. Follicular Dendritic Cell Sarcoma. Arch Pathol Lab Med 2016;140:186–
RI P
90. doi:10.5858/arpa.2014-0374-RS.
[9] Hu T, Wang X, Yu C, Yan J, Zhang X, Li L, et al. Follicular dendritic cell sarcoma of the
SC
pharyngeal region. Oncol Lett 2013;5:1467–76. doi:10.3892/ol.2013.1224.
NU
[10] Al-Hussain T, Saleem M, Velagapudi SB, Dababo MA. Follicular dendritic cell sarcoma of parapharyngeal space: a case report and review of the literature. Head Neck Pathol
MA
2015;9:135–9. doi:10.1007/s12105-014-0537-5.
[11] Duan G, Wu F, Zhu J, Guo D, Zhang R, Shen L, et al. Extranodal follicular dendritic cell
ED
sarcoma of the pharyngeal region: a potential diagnostic pitfall, with literature review. Am J
PT
Clin Pathol 2010;133:49–58. doi:10.1309/AJCP7U8YISBUAVNW. [12] Chaturvedi AK, Engels EA, Pfeiffer RM, Hernandez BY, Xiao W, Kim E, et al. Human
CE
papillomavirus and rising oropharyngeal cancer incidence in the United States. J Clin Oncol
AC
Off J Am Soc Clin Oncol 2011;29:4294–301. doi:10.1200/JCO.2011.36.4596. [13] Weiss D, Koopmann M, Rudack C. Prevalence and impact on clinicopathological characteristics of human papillomavirus-16 DNA in cervical lymph node metastases of head and neck squamous cell carcinoma. Head Neck 2011;33:856–62. doi:10.1002/hed.21548. [14] Compton AM, Moore-Medlin T, Herman-Ferdinandez L, Clark C, Caldito GC, Wang XI, et al. Human papillomavirus in metastatic lymph nodes from unknown primary head and neck squamous cell carcinoma. Otolaryngol--Head Neck Surg Off J Am Acad Otolaryngol-Head Neck Surg 2011;145:51–7. doi:10.1177/0194599811400385.
16
ACCEPTED MANUSCRIPT [15] Chernock RD, Lewis JS. Approach to metastatic carcinoma of unknown primary in the head and neck: squamous cell carcinoma and beyond. Head Neck Pathol 2015;9:6–15.
T
doi:10.1007/s12105-015-0616-2.
RI P
[16] Satoh K, Hibi G, Yamamoto Y, Urano M, Kuroda M, Nakamura S. Follicular dendritic cell tumor in the oro-pharyngeal region: report of a case and a review of the literature. Oral
SC
Oncol 2003;39:415–9.
NU
[17] Chernock RD, El-Mofty SK, Thorstad WL, Parvin CA, Lewis JS. HPV-Related Nonkeratinizing Squamous Cell Carcinoma of the Oropharynx: Utility of Microscopic
doi:10.1007/s12105-009-0126-1.
MA
Features in Predicting Patient Outcome. Head Neck Pathol 2009;3:186–94.
ED
[18] Chernock RD. Morphologic features of conventional squamous cell carcinoma of the
PT
oropharynx: “keratinizing” and “nonkeratinizing” histologic types as the basis for a consistent classification system. Head Neck Pathol 2012;6 Suppl 1:S41–7.
CE
doi:10.1007/s12105-012-0373-4.
AC
[19] Gondim DD, Haynes W, Wang X, Chernock RD, El-Mofty SK, Lewis JS. Histologic Typing in Oropharyngeal Squamous Cell Carcinoma: A 4-Year Prospective Practice Study With p16 and High-Risk HPV mRNA Testing Correlation. Am J Surg Pathol 2016;40:1117-24. doi:10.1097/PAS.0000000000000650. [20] Amin MB, Edge SB, Greene FL, Byrd DR, Brookland RK, Washington MK, et al. AJCC cancer staging manual. 8th ed. New York: Springer Science+Business Media; 2016. [21] Griffin GK, Sholl LM, Lindeman NI, Fletcher CD, Hornick JL. Targeted genomic sequencing of follicular dendritic cell sarcoma reveals recurrent alterations in NF-κB regulatory genes. Mod Pathol 2016;29:67-74. doi:10.1038/modpathol.2015.130.
17
ACCEPTED MANUSCRIPT [22] Lewis JS, Chernock RD, Ma X-J, Flanagan JJ, Luo Y, Gao G, et al. Partial p16 staining in oropharyngeal squamous cell carcinoma: extent and pattern correlate with human
doi:10.1038/modpathol.2012.79.
RI P
T
papillomavirus RNA status. Mod Pathol Off J U S Can Acad Pathol Inc 2012;25:1212–20.
[23] Kim WY, Sharpless NE. The regulation of INK4/ARF in cancer and aging. Cell
SC
2006;127:265–75. doi:10.1016/j.cell.2006.10.003.
NU
[24] Romagosa C, Simonetti S, López-Vicente L, Mazo A, Lleonart ME, Castellvi J, et al. p16(Ink4a) overexpression in cancer: a tumor suppressor gene associated with senescence
MA
and high-grade tumors. Oncogene 2011;30:2087–97. doi:10.1038/onc.2010.614. [25] Beasley MB, Lantuejoul S, Abbondanzo S, Chu W-S, Hasleton PS, Travis WD, et al. The
ED
P16/cyclin D1/Rb pathway in neuroendocrine tumors of the lung. Hum Pathol
PT
2003;34:136–42. doi:10.1053/hupa.2003.8. [26] Alos L, Hakim S, Larque A-B, de la Oliva J, Rodriguez-Carunchio L, Caballero M, et al.
CE
p16 overexpression in high-grade neuroendocrine carcinomas of the head and neck:
AC
potential diagnostic pitfall with HPV-related carcinomas. Virchows Arch Int J Pathol 2016;469:277–84. doi:10.1007/s00428-016-1982-1. [27] Mahajan A. Practical issues in the application of p16 immunohistochemistry in diagnostic pathology. Hum Pathol 2016;51:64–74. doi:10.1016/j.humpath.2015.12.021. [28] Gao G, Chernock RD, Gay HA, Thorstad WL, Zhang TR, Wang H, et al. A novel RT-PCR method for quantification of human papillomavirus transcripts in archived tissues and its application in oropharyngeal cancer prognosis. Int J Cancer J Int Cancer 2013;132:882–90. doi:10.1002/ijc.27739.
