- Email: [email protected]
Pigmented epithelioid melanocytoma (animal-type melanoma): An institutional experience
ORIGINAL
ARTICLE
Pigmented epithelioid melanocytoma (animal type melanoma): An institutional experience Michael J. Bax, MD,a Marc D. Brown, MD,a Paul G. Rothberg, PhD,b,c Todd S. Laughlin, PhD,b,c and Glynis A. Scott, MDa,b Rochester, New York Background: Pigmented epithelioid melanocytoma (PEM) is an uncommon, recently described entity with unknown biologic behavior. There is a high rate of regional metastases, but limited evidence of distant metastases or disease-related death. Objective: We sought to report our series of patients given a diagnosis of PEM at our institution and provide mutational analysis of genes commonly implicated in melanoma in 2 cases. Methods: The pathology database was queried for cases of PEM diagnosed at the University of Rochester. Charts were reviewed for follow-up information. Mutational analysis of melanoma-associated genes was performed on 2 cases. Results: Nine cases of PEM were retrieved in a 10-year retrospective review. Five patients underwent sentinel lymph node biopsy with 3 of 5 having a positive sentinel lymph node. All 9 patients are alive and disease-free with average follow-up of 38.75 months. Two tumors were tested for common melanomaassociated mutations, and were negative, except for a telomerase reverse transcriptase promoter deletion detected in 1 sample. The deletion has not been associated with melanoma, and therefore its biologic significance is unclear. Limitations: Small sample size, retrospective nature, and single institution experience are limitations. Conclusions: PEM appears to have an indolent behavior. However, currently the evidence is too limited to provide insight into its true biologic potential. ( J Am Acad Dermatol http://dx.doi.org/10.1016/ j.jaad.2017.01.029.) Key words: animal type melanoma; Carney complex; epithelioid blue nevus; melanoma; pigmented epithelioid melanocytoma; sentinel lymph node biopsy.
‘P
igmented epithelioid melanocytoma’’ (PEM) is a term proposed by Zembowicz et al1 in 2004 to describe a distinctive highly pigmented melanocytic lesion that was previously known as ‘‘animal-type melanoma.’’ Histologically indistinguishable from ‘‘epithelioid blue nevus,’’ which is associated with Carney complex, PEM is characterized by nodular aggregates of dermal and subcutaneous, heavily pigmented epithelioid cells with prominent nucleoli and interspersed From the Departments of Dermatology,a Pathology,b and Laboratory Medicine,c University of Rochester School of Medicine. Funding sources: None. Conflicts of interest: None declared. Accepted for publication January 17, 2017.
Abbreviations used: PEM: pigmented epithelioid melanocytoma SLN: sentinel lymph node TERT: telomerase reverse transcriptase
melanophages. The biologic behavior of PEM is generally considered to be low grade, with 1 study demonstrating 46% involvement of regional lymph Reprint requests: Michael J. Bax, MD, Roswell Park Cancer Institute, Elm and Carlton Streets, Buffalo, NY 14263. E-mail: Michael. [email protected]. Published online April 14, 2017. 0190-9622/$36.00 Ó 2017 by the American Academy of Dermatology, Inc. http://dx.doi.org/10.1016/j.jaad.2017.01.029
1
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primer sequences and polymerase chain reaction nodes, but with a very limited propensity for spread conditions are available on request. Material was cut beyond the lymph nodes.1 The tumor is very unfrom the paraffin block (30 M) and genomic DNA common, tends to occur in young people, and, was purified using the QIAamp system (Qiagen Inc, because of its cellularity and atypia, may be mistaken Valencia, CA) according to the manufacturer’s profor conventional melanoma. PEM typically presents clinically as a darkly tocol. Mutations were confirmed by Sanger pigmented, slowly growing nodule in young patients. sequencing. It is usually a dermal tumor with a blue/gray color. It RESULTS CAPSULE SUMMARY occurs on the face, trunk, The clinical characteristics, extremities, and genitalia. pathologic staging, Breslow Pigmented epithelioid melanocytoma is Herein, we describe the clindepth, and follow-up of the a rare neoplasm with a high rate of ical and histopathologic char9 patients with PEM are preregional metastases. acteristics of 9 patients with sented in Table II. Three