18
ACCEPTED MANUSCRIPT [29] Rooper LM, Gandhi M, Bishop JA, Westra WH. RNA in-situ hybridization is a practical and effective method for determining HPV status of oropharyngeal squamous cell
T
carcinoma including discordant cases that are p16 positive by immunohistochemistry but
RI P
HPV negative by DNA in-situ hybridization. Oral Oncol 2016;55:11–6. doi:10.1016/j.oraloncology.2016.02.008.
SC
[30] Ang KK, Harris J, Wheeler R, Weber R, Rosenthal DI, Nguyen-Tân PF, et al. Human
NU
papillomavirus and survival of patients with oropharyngeal cancer. N Engl J Med 2010;363:24–35. doi:10.1056/NEJMoa0912217.
MA
[31] Beadle BM, William WN, McLemore MS, Sturgis EM, Williams MD. p16 expression in cutaneous squamous carcinomas with neck metastases: a potential pitfall in identifying
PT
doi:10.1002/hed.23188.
ED
unknown primaries of the head and neck. Head Neck 2013;35:1527–33.
[32] Doxtader EE, Katzenstein A-LA. The relationship between p16 expression and high-risk
CE
human papillomavirus infection in squamous cell carcinomas from sites other than uterine
AC
cervix: a study of 137 cases. Hum Pathol 2012;43:327–32. doi:10.1016/j.humpath.2011.05.010. [33] Chang SY, Keeney M, Law M, Donovan J, Aubry M-C, Garcia J. Detection of human papillomavirus in non-small cell carcinoma of the lung. Hum Pathol 2015;46:1592–7. doi:10.1016/j.humpath.2015.07.012. [34] Jabbour MN, Fedda FA, Tawil AN, Shabb NS, Boulos FI. Follicular dendritic cell sarcoma of the head and neck expressing thyroid transcription factor-1: a case report with clinicopathologic and immunohistochemical literature review. Appl Immunohistochem Mol Morphol AIMM 2014;22:705–12. doi:10.1097/PAI.0b013e318224a5ce.
19
ACCEPTED MANUSCRIPT [35] Vaideeswar P, George SM, Kane SV, Chaturvedi RA, Pandit SP. Extranodal follicular dendritic cell sarcoma of the tonsil - case report of an epithelioid cell variant with
AC
CE
PT
ED
MA
NU
SC
RI P
T
osteoclastic giant cells. Pathol Res Pract 2009;205:149–53. doi:10.1016/j.prp.2008.07.006.
20
ACCEPTED MANUSCRIPT Figure legends: Fig. 1 Hematoxylin and eosin stained sections demonstrating the histologic features of follicular
T
dendritic cell sarcoma (A) and (C) and HPV-related squamous cell carcinoma of the oropharynx
RI P
(B) and (D). Both tumor types are composed of cells with oval to spindled nuclei, indistinct nucleoli, indistinct cell borders and tumor infiltrating lymphocytes. Follicular dendritic cell
SC
sarcoma often has a more fascicular/storiform growth pattern than HPV-related squamous cell
NU
carcinoma and usually a lower mitotic rate. Occasional intranuclear pseudoinclusions may be present in follicular dendritic cell sarcomas (C, arrow). (Original magnifications x400 [A,B,D]
MA
and x600 [C]).
ED
Fig. 2 p16 (A) and (C) and pRB (B) and (D) expression in follicular dendritic cell sarcoma. Case
PT
4 shows strong and diffuse, nuclear and cytoplasmic p16 expression (A) with corresponding loss of pRB expression in 100% of the tumor cells (B). Infiltrating lymphocytes show retained pRB
CE
expression. Case 2 shows moderate to strong p16 expression in 60% of the tumor cells (C) with
AC
pRB loss mostly restricted to regions of p16 expression (D, right) and retention of pRB expression in p16 negative areas of the tumor (D, left). (Original magnifications x200 [A,C,D] and x400 [B]).
21
AC
Figure 1
CE
PT
ED
MA
NU SC RI PT
ACCEPTED MANUSCRIPT
22
AC
Figure 2
CE
PT
ED
MA
NU SC RI PT
ACCEPTED MANUSCRIPT
23
ACCEPTED MANUSCRIPT
F
Right tonsil
-
-
2
29
M
Parapharyngeal space
60%
ModerateStrong
3
62
M
Lung
-
-
4
47
F
Rectum
100%
5
55
F
Abdomen
80%
6
42
M
Cervical lymph node
7
35
F
8
43
F
Retained Neck LNs
CR
35
Partial loss (70%)
ED
MA NU S
1
IP
T
Table 1. Clinicopathologic features and immunohistochemistry results in follicular dendritic cell sarcoma Case Age Sex Location p16 IHC pRB Met Treatment (years) IHC Extent Intensity
PT
Strong
None Local resection and lymph node dissection
Retained None
Loss (100%)
Radical resection subsequent lymph node dissection + radiation
Liver
Patient Status (Follow-up) NEOD (16 y)
NEOD (3 m)
Lobectomy (mid + lower) with regional lymph node dissection
NEOD (4 y)
Resection + radiation + adjuvant chemotherapy
AWD (3 y)
Retained None
Resection + adjuvant chemotherapy
NEOD (3 y)
-
-
Retained Lung
Resection + adjuvant chemotherapy
AWD (3 y)
Nasopharynx
80%
Moderate
Retroperitoneum
-
-
AC
CE
WeakStrong
Retained None Local resection and lymph node dissection
NEOD (4 m)
Retained None
NEOD (5 m)
Radical resection + adjuvant chemotherapy
Abbreviations: IHC=immunohistochemistry; F=female; M=male; met=metastasis; LNs=lymph nodes; y=years; NEOD=no evidence of disease; m=months; AWD=alive with disease
24
ACCEPTED MANUSCRIPT Highlights: Follicular dendritic cell sarcomas are rare and frequently misdiagnosed A subset of follicular dendritic cell sarcomas overexpress p16
p16 expression may cause diagnostic confusion with HPV-related oropharyngeal cancer
Dendritic markers and cytokeratins are critical in separating the two entities
AC
CE
PT
ED
MA
NU
SC
RI P
T
25
S0046-8177(17)30177-6 doi: 10.1016/j.humpath.2017.05.019 YHUPA 4239
To appear in:
Human Pathology
Received date: Revised date: Accepted date:
29 March 2017 12 May 2017 17 May 2017
Please cite this article as: Zhang Lingxin, Yang Chen, Lewis Jr James S., El-Mofty Samir K., Chernock Rebecca D., p16 expression in follicular dendritic cell sarcoma: A potential mimicker of HPV-related oropharyngeal squamous cell carcinoma, Human Pathology (2017), doi: 10.1016/j.humpath.2017.05.019
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT
T
p16 expression in follicular dendritic cell sarcoma: a potential mimicker of HPV-related oropharyngeal squamous cell carcinoma Lingxin Zhang, MD; aChen Yang, MD; b,cJames S. Lewis Jr, MD; a,dSamir K. El-Mofty, DMD, PhD, MS; a,dRebecca D. Chernock, MD
RI P
a
a
Rebecca D. Chernock, MD Washington University School of Medicine Campus Box 8118 660 S. Euclid Ave St. Louis, MO 63110 Phone: 314-362-0101 Email: [email protected]
AC
CE
PT
Correspondence:
ED
MA
NU
SC
Department of Pathology and Immunology, Washington University School of Medicine, 660 S Euclid Ave, St. Louis, MO, USA, 63110 b Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, 1211 Medical Center Dr, Nashville, TN, USA, 37232 c Department of Otolaryngology, Vanderbilt University Medical Center, Nashville, TN, USA, 37232 d Department of Otolaryngology Head and Neck Surgery, Washington University School of Medicine, 660 S Euclid Ave, St. Louis, MO, USA, 63110
Running tittle: p16 in follicular dendritic cell sarcoma
Conflicts of interest and funding disclosures: The authors have no conflicts of interest or sources of support to disclose. This research did not receive any specific grant from funding agencies in the public, commercial or not-for-profit sector.
1
ACCEPTED MANUSCRIPT Summary Follicular dendritic cell sarcoma is a rare mesenchymal neoplasm that most commonly occurs in cervical lymph nodes. It has histologic and clinical overlap with the much
T
more common p16-positive human papillomavirus (HPV)-related squamous cell carcinoma of
RI P
the oropharynx which characteristically has nonkeratinizing morphology and often presents as an isolated neck mass. Not surprisingly, follicular dendritic cell sarcomas are commonly
SC
misdiagnosed as squamous cell carcinoma. Immunohistochemistry is helpful in separating the
NU
two entities. Follicular dendritic cell sarcoma expresses dendritic markers such as CD21 and CD23 and is almost always cytokeratin negative. However, in many cases of HPV-related
MA
oropharyngeal carcinoma, only p16 immunohistochemistry as a prognostic and surrogate marker for HPV is performed. p16 expression in follicular dendritic cell sarcoma has not been
ED
characterized. Here, we investigate the expression of p16 in follicular dendritic cell sarcoma and
PT
correlate it with retinoblastoma protein expression. A pilot study of dendritic marker expression in HPV-related oropharyngeal squamous cell carcinoma was also performed. We found that 4 of
CE
8 sarcomas expressed p16 with strong and diffuse staining in 2 cases. In 2 of the 4 cases, p16
AC
expression corresponded to loss of retinoblastoma protein expression. Dendritic marker expression (CD21 and CD23) was not found in HPV-related oropharyngeal squamous cell carcinomas. As such, positive p16 immunohistochemistry cannot be used as supportive evidence for the diagnosis of squamous cell carcinoma as strong and diffuse p16 expression may also occur in follicular dendritic cell sarcoma. Cytokeratins and dendritic markers are critical in separating the two tumor types.
Keywords: p16 immunohistochemistry; human papillomavirus; follicular dendritic cell sarcoma; nonkeratinizing; squamous cell carcinoma; oropharyngeal
2
ACCEPTED MANUSCRIPT 1. Introduction Follicular dendritic cell sarcoma is a rare, low-grade mesenchymal neoplasm initially
T
described by Monda and colleagues in 1986 [1]. The tumor is thought to originate from the
RI P
follicular dendritic cell which is a part of the innate immune system, primarily playing a role in antigen presentation, and located mainly in the germinal centers of lymphoid follicles [2]. As
SC
such, lymph node involvement, especially cervical, is most common [3]. Follicular dendritic cell
NU
sarcomas may also occur at a wide variety of extranodal sites including the oropharynx, neck soft tissue, parapharyngeal space, thyroid, liver, kidney and axial skeleton, among others [3–6]. A
MA
very rare inflammatory pseudotumor-like variant that occurs predominantly in the liver and spleen is Epstein-Barr virus (EBV) driven but conventional follicular dendritic cell sarcomas are
ED
not [7]. Middle-aged adults of both genders are mainly affected and surgery is the mainstay of
free survival of 34% [4].
PT
therapy. A pooled analysis of 97 patients showed a 5-year overall survival of 81% and disease-
CE
The histologic diagnosis of follicular dendritic cell sarcoma is challenging for several
diagnosis.
AC
reasons. First, it is a rare tumor type and thus may not be considered initially in the differential Further, there are several morphologic mimics including squamous cell or
undifferentiated carcinoma, meningioma and even paraganglioma, all of which are more common, and therefore may be given more consideration at the time of diagnosis. In fact, greater than 50% of follicular dendritic cell sarcomas are initially misdiagnosed as other entities, the majority as either carcinoma or meningioma [8–11]. Misdiagnosis as human papillomavirus (HPV)-related oropharyngeal squamous cell carcinoma (SCC) is of particular concern, given the significant clinical as well as histologic overlap with follicular dendritic cell sarcoma. HPV-related oropharyngeal SCCs are much more
3
ACCEPTED MANUSCRIPT common and have been increasing in incidence over the past several decades [12]. Just as follicular dendritic cell sarcomas most commonly arise in cervical lymph nodes of middle-aged
T
adults, approximately one-third of HPV-related oropharyngeal SCCs also present as an isolated
oropharynx [13-15].
RI P
neck mass, typically in middle-aged to older adults, without an obvious primary tumor in the In addition, follicular dendritic cell sarcomas may also occur in the
SC
oropharynx, especially the tonsils, where most HPV-related SCCs originate [5,16].
19].