patPEM treated at the University We report 9 cases of this entity with 3 of ents were females and 6 of Rochester, including these having positive sentinel lymph patients were male. The lymph node status when node biopsy specimens. All patients are average age at diagnosis was available, overall survival, alive and disease-free. 24.7 years. Four of the tumors and mutational analysis for were located on the head and More clinical and molecular data are melanoma-associated mutaneck, 4 on the trunk, and 1 on necessary to better classify this entity. tions in 2 cases. the back of the hand (Fig 1). Three tumors were a pathologic stage T2a, 3 were stage METHODS T3a, and 2 were stage T4a. One tumor could not be This study was approved by the University of staged because the original slides were not available Rochester Research Subjects Review Board. The for review (patient 3). The mean Breslow depth was surgical pathology database at the University of 4.0 mm; however, the depth was skewed by patient 2, Rochester Department of Pathology was queried in whom the Breslow depth was 14 mm (1.4 cm). from 2004 to 2014 for patients with a diagnosis of Excluding this patient, the Breslow depth was PEM. A total of 9 cases were retrieved. The original 2.5 mm. The histologic appearance of the lesions slides were reviewed by a dermatopathologist (G. A. showed classic features of PEM, including heavily S.) for all cases with the exception of case 3, in which pigmented epithelioid cells in the dermis with only the report was available, and each lesion was numerous interspersed melanophages (Fig 2). All of staged according to the 2009 American Joint the lesions were treated with wide local excision. The Committee on Cancer melanoma staging classificaclinical margin of normal-appearing skin taken at tion.2 For patients with sentinel lymph node (SLN) excision was not documented in all cases, but of those biopsy specimens or completion lymphadenectothat were documented, the margin was appropriate mies, lymph nodes were also reviewed. In 2 patients, for a similarly staged conventional melanoma. SLN the paraffin blocks from the primary lesion were biopsies were performed in 5 of 9 patients and were retrieved and DNA was extracted for mutational analysis. Of the 9 patients, 4 were received from the in-house dermatopathology service, and 5 were Table I. Gene regions studied received as consults from other institutions. For patients whose diagnostic biopsy was performed at Gene Region (focus) an outside institution, slides were available for BRAF Codon 700 review in all cases, with the exception of 1 case in GNAQ Codon 209 which the slides from the initial biopsy were not GNA11 Codon 209 SF3B1 Codon 603-790 available. The electronic medical record and patient RAC1 Codon 29 charts were reviewed to determine the age of the NRAS Codons 12, 13, 61 patient at diagnosis, clinical characteristics of the KRAS Codons 12, 13, 61 primary lesion, treatment, and follow-up. HRAS Codons 12, 13, 61 For mutational analysis of melanoma-associated KIT Exons 9, 11, 13, 17 genes, samples in which tumor cells occupied more TP53 Exons 4-10 than 50% of the paraffin block were used from 2 TERT Promoter, e50 to e270 bp from initiator ATG internal cases, without microdissection. Table I shows the genes and mutation sites examined; bp, Base pair; TERT, telomerase reverse transcriptase. d
d
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Table II. Clinical characteristics Case
1 2 3 4 5 6 7 8 9 Mean
Age at diagnosis, y
50 23 19 11 4 15 43 52 6 24.7
Sex
F M M M F F M M M
Location
Lesion size, cm
Breslow depth, mm
Right hand Right buttock Right shoulder Left cheek Back of right neck Back Right scapula Left earlobe Scalp
1 3 NA 0.8 0.3 NA NA NA 0.3
2.3 14 NA* 1.5 3.2 1.95 1.5 3.2 4.7
Pathologic stage
pT3a pT4a NA* pT2a pT3a pT2a pT2a pT3a pT4a
Sentinel lymph node
Declined Positivey Positiveyz Not performed Not performed Negative Negative Not performed Positivex
Follow-up, mo
12.00 15.23 114.57 33.80 52.20 46.47 32.53 32.47 9.50 38.75
Disease status
NED NED NED NED NED NED NED NED NED
F, Female; M, male; NA, not available; NED, no evidence of disease. *Slides from original biopsy not available for review. z 1 of 2 Sentinel lymph nodes positive. y Declined completion lymphadenectomy. x Negative completion lymphadenectomy.
deletion (c.-159_-78del; 81 bp) was identified in patient sample 1.