NU
HPV-related oropharyngeal SCCs are typically, but not exclusively, nonkeratinizing [17Nonkeratinizing SCCs share many morphologic features with follicular dendritic cell
MA
sarcomas. Like follicular dendritic cell sarcoma, nonkeratinizing SCC is composed of oval to spindled cells with indistinct cell borders and indistinct nucleoli [17,18]. Infiltrating lymphocytes
ED
are usually present in both as well. Distinguishing histologic features include the presence of
PT
focal squamous maturation or keratin production and nested to ribbon-like growth in nonkeratinizing SCC versus fascicular to storiform growth and intranuclear pseudoinclusions in
CE
follicular dendritic cell sarcoma [7,17,18]. Mitotic activity is usually higher in SCC. However,
AC
these differentiating features may not be well represented on biopsy material or may not be obvious to a pathologist who is not familiar with both entities. Immunohistochemistry is useful in separating the two since follicular dendritic cell sarcomas are almost always cytokeratin (but not epithelial membrane antigen) negative and nonkeratinizing SCCs are cytokeratin positive [7]. Additionally, follicular dendritic cell sarcomas express dendritic markers (CD21, CD23 and CD35) and, while dendritic marker expression has not been investigated in nonkeratinizing SCC, it is unlikely to be present. However, in many cases of oropharyngeal SCC (and their metastases presenting as an unknown primary in the neck), p16 immunohistochemistry as a prognostic marker and surrogate for HPV
4
ACCEPTED MANUSCRIPT may be the sole immunostain performed. In fact, p16 is now recommended by the American Joint Committee on Cancer (AJCC) as the preferred method of HPV testing in oropharyngeal
T
SCCs and metastases of unknown primary in the neck [20]. p16 expression in follicular dendritic
RI P
cell sarcoma has not be fully elucidated but there is some indication that it may be present in a subset. Recently, Griffin et al (2016) found Retinoblastoma (RB1) inactivation (which could
SC
theoretically lead to p16 overexpression) in several follicular dendritic cell sarcomas [21].
NU
Here, we characterize the extent and pattern of p16 expression by immunohistochemistry in a series of follicular dendritic cell sarcomas, as p16 expression in follicular dendritic cell
MA
sarcoma could be a potential pitfall leading to an erroneous diagnosis of HPV-related nonkeratinizing oropharyngeal SCC. In addition, we perform a pilot study of CD21 and CD23
ED
expression in HPV-related nonkeratinizing oropharyngeal SCC to exclude the possibility of
AC
CE
2. Materials and Methods
PT
aberrant dendritic marker positivity in this tumor type.
2.1. Patients and samples
Human subject materials were utilized according to the guidelines set by the Human Studies Protection Office at Washington University in St. Louis and at Vanderbilt University with a waiver of consent. All follicular dendritic cell sarcomas with material available for review were retrospectively retrieved from the Pathology Department files for p16 and retinoblastoma protein (pRB) immunohistochemistry and EBV-encoded small RNA (EBER) in situ hybridization (ISH) for EBV. Cases were reviewed by 3 study authors (LZ, CY, RDC) to
5
ACCEPTED MANUSCRIPT confirm the diagnoses. Diagnostic inclusion criteria included: typical morphology (oval to spindled cells often forming fascicles with indistinct cell borders and infiltrating lymphocytes) as
T
described in the current World Health Organization Classification of Tumours of Haematopoietic
RI P
and Lymphoid Tissue, positivity for at least one dendritic marker, and absence of cytokeratin expression [7]. Immunohistochemistry, including dendritic markers and cytokeratins, was
NU
were extracted from the electronic medical records.
SC
performed as part of the routine diagnostic work-up in all cases. Demographic and clinical data
Ten representative nonkeratinizing SCCs of the oropharynx from surgically resected
MA
specimens were selected from the Washington University Pathology Department files for dendritic marker immunohistochemistry (CD21 and CD23), all of which were known to be p16-
ED
positive by immunohistochemistry (≥ 75% nuclear and cytoplasmic staining of at least moderate
PT
intensity) performed routinely in clinical practice as a prognostic marker and surrogate for HPV. Exclusion criteria included: tumors measuring < 1 cm (to avoid tissue depletion) and prior
CE
intraoperative frozen section analysis or obscuring thermal/cautery artifact, which may interfere
AC
with tumor immunogenicity.
2.2. Immunohistochemistry
Immunohistochemistry utilized formalin-fixed paraffin-embedded tissue cut at 4 µm sections and floated onto charged slides. Immunohistochemistry for p16 (E6H4 clone, CINtec; Ventana Medical Systems, Inc., Tucson, AZ), CD21 (2G9 clone; Cell Marque, Rocklin, CA) and CD23 (SP23 clone; Ventana Medical Systems, Inc., Tucson, AZ) was performed on a Ventana Benchmark automated immunostainer (Ventana Medical Systems, Inc., Tucson, AZ) by standard
6
ACCEPTED MANUSCRIPT protocols with adequate controls. Antigen retrieval, standard on the machine, utilized the Ventana Ultra CC1, EDTA-Tris pH 8.0 solution. Immunohistochemistry for pRB was performed
T
by NeoGenomics (G3-245 clone; BD Bioscience, San Diego, CA) on a Bond-III Autostainer
RI P
(Leica Biosystems Inc., Buffalo Grove, IL) by standard protocols with adequate controls. Antigen retrieval utilized Leica Bond Epitope Retrieval solution 2 (EDTA based buffer, pH 9.0).
SC
p16 immunohistochemistry was characterized by percent of nuclear and cytoplasmic
NU
staining as well as the intensity (weak, moderate or strong). p16 immunohistochemistry was also recorded as positive or negative according to established criteria for oropharyngeal SCC: ≥ 75%
MA
nuclear expression of at least moderate intensity [20]. pRB immunohistochemistry was interpreted as percent loss of nuclear staining in tumor cells with adequate positive internal
ED
control staining of non-neoplastic tissues. For the dendritic markers CD21 and CD23, percent of
PT
cells with cytoplasmic staining and intensity (weak, moderate or strong) was recorded.
AC
RDC).
CE
Interpretation of the immunohistochemical stains was performed by three study authors (LZ, CY,
2.3. In situ hybridization
ISH for EBER was performed on formalin-fixed, paraffin-embedded 4-μm tissue sections using a I View Blue Plus Detection Kit (Ventana Medical System). The assays used the Ventana INFORM EBER probe. Staining was in a totally enclosed system and was performed according to the manufacturer's instructions with adequate controls. Ventana Red Counterstain II (Ventana Medical System) was used. Positive staining was identified as blue nuclear dots. Any definitive
7
ACCEPTED MANUSCRIPT nuclear staining in the tumor cells was considered positive. Cases were classified in a binary
T
manner as either positive or negative by three study authors (LZ, CY, RDC).
RI P
3. Results
NU
SC
3.1. Clinical and pathologic features of follicular dendritic cell sarcoma cases
Eight cases of follicular dendritic cell sarcoma were identified from the Pathology
MA
Department files, 6 from Washington University in St. Louis and 2 from Vanderbilt University (Table 1). The mean age of the patients was 43.5 years (range 29 to 62 years) with a male to
ED
female ratio of 3:5. Four tumors (50%) were from the head and neck region: 1 arose in a cervical
PT
lymph node, 1 in the tonsil, 1 in the parapharyngeal space and 1 in the nasopharynx. The tumors had morphologic features typical of follicular dendritic cell sarcoma including oval to spindled
CE
nuclei with small to indistinct nucleoli, indistinct cell borders, and infiltrating lymphocytes. All
AC
cases were positive for the dendritic marker CD21 and negative for at least one cytokeratin. Additional dendritic markers were performed in a subset as part of the initial diagnostic evaluation. Five of 6 cases tested were CD35 positive and 3 of 4 were CD23 positive. Representative histologic images are shown in Fig.1. All patients were treated with surgical resection. Four received adjuvant chemotherapy and 2 radiotherapy. Three patients developed metastases, 1 of whom underwent successful resection of the metastasis and was free of disease at last follow-up 16 years after initial diagnosis. The other 2 patients with metastases are alive with disease at last follow-up. The
8
ACCEPTED MANUSCRIPT remaining 6 patients were disease-free at last follow-up. The median follow-up time was 3.5
T
years (range 3 months to 16 years).
RI P
3.2. p16 and pRB expression in follicular dendritic cell sarcomas
SC
Immunohistochemistry results are detailed in Table 1. Four (50%) of the follicular
NU
dendritic cell sarcomas showed p16 expression. Applying the criteria for p16 positivity established in oropharyngeal SCC (≥ 75% nuclear expression of at least moderate intensity), 2
MA
cases were p16 positive with strong staining in 100% of cells in one case and moderate staining in 80% of cells in the other[20]. Although nuclear staining was considered sufficient for
ED
positivity, all cases had both nuclear and cytoplasmic staining. One case that had p16 expression
PT
did not meet the oropharyngeal SCC criteria for positivity because the extent of staining was 60% (≤ 75%) and the other case because there was variable intensity of the staining (weak to
CE
strong) even though 80% of cells were positive. The staining patterns in both of these cases
AC
would be considered equivocal, if observed in oropharyngeal SCC as surrogacy for HPV [22]. Of the 4 cases with p16 expression, 2 showed loss of pRB expression by immunohistochemistry. Areas of pRB loss were nearly entirely restricted to areas of p16 expression. Representative images of p16 expression and pRB loss are shown in Fig. 2.
3.3. EBV in follicular dendritic cell sarcoma
9
ACCEPTED MANUSCRIPT None of the tumors had a dense inflammatory infiltrate characteristic of the inflammatory pseudotumor-like variant of follicular dendritic cell sarcoma, which is an EBV-driven tumor.
RI P
T
Furthermore, all tumors were negative for EBV by EBER ISH.
3.4. CD21 and CD23 dendritic marker expression in p16-positive (HPV-related)
NU
SC
nonkeratinizing oropharyngeal SCCs
A pilot study of dendritic marker expression in p16-positive (HPV-related)
MA
nonkeratinizing oropharyngeal SCC was undertaken. Dendritic markers CD21 and CD23 were negative in all 10 cases. Thus, aberrant dendritic marker expression was not observed in
ED
nonkeratinizing oropharyngeal SCC. Representative images of the nonkeratinizing SCCs are
CE
4. Discussion
PT
shown in Fig. 1 and demonstrate the morphologic overlap with follicular dendritic cell sarcoma.
AC
p16 is a tumor suppressor protein encoded by the CDKN2A gene located on chromosome 9p21. When bound with cyclin dependent kinase (CDK) 4 and 6, p16 blocks their interaction with cyclin D1, which in turn keeps pRB in a hypophosphorylated state and prevents cell-cycle progression through E2F1 transcription factor repression [23]. Although both function in concert as tumor suppressors by maintaining cellular senescence, pRB also paradoxically negatively regulates p16 [24]. Thus, loss of pRB expression often leads to p16 overexpression. While a wide variety of human tumors harbor genetic alterations that lead to p16 inactivation (gene mutation, deletion or hypermethylation), a smaller but growing number of tumors overexpress p16, which is often, but not always, a consequence of pRB mutation or loss
10
ACCEPTED MANUSCRIPT of function releasing p16 from pRB-mediated inhibition [24–27]. One such unique example of the latter is in HPV-driven SCCs.
HPV oncoproteins E6 and E7 induce malignant
T
transformation by binding to and inactivating tumor suppressor proteins p53 and pRB,
RI P
respectively [24]. Virus-mediated loss of pRB function leads to high levels of p16 expression in HPV-related SCCs of the head and neck and anogenital region [24]. Detection of p16
SC
overexpression by immunohistochemistry has emerged as a robust surrogate marker of HPV-
[28,29].
NU
related SCC in the oropharynx that is both sensitive (>95%) and specific (>90%) in this setting In fact, p16 immunohistochemistry has been endorsed by the AJCC as the
MA
recommended HPV-testing method that should be performed in all oropharyngeal SCCs [20]. Importantly, the p16 staining pattern must be moderate to strong, diffuse (≥ 75% of cells) and
ED
including nuclear positivity, although staining is almost always both nuclear and cytoplasmic
PT
[20]. Determining tumor HPV status in oropharyngeal SCCs is critical because HPV-related oropharyngeal SCCs have a significantly better prognosis compared to HPV-negative tumors
CE
[30]. As a result, patients are often stratified by tumor HPV status when determining clinical trial
AC
eligibility and may receive different treatment outside the context of a trial in the near future. The difference in clinical behavior is now also reflected in the separate staging systems for p16positive (HPV-related) versus p16-negative (HPV-unrelated) oropharyngeal SCC in the new 8th edition of the AJCC Cancer Staging Manual [20]. The high specificity of p16 for HPV-related SCC in the oropharynx is in part due to the high prevalence of HPV-related tumors, accounting for well over half of SCCs in the United States, at this site [12]. The specificity of p16 for HPV-related SCC declines outside of the oropharynx where the prevalence of HPV-related SCC is much lower. This is because there is a growing list of other tumors that demonstrate strong and diffuse p16 expression through HPV-
11
ACCEPTED MANUSCRIPT independent mechanisms [25–27,31,32]. HPV-negative SCCs of various sites occasionally show extensive p16 overexpression with some of the highest rates so far (20% or more) documented in
T
cutaneous head and neck SCCs [31,32]. Neuroendocrine tumors, especially high grade ones such
RI P
as small cell carcinoma, frequently show strong and diffuse p16 staining, which is usually due to pRB pathway disruption [25,26]. p16 expression has also been observed in a wide range of other
SC
tumors such as liposarcomas and other soft tissue tumors, melanocytic tumors, adenocarcinomas
NU
and even lymphomas [27,33].