DISCUSSION
Fig 1. Pigmented epithelioid melanocytoma (PEM). Darkly pigmented nodule on the back of right hand. Saucerization biopsy specimen was interpreted as PEM.
positive in 3 of 5 patients. One of 3 patients with a positive SLN had a particularly large and deeply invasive PEM (pT4a, case 2) with areas of necrosis within the tumor (Fig 3). Unfortunately, the pathologic stage of the PEM from 1 patient with a positive SLN biopsy specimen (patient 3) could not be assessed because the slides were not available for review. Of the 3 patients with a positive SLN biopsy specimen, 1 underwent completion lymphadenectomy with 36 negative lymph nodes. One declined lymphadenectomy but was treated with 1 year of interferon alfa-2b (9 million U 3 times weekly). The third patient declined additional medical or surgical intervention. Follow-up is ongoing and ranges from 9.5 to 114.5 months at the time of preparation of this article. The average duration of follow-up was 38.75 months. All 9 patients are disease-free at this time. Mutational analysis was performed from the primary cutaneous lesions from patients 1 and 4. A telomerase reverse transcriptase (TERT) promoter
In 2004, Zembowicz and colleagues1 reported 41 cases of PEM in 40 patients. Tumors occurred in a wide range of ethnicities and body locations including the trunk, extremities, head and neck, and genitalia. The average age of the patients was 27 years, similar to our series (average age 24.7 years). In our series 60% of patients (3 of 5) had a positive SLN. In the report by Zembowicz et al,1 46% (11 of 24) had regional lymph node metastases, and 1 patient had a metastatic liver lesion. Follow-up was available for 27 of their patients for a mean duration of 32 months, and none died of their disease. In 2009 a follow-up study was published looking at long-term outcomes for 26 patients with sporadically occurring PEM.3 Fifteen of these patients were from the original 2004 study by Zembowicz et al1 and the remaining cases were from Australia. All had at least 3 years of confirmed followup. Nine of the patients were male (35%) and 17 were female (65%). The average age at diagnosis was 20 years, and the mean Breslow depth was 2.2 mm. Eighteen of the 26 patients (69%) underwent SLN sampling and 8 of 18 (44%) had regional metastases. All 8 of the patients with metastatic PEM underwent complete lymphadenectomy and 5 of the 8 (63%) received interferon treatment. Median follow-up was 67 months and all of the patients were alive and free of disease at the time of publication. In our series, an average follow-up of 38.75 months (range 9.5114.5 months) has shown no evidence of disease in any of the patients. Therefore, results of our smaller series, although demonstrating a higher incidence of
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Fig 2. Pigmented epithelioid melanocytoma (PEM). A, Scanning view of PEM from the scalp of a 6-year-old boy (case 9). Sections show a dermal tumor that is heavily pigmented without an epidermal component. Cellular spindle cell population can be seen interspersed among melanophages. B, Higher power of the same tumor shows characteristic spindle cells with large nuclei and very prominent nucleoli. Despite the high cellularity, mitotic figures are rare. (A and B, Hematoxylin-eosin stain; original magnifications: A, 34; B, 340.)
Fig 3. Pigmented epithelioid melanocytoma (PEM). A, Scanning view of PEM from the buttock of a 23-year-old man (case 2). Sections show a cellular heavily pigmented tumor confined to the dermis. B, Higher power shows epithelioid and some spindled cells with abundant melanin, with interspersed melanophages. C, Tumor showed several areas of central necrosis. (A to C, Hematoxylin-eosin stain; original magnifications: A, 34; B and C, 340.)