Limited evidence in the literature suggests that p16 could be overexpressed in a subset of
MA
follicular dendritic cell sarcomas as well. Griffin et al (2016) recently reported the presence of genetic alterations in the RB1 pathway in a significant portion of follicular dendritic cell
ED
sarcomas [21]. Bi-allelic loss of CDKN2A (which encodes p16) were seen in 2 of 13 cases and
PT
one-copy loss in 4 cases [21]. One case showed bi-allelic loss of RB1 and another a nonsense RB1 mutation [21]. Two additional cases harbored one-copy loss of RB1 [21]. Additional
CE
alterations in this pathway included copy number gains of CDK4 in four cases [21]. While one
AC
would anticipate p16 expression to be absent in tumors with loss of the p16 encoding gene CDKN2A, inactivation of RB1 could lead to p16 overexpression. Here, we characterized the pattern and extent of p16 expression in a series of 8 follicular dendritic cell sarcomas and found that p16 expression was indeed present in half of the cases (4 of 8). Furthermore, the pattern of expression would be considered positive by criteria established in the oropharynx for HPV surrogacy in 2 cases and equivocal in the remaining 2 cases [20,22]. pRB loss of expression was documented in 2 cases as the likely cause of p16 expression. It is possible that other alterations in the pRB pathway, such as CDK4 copy number gains observed
12
ACCEPTED MANUSCRIPT by Griffin et al (2015) in some follicular dendritic cell sarcomas, could lead to pRB inactivation (and therefore p16 overexpression) without loss of pRB expression in other cases [21].
T
Awareness of p16 expression in follicular dendritic cell sarcoma is important. Follicular
RI P
dendritic cell sarcoma has significant clinical and morphologic overlap with the much more commonly encountered HPV-related oropharyngeal SCC and is frequently misdiagnosed as SCC
SC
[8–11]. Follicular dendritic cell sarcoma is rare and so the diagnosis just may not be entertained
NU
in many cases. Due to wide availability and ease of interpretation, p16 immunohistochemistry is now not only recommended by the AJCC as a mandatory test for all oropharyngeal SCCs (as a
MA
surrogate for HPV) but also for SCC metastases of unknown primary in the neck as positivity suggests the oropharynx as the most likely origin [20]. In many oropharyngeal SCCs and SCC
ED
neck metastases, p16 immunohistochemistry may be the sole immunostain performed. However,
PT
the oropharynx and neck lymph nodes are also among the most common sources of follicular dendritic cell sarcomas and we have documented that a subset are also strongly and diffusely
CE
p16-positive. Thus, p16 positivity should only be used as a surrogate for HPV once the diagnosis
AC
of SCC has been definitively established. The use of p16 as a diagnostic marker of SCC should be avoided. Additional immunohistochemistry is critical when the histologic differential diagnosis includes other entities. In particular, diffuse cytokeratin expression is helpful to exclude follicular dendritic cell sarcoma as only rare and focal positivity has been documented [34,35]. Dendritic markers are also important as they are a hallmark of follicular dendritic cell sarcomas but we did not observe any dendritic marker expression in a pilot study of HPV-related oropharyngeal SCC. One could also consider EBV-related nasopharyngeal carcinoma in the differential diagnosis of follicular dendritic cell sarcoma, especially when the latter arises in the nasopharynx
13
ACCEPTED MANUSCRIPT as was the case in one of our study patients. EBV-related nasopharyngeal carcinomas are usually nonkeratinizing and share many histologic features with HPV-related oropharyngeal squamous
T
cell carcinomas. However, with the exception of the extremely rare inflammatory pseudotumor-
RI P
like variant, an EBV-driven, intraabdominal tumor, follicular dendritic cell sarcomas, including those in our study, are EBV-negative [7].
SC
In summary, follicular dendritic cell sarcomas can show marked overexpression of p16.
NU
In light of the rarity of such tumors, the difficulty in distinguishing them from HPV-related oropharyngeal SCC histologically, and their presentation in the oropharynx and/or cervical
MA
lymph nodes, pathologists must have a low threshold for immunohistochemistry for dendritic cell markers and cytokeratins in tumors at these head and neck sites when squamous
AC
CE
PT
ED
differentiation or keratin production is not present.
14
ACCEPTED MANUSCRIPT References: [1] Monda L, Warnke R, Rosai J. A primary lymph node malignancy with features suggestive
T
of dendritic reticulum cell differentiation. A report of 4 cases. Am J Pathol 1986;122:562–
RI P
72.
[2] Chan JK, Fletcher CD, Nayler SJ, Cooper K. Follicular dendritic cell sarcoma.
NU
currently recognized. Cancer 1997;79:294–313.
SC
Clinicopathologic analysis of 17 cases suggesting a malignant potential higher than
[3] Saygin C, Uzunaslan D, Ozguroglu M, Senocak M, Tuzuner N. Dendritic cell sarcoma: A
MA
pooled analysis including 462 cases with presentation of our case series. Crit Rev Oncol Hematol 2013;88:253–71. doi:10.1016/j.critrevonc.2013.05.006.
ED
[4] Pang J, Mydlarz WK, Gooi Z, Waters KM, Bishop J, Sciubba JJ, et al. Follicular dendritic
PT
cell sarcoma of the head and neck: Case report, literature review, and pooled analysis of 97 cases. Head Neck 2016;38:E2241–9. doi:10.1002/hed.24115.
CE
[5] Lu Z-J, Li J, Zhou S-H, Dai L-B, Yan S-X, Wu T-T, et al. Follicular dendritic cell sarcoma
AC
of the right tonsil: A case report and literature review. Oncol Lett 2015;9:575–82. doi:10.3892/ol.2014.2726. [6] Biddle DA, Ro JY, Yoon GS, Yong Y-WH, Ayala AG, Ordonez NG, et al. Extranodal follicular dendritic cell sarcoma of the head and neck region: three new cases, with a review of the literature. Mod Pathol Off J U S Can Acad Pathol Inc 2002;15:50–8. doi:10.1038/modpathol.3880489. [7] Chan JKC, Pileri SA, Delsol G, Fletcher CDM, Weiss LM, Grogg KL. Follicular dendritic cell sarcoma. In: Swerdlow SH, Campo E, Harris NL, Jaffe ES, Pileri SA, Stein H, et al, editors.
15
ACCEPTED MANUSCRIPT WHO classification of tumours of haematopoietic and lymphoid tissues. 4th ed. Lyon: International Agency for Research on Cancer; 2008, p. 363-4.
T
[8] Wu A, Pullarkat S. Follicular Dendritic Cell Sarcoma. Arch Pathol Lab Med 2016;140:186–
RI P
90. doi:10.5858/arpa.2014-0374-RS.
[9] Hu T, Wang X, Yu C, Yan J, Zhang X, Li L, et al. Follicular dendritic cell sarcoma of the
SC
pharyngeal region. Oncol Lett 2013;5:1467–76. doi:10.3892/ol.2013.1224.
NU
[10] Al-Hussain T, Saleem M, Velagapudi SB, Dababo MA. Follicular dendritic cell sarcoma of parapharyngeal space: a case report and review of the literature. Head Neck Pathol
MA
2015;9:135–9. doi:10.1007/s12105-014-0537-5.
[11] Duan G, Wu F, Zhu J, Guo D, Zhang R, Shen L, et al. Extranodal follicular dendritic cell
ED
sarcoma of the pharyngeal region: a potential diagnostic pitfall, with literature review. Am J
PT
Clin Pathol 2010;133:49–58. doi:10.1309/AJCP7U8YISBUAVNW. [12] Chaturvedi AK, Engels EA, Pfeiffer RM, Hernandez BY, Xiao W, Kim E, et al. Human
CE
papillomavirus and rising oropharyngeal cancer incidence in the United States. J Clin Oncol
AC
Off J Am Soc Clin Oncol 2011;29:4294–301. doi:10.1200/JCO.2011.36.4596. [13] Weiss D, Koopmann M, Rudack C. Prevalence and impact on clinicopathological characteristics of human papillomavirus-16 DNA in cervical lymph node metastases of head and neck squamous cell carcinoma. Head Neck 2011;33:856–62. doi:10.1002/hed.21548. [14] Compton AM, Moore-Medlin T, Herman-Ferdinandez L, Clark C, Caldito GC, Wang XI, et al. Human papillomavirus in metastatic lymph nodes from unknown primary head and neck squamous cell carcinoma. Otolaryngol--Head Neck Surg Off J Am Acad Otolaryngol-Head Neck Surg 2011;145:51–7. doi:10.1177/0194599811400385.
16
ACCEPTED MANUSCRIPT [15] Chernock RD, Lewis JS. Approach to metastatic carcinoma of unknown primary in the head and neck: squamous cell carcinoma and beyond. Head Neck Pathol 2015;9:6–15.
T
doi:10.1007/s12105-015-0616-2.
RI P
[16] Satoh K, Hibi G, Yamamoto Y, Urano M, Kuroda M, Nakamura S. Follicular dendritic cell tumor in the oro-pharyngeal region: report of a case and a review of the literature. Oral
SC
Oncol 2003;39:415–9.
NU
[17] Chernock RD, El-Mofty SK, Thorstad WL, Parvin CA, Lewis JS. HPV-Related Nonkeratinizing Squamous Cell Carcinoma of the Oropharynx: Utility of Microscopic
doi:10.1007/s12105-009-0126-1.
MA
Features in Predicting Patient Outcome. Head Neck Pathol 2009;3:186–94.
ED
[18] Chernock RD. Morphologic features of conventional squamous cell carcinoma of the
PT
oropharynx: “keratinizing” and “nonkeratinizing” histologic types as the basis for a consistent classification system. Head Neck Pathol 2012;6 Suppl 1:S41–7.
CE
doi:10.1007/s12105-012-0373-4.
AC
[19] Gondim DD, Haynes W, Wang X, Chernock RD, El-Mofty SK, Lewis JS. Histologic Typing in Oropharyngeal Squamous Cell Carcinoma: A 4-Year Prospective Practice Study With p16 and High-Risk HPV mRNA Testing Correlation. Am J Surg Pathol 2016;40:1117-24. doi:10.1097/PAS.0000000000000650. [20] Amin MB, Edge SB, Greene FL, Byrd DR, Brookland RK, Washington MK, et al. AJCC cancer staging manual. 8th ed. New York: Springer Science+Business Media; 2016. [21] Griffin GK, Sholl LM, Lindeman NI, Fletcher CD, Hornick JL. Targeted genomic sequencing of follicular dendritic cell sarcoma reveals recurrent alterations in NF-κB regulatory genes. Mod Pathol 2016;29:67-74. doi:10.1038/modpathol.2015.130.
17
ACCEPTED MANUSCRIPT [22] Lewis JS, Chernock RD, Ma X-J, Flanagan JJ, Luo Y, Gao G, et al. Partial p16 staining in oropharyngeal squamous cell carcinoma: extent and pattern correlate with human
doi:10.1038/modpathol.2012.79.
RI P
T
papillomavirus RNA status. Mod Pathol Off J U S Can Acad Pathol Inc 2012;25:1212–20.
[23] Kim WY, Sharpless NE. The regulation of INK4/ARF in cancer and aging. Cell
SC
2006;127:265–75. doi:10.1016/j.cell.2006.10.003.
NU
[24] Romagosa C, Simonetti S, López-Vicente L, Mazo A, Lleonart ME, Castellvi J, et al. p16(Ink4a) overexpression in cancer: a tumor suppressor gene associated with senescence
MA
and high-grade tumors. Oncogene 2011;30:2087–97. doi:10.1038/onc.2010.614. [25] Beasley MB, Lantuejoul S, Abbondanzo S, Chu W-S, Hasleton PS, Travis WD, et al. The
ED
P16/cyclin D1/Rb pathway in neuroendocrine tumors of the lung. Hum Pathol
PT
2003;34:136–42. doi:10.1053/hupa.2003.8. [26] Alos L, Hakim S, Larque A-B, de la Oliva J, Rodriguez-Carunchio L, Caballero M, et al.
CE
p16 overexpression in high-grade neuroendocrine carcinomas of the head and neck:
AC
potential diagnostic pitfall with HPV-related carcinomas. Virchows Arch Int J Pathol 2016;469:277–84. doi:10.1007/s00428-016-1982-1. [27] Mahajan A. Practical issues in the application of p16 immunohistochemistry in diagnostic pathology. Hum Pathol 2016;51:64–74. doi:10.1016/j.humpath.2015.12.021. [28] Gao G, Chernock RD, Gay HA, Thorstad WL, Zhang TR, Wang H, et al. A novel RT-PCR method for quantification of human papillomavirus transcripts in archived tissues and its application in oropharyngeal cancer prognosis. Int J Cancer J Int Cancer 2013;132:882–90. doi:10.1002/ijc.27739.