lymph node metastasis, supports the low-grade nature of PEM, with no patients developing distant metastatic disease. Other than BRAF testing in 2 PEM by Battistella et al,4 to our knowledge no prior studies have examined PEM for melanoma-associated mutations. We tested 2 PEM specimens for mutations encountered in cutaneous melanoma, including V600E/K in BRAF; codon 61 mutations in NRAS and mutations in TP53, RAC1, and the TERT promoter; and genes that are less commonly mutated in melanoma such as KIT, HRAS, and KRAS (Table I). In addition, we tested for mutations found in uveal melanoma including GNAQ, GNA11, and SF3B1.5-15 We did not detect any mutations in the 2 samples analyzed, except for an 81-base pair deletion in the TERT promoter, which was identified in case 1. A set of recurrent mutations in the promoter region of the TERT gene was recently found to be associated with malignant melanoma, basal cell carcinoma, and squamous cell
carcinoma.14-16 This TERT promoter deletion has not been previously reported in melanoma to our knowledge, and was present in only a small fraction (\50%) of the cells. Thus, the functional significance of this mutation is unclear. Although PEM have been equated with blue nevi, the lack of GNAQ/GNA11 mutations suggests that they are a distinct entity, however, analysis of additional cases will be necessary to confirm this. We attempted to test additional specimens, however, we had difficulty obtaining high-quality DNA in part because some of the samples were old, and in part because of melanin contamination in the DNA. Although the panel of melanoma-associated genes tested was comprehensive, we did not test for NF1, and therefore it is possible that PEM may harbor mutations in this important melanoma-associated gene. Although we were only able to examine 2 cases, the negative results of our mutational analysis suggest that PEM may not exhibit any of the
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common mutations associated with malignant melanoma, and favor the notion that PEM is a distinct entity that possesses a different biologic potential. Several studies have analyzed the gene associated with Carney complex in PEM (PRKAR1A; chr 17q2224).17 PRKAR1A gene sequencing and loss of heterozygosity studies showed that although none of the PEM had a PRKAR1A mutation, 5 of the 7 PEM showed loss of heterozygosity for most of the 17q22-24 markers. Although our results and the study by Battistella et al4 suggest that PEM lack mutations common in melanoma, a larger sample size is needed to fully elucidate the mutational profile of PEM, including analysis of NF1. However, these preliminary studies suggest that PEM is genetically distinct from conventional cutaneous melanomas. Conclusion PEM is a rare tumor with a predilection for young people. Although reports are rather limited, there is evidence to support the notion that the tumor follows an indolent clinical course, with very low risk of spread beyond regional lymph nodes. Of patients who underwent SLN biopsies, 60% of patients in the current series and 46% of patients in the series of Zembowicz et al1 exhibited lymph node metastases, supporting a high rate of regional spread. There has been only 1 documented case of a distant metastasis of PEM to the liver.1 However, the overall survival is excellent with no cases of death attributed to PEM. As additional clinical and molecular data become available we will be better able to classify these ambiguous neoplasms. REFERENCES 1. Zembowicz A, Carney JA, Mihm MC. Pigmented epithelioid melanocytoma: a low-grade melanocytic tumor with metastatic potential indistinguishable from animal-type melanoma and epithelioid blue nevus. Am J Surg Pathol. 2004;28:31-40. 2. Balch CM, Gershenwald JE, Soong SJ, et al. Final version of 2009 AJCC melanoma staging and classification. J Clin Oncol. 2009;27:6199-6206.
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3. Mandal RV, Murali R, Lundquist KF, et al. Pigmented epithelioid melanocytoma: favorable outcome after 5-year follow-up. Am J Surg Pathol. 2009;33:1778-1782. 4. Battistella M, Prochazkova-Carlotti M, Berrebi D, et al. Two congenital cases of pigmented epithelioid melanocytoma studied by fluorescent in situ hybridization for melanocytic tumors: case reports and review of these recent topics. Dermatology. 2010;221:97-106. 5. Van Raamsdonk CD, Bezrookove V, Green G, et al. Frequent somatic mutations of GNAQ in uveal melanoma and blue nevi. Nature. 2009;457:599-602. 6. Van Raamsdonk CD, Griewank KG, Crosby MB, et al. Mutations in GNA11 in uveal melanoma. N Engl J Med. 2010;363:2191-2199. 7. Harbour JW, Roberson ED, Anbunathan H, Onken MD, Worley LA, Bowcock AM. Recurrent mutations at codon 625 of the splicing factor SF3B1 in uveal melanoma. Nat Genet. 2013;45:133-135. 8. Krauthammer M, Kong Y, Ha BH, et al. Exome sequencing identifies recurrent somatic RAC1 mutations in melanoma. Nat Genet. 2012;44:1006-1014. 9. Van’t Veer LJ, Burgering BM, Versteeg R, et al. N-ras mutations in human cutaneous melanoma from sun-exposed body sites. Mol Cell Biol. 1989;9:3114-3116. 10. Dadzie OE, Yang S, Emley A, Keady M, Bhawan J, Mahalingam M. RAS and RAF mutations in banal melanocytic aggregates contiguous with primary cutaneous melanoma: clues to melanomagenesis. Br J Dermatol. 2009;160: 368-375. 11. Bastian BC, LeBoit PE, Pinkel D. Mutations and copy number increase of HRAS in Spitz nevi with distinctive histopathological features. Am J Pathol. 2000;157:967-972. 12. Curtin JA, Busam K, Pinkel D, Bastian BC. Somatic activation of KIT in distinct subtypes of melanoma. J Clin Oncol. 2006;24: 4340-4346. 13. Weiss J, Cavenee WK, Herbst RA, Jung EG, Arden KC. Point mutations and allelic loss in the TP53 locus of cutaneous malignant melanomas. Arch Dermatol Res. 1994;286: 417-419. 14. Horn S, Figl A, Rachakonda PS, et al. TERT promoter mutations in familial and sporadic melanoma. Science. 2013;339:959-961. 15. Huang FW, Hodis E, Xu MJ, Kryukov GV, Chin L, Garraway LA. Highly recurrent TERT promoter mutations in human melanoma. Science. 2013;339:957-959. 16. Scott GA, Laughlin TS, Rothberg PG. Mutations of the TERT promoter are common in basal cell carcinoma and squamous cell carcinoma. Mod Pathol. 2014;27:516-523. 17. Zembowicz A, Knoepp SM, Bei T, et al. Loss of expression of protein kinase a regulatory subunit 1alpha in pigmented epithelioid melanocytoma but not in melanoma or other melanocytic lesions. Am J Surg Pathol. 2007;31: 1764-1775.
ARTICLE
Pigmented epithelioid melanocytoma (animal type melanoma): An institutional experience Michael J. Bax, MD,a Marc D. Brown, MD,a Paul G. Rothberg, PhD,b,c Todd S. Laughlin, PhD,b,c and Glynis A. Scott, MDa,b Rochester, New York Background: Pigmented epithelioid melanocytoma (PEM) is an uncommon, recently described entity with unknown biologic behavior. There is a high rate of regional metastases, but limited evidence of distant metastases or disease-related death. Objective: We sought to report our series of patients given a diagnosis of PEM at our institution and provide mutational analysis of genes commonly implicated in melanoma in 2 cases. Methods: The pathology database was queried for cases of PEM diagnosed at the University of Rochester. Charts were reviewed for follow-up information. Mutational analysis of melanoma-associated genes was performed on 2 cases. Results: Nine cases of PEM were retrieved in a 10-year retrospective review. Five patients underwent sentinel lymph node biopsy with 3 of 5 having a positive sentinel lymph node. All 9 patients are alive and disease-free with average follow-up of 38.75 months. Two tumors were tested for common melanomaassociated mutations, and were negative, except for a telomerase reverse transcriptase promoter deletion detected in 1 sample. The deletion has not been associated with melanoma, and therefore its biologic significance is unclear. Limitations: Small sample size, retrospective nature, and single institution experience are limitations. Conclusions: PEM appears to have an indolent behavior. However, currently the evidence is too limited to provide insight into its true biologic potential. ( J Am Acad Dermatol http://dx.doi.org/10.1016/ j.jaad.2017.01.029.) Key words: animal type melanoma; Carney complex; epithelioid blue nevus; melanoma; pigmented epithelioid melanocytoma; sentinel lymph node biopsy.
‘P
igmented epithelioid melanocytoma’’ (PEM) is a term proposed by Zembowicz et al1 in 2004 to describe a distinctive highly pigmented melanocytic lesion that was previously known as ‘‘animal-type melanoma.’’ Histologically indistinguishable from ‘‘epithelioid blue nevus,’’ which is associated with Carney complex, PEM is characterized by nodular aggregates of dermal and subcutaneous, heavily pigmented epithelioid cells with prominent nucleoli and interspersed From the Departments of Dermatology,a Pathology,b and Laboratory Medicine,c University of Rochester School of Medicine. Funding sources: None. Conflicts of interest: None declared. Accepted for publication January 17, 2017.
Abbreviations used: PEM: pigmented epithelioid melanocytoma SLN: sentinel lymph node TERT: telomerase reverse transcriptase
melanophages. The biologic behavior of PEM is generally considered to be low grade, with 1 study demonstrating 46% involvement of regional lymph Reprint requests: Michael J. Bax, MD, Roswell Park Cancer Institute, Elm and Carlton Streets, Buffalo, NY 14263. E-mail: Michael. [email protected]. Published online April 14, 2017. 0190-9622/$36.00 Ó 2017 by the American Academy of Dermatology, Inc. http://dx.doi.org/10.1016/j.jaad.2017.01.029
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primer sequences and polymerase chain reaction nodes, but with a very limited propensity for spread conditions are available on request. Material was cut beyond the lymph nodes.1 The tumor is very unfrom the paraffin block (30 M) and genomic DNA common, tends to occur in young people, and, was purified using the QIAamp system (Qiagen Inc, because of its cellularity and atypia, may be mistaken Valencia, CA) according to the manufacturer’s profor conventional melanoma. PEM typically presents clinically as a darkly tocol. Mutations were confirmed by Sanger pigmented, slowly growing nodule in young patients. sequencing. It is usually a dermal tumor with a blue/gray color. It RESULTS CAPSULE SUMMARY occurs on the face, trunk, The clinical characteristics, extremities, and genitalia. pathologic staging, Breslow Pigmented epithelioid melanocytoma is Herein, we describe the clindepth, and follow-up of the a rare neoplasm with a high rate of ical and histopathologic char9 patients with PEM are preregional metastases. acteristics of 9 patients with sented in Table II. Three patPEM treated at the University We report 9 cases of this entity with 3 of ents were females and 6 of Rochester, including these having positive sentinel lymph patients were male. The lymph node status when node biopsy specimens. All patients are average age at diagnosis was available, overall survival, alive and disease-free. 24.7 years. Four of the tumors and mutational analysis for were located on the head and More clinical and molecular data are melanoma-associated mutaneck, 4 on the trunk, and 1 on necessary to better classify this entity. tions in 2 cases. the back of the hand (Fig 1). Three tumors were a pathologic stage T2a, 3 were stage METHODS T3a, and 2 were stage T4a. One tumor could not be This study was approved by the University of staged because the original slides were not available Rochester Research Subjects Review Board. The for review (patient 3). The mean Breslow depth was surgical pathology database at the University of 4.0 mm; however, the depth was skewed by patient 2, Rochester Department of Pathology was queried in whom the Breslow depth was 14 mm (1.4 cm). from 2004 to 2014 for patients with a diagnosis of Excluding this patient, the Breslow depth was PEM. A total of 9 cases were retrieved. The original 2.5 mm. The histologic appearance of the lesions slides were reviewed by a dermatopathologist (G. A. showed classic features of PEM, including heavily S.) for all cases with the exception of case 3, in which pigmented epithelioid cells in the dermis with only the report was available, and each lesion was numerous interspersed melanophages (Fig 2). All of staged according to the 2009 American Joint the lesions were treated with wide local excision. The Committee on Cancer melanoma staging classificaclinical margin of normal-appearing skin taken at tion.2 For patients with sentinel lymph node (SLN) excision was not documented in all cases, but of those biopsy specimens or completion lymphadenectothat were documented, the margin was appropriate mies, lymph nodes were also reviewed. In 2 patients, for a similarly staged conventional melanoma. SLN the paraffin blocks from the primary lesion were biopsies were performed in 5 of 9 patients and were retrieved and DNA was extracted for mutational analysis. Of the 9 patients, 4 were received from the in-house dermatopathology service, and 5 were Table I. Gene regions studied received as consults from other institutions. For patients whose diagnostic biopsy was performed at Gene Region (focus) an outside institution, slides were available for BRAF Codon 700 review in all cases, with the exception of 1 case in GNAQ Codon 209 which the slides from the initial biopsy were not GNA11 Codon 209 SF3B1 Codon 603-790 available. The electronic medical record and patient RAC1 Codon 29 charts were reviewed to determine the age of the NRAS Codons 12, 13, 61 patient at diagnosis, clinical characteristics of the KRAS Codons 12, 13, 61 primary lesion, treatment, and follow-up. HRAS Codons 12, 13, 61 For mutational analysis of melanoma-associated KIT Exons 9, 11, 13, 17 genes, samples in which tumor cells occupied more TP53 Exons 4-10 than 50% of the paraffin block were used from 2 TERT Promoter, e50 to e270 bp from initiator ATG internal cases, without microdissection. Table I shows the genes and mutation sites examined; bp, Base pair; TERT, telomerase reverse transcriptase. d
d
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Table II. Clinical characteristics Case
1 2 3 4 5 6 7 8 9 Mean
Age at diagnosis, y
50 23 19 11 4 15 43 52 6 24.7
Sex
F M M M F F M M M
Location
Lesion size, cm
Breslow depth, mm
Right hand Right buttock Right shoulder Left cheek Back of right neck Back Right scapula Left earlobe Scalp
1 3 NA 0.8 0.3 NA NA NA 0.3
2.3 14 NA* 1.5 3.2 1.95 1.5 3.2 4.7
Pathologic stage
pT3a pT4a NA* pT2a pT3a pT2a pT2a pT3a pT4a
Sentinel lymph node
Declined Positivey Positiveyz Not performed Not performed Negative Negative Not performed Positivex
Follow-up, mo
12.00 15.23 114.57 33.80 52.20 46.47 32.53 32.47 9.50 38.75
Disease status
NED NED NED NED NED NED NED NED NED
F, Female; M, male; NA, not available; NED, no evidence of disease. *Slides from original biopsy not available for review. z 1 of 2 Sentinel lymph nodes positive. y Declined completion lymphadenectomy. x Negative completion lymphadenectomy.
deletion (c.-159_-78del; 81 bp) was identified in patient sample 1.
DISCUSSION
Fig 1. Pigmented epithelioid melanocytoma (PEM). Darkly pigmented nodule on the back of right hand. Saucerization biopsy specimen was interpreted as PEM.
positive in 3 of 5 patients. One of 3 patients with a positive SLN had a particularly large and deeply invasive PEM (pT4a, case 2) with areas of necrosis within the tumor (Fig 3). Unfortunately, the pathologic stage of the PEM from 1 patient with a positive SLN biopsy specimen (patient 3) could not be assessed because the slides were not available for review. Of the 3 patients with a positive SLN biopsy specimen, 1 underwent completion lymphadenectomy with 36 negative lymph nodes. One declined lymphadenectomy but was treated with 1 year of interferon alfa-2b (9 million U 3 times weekly). The third patient declined additional medical or surgical intervention. Follow-up is ongoing and ranges from 9.5 to 114.5 months at the time of preparation of this article. The average duration of follow-up was 38.75 months. All 9 patients are disease-free at this time. Mutational analysis was performed from the primary cutaneous lesions from patients 1 and 4. A telomerase reverse transcriptase (TERT) promoter
In 2004, Zembowicz and colleagues1 reported 41 cases of PEM in 40 patients. Tumors occurred in a wide range of ethnicities and body locations including the trunk, extremities, head and neck, and genitalia. The average age of the patients was 27 years, similar to our series (average age 24.7 years). In our series 60% of patients (3 of 5) had a positive SLN. In the report by Zembowicz et al,1 46% (11 of 24) had regional lymph node metastases, and 1 patient had a metastatic liver lesion. Follow-up was available for 27 of their patients for a mean duration of 32 months, and none died of their disease. In 2009 a follow-up study was published looking at long-term outcomes for 26 patients with sporadically occurring PEM.3 Fifteen of these patients were from the original 2004 study by Zembowicz et al1 and the remaining cases were from Australia. All had at least 3 years of confirmed followup. Nine of the patients were male (35%) and 17 were female (65%). The average age at diagnosis was 20 years, and the mean Breslow depth was 2.2 mm. Eighteen of the 26 patients (69%) underwent SLN sampling and 8 of 18 (44%) had regional metastases. All 8 of the patients with metastatic PEM underwent complete lymphadenectomy and 5 of the 8 (63%) received interferon treatment. Median follow-up was 67 months and all of the patients were alive and free of disease at the time of publication. In our series, an average follow-up of 38.75 months (range 9.5114.5 months) has shown no evidence of disease in any of the patients. Therefore, results of our smaller series, although demonstrating a higher incidence of
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Fig 2. Pigmented epithelioid melanocytoma (PEM). A, Scanning view of PEM from the scalp of a 6-year-old boy (case 9). Sections show a dermal tumor that is heavily pigmented without an epidermal component. Cellular spindle cell population can be seen interspersed among melanophages. B, Higher power of the same tumor shows characteristic spindle cells with large nuclei and very prominent nucleoli