18
ACCEPTED MANUSCRIPT [29] Rooper LM, Gandhi M, Bishop JA, Westra WH. RNA in-situ hybridization is a practical and effective method for determining HPV status of oropharyngeal squamous cell
T
carcinoma including discordant cases that are p16 positive by immunohistochemistry but
RI P
HPV negative by DNA in-situ hybridization. Oral Oncol 2016;55:11–6. doi:10.1016/j.oraloncology.2016.02.008.
SC
[30] Ang KK, Harris J, Wheeler R, Weber R, Rosenthal DI, Nguyen-Tân PF, et al. Human
NU
papillomavirus and survival of patients with oropharyngeal cancer. N Engl J Med 2010;363:24–35. doi:10.1056/NEJMoa0912217.
MA
[31] Beadle BM, William WN, McLemore MS, Sturgis EM, Williams MD. p16 expression in cutaneous squamous carcinomas with neck metastases: a potential pitfall in identifying
PT
doi:10.1002/hed.23188.
ED
unknown primaries of the head and neck. Head Neck 2013;35:1527–33.
[32] Doxtader EE, Katzenstein A-LA. The relationship between p16 expression and high-risk
CE
human papillomavirus infection in squamous cell carcinomas from sites other than uterine
AC
cervix: a study of 137 cases. Hum Pathol 2012;43:327–32. doi:10.1016/j.humpath.2011.05.010. [33] Chang SY, Keeney M, Law M, Donovan J, Aubry M-C, Garcia J. Detection of human papillomavirus in non-small cell carcinoma of the lung. Hum Pathol 2015;46:1592–7. doi:10.1016/j.humpath.2015.07.012. [34] Jabbour MN, Fedda FA, Tawil AN, Shabb NS, Boulos FI. Follicular dendritic cell sarcoma of the head and neck expressing thyroid transcription factor-1: a case report with clinicopathologic and immunohistochemical literature review. Appl Immunohistochem Mol Morphol AIMM 2014;22:705–12. doi:10.1097/PAI.0b013e318224a5ce.
19
ACCEPTED MANUSCRIPT [35] Vaideeswar P, George SM, Kane SV, Chaturvedi RA, Pandit SP. Extranodal follicular dendritic cell sarcoma of the tonsil - case report of an epithelioid cell variant with
AC
CE
PT
ED
MA
NU
SC
RI P
T
osteoclastic giant cells. Pathol Res Pract 2009;205:149–53. doi:10.1016/j.prp.2008.07.006.
20
ACCEPTED MANUSCRIPT Figure legends: Fig. 1 Hematoxylin and eosin stained sections demonstrating the histologic features of follicular
T
dendritic cell sarcoma (A) and (C) and HPV-related squamous cell carcinoma of the oropharynx
RI P
(B) and (D). Both tumor types are composed of cells with oval to spindled nuclei, indistinct nucleoli, indistinct cell borders and tumor infiltrating lymphocytes. Follicular dendritic cell
SC
sarcoma often has a more fascicular/storiform growth pattern than HPV-related squamous cell
NU
carcinoma and usually a lower mitotic rate. Occasional intranuclear pseudoinclusions may be present in follicular dendritic cell sarcomas (C, arrow). (Original magnifications x400 [A,B,D]
MA
and x600 [C]).
ED
Fig. 2 p16 (A) and (C) and pRB (B) and (D) expression in follicular dendritic cell sarcoma. Case
PT
4 shows strong and diffuse, nuclear and cytoplasmic p16 expression (A) with corresponding loss of pRB expression in 100% of the tumor cells (B). Infiltrating lymphocytes show retained pRB
CE
expression. Case 2 shows moderate to strong p16 expression in 60% of the tumor cells (C) with
AC
pRB loss mostly restricted to regions of p16 expression (D, right) and retention of pRB expression in p16 negative areas of the tumor (D, left). (Original magnifications x200 [A,C,D] and x400 [B]).
21
AC
Figure 1
CE
PT
ED
MA
NU SC RI PT
ACCEPTED MANUSCRIPT
22
AC
Figure 2
CE
PT
ED
MA
NU SC RI PT
ACCEPTED MANUSCRIPT
23
ACCEPTED MANUSCRIPT
F
Right tonsil
-
-
2
29
M
Parapharyngeal space
60%
ModerateStrong
3
62
M
Lung
-
-
4
47
F
Rectum
100%
5
55
F
Abdomen
80%
6
42
M
Cervical lymph node
7
35
F
8
43
F
Retained Neck LNs
CR
35
Partial loss (70%)
ED
MA NU S
1
IP
T
Table 1. Clinicopathologic features and immunohistochemistry results in follicular dendritic cell sarcoma Case Age Sex Location p16 IHC pRB Met Treatment (years) IHC Extent Intensity
PT
Strong
None Local resection and lymph node dissection
Retained None
Loss (100%)
Radical resection subsequent lymph node dissection + radiation
Liver
Patient Status (Follow-up) NEOD (16 y)
NEOD (3 m)
Lobectomy (mid + lower) with regional lymph node dissection
NEOD (4 y)
Resection + radiation + adjuvant chemotherapy
AWD (3 y)
Retained None
Resection + adjuvant chemotherapy
NEOD (3 y)
-
-
Retained Lung
Resection + adjuvant chemotherapy
AWD (3 y)
Nasopharynx
80%
Moderate
Retroperitoneum
-
-
AC
CE
WeakStrong
Retained None Local resection and lymph node dissection
NEOD (4 m)
Retained None
NEOD (5 m)
Radical resection + adjuvant chemotherapy
Abbreviations: IHC=immunohistochemistry; F=female; M=male; met=metastasis; LNs=lymph nodes; y=years; NEOD=no evidence of disease; m=months; AWD=alive with disease
24
ACCEPTED MANUSCRIPT Highlights: Follicular dendritic cell sarcomas are rare and frequently misdiagnosed A subset of follicular dendritic cell sarcomas overexpress p16
p16 expression may cause diagnostic confusion with HPV-related oropharyngeal cancer
Dendritic markers and cytokeratins are critical in separating the two entities
AC
CE
PT
ED
MA
NU
SC
RI P
T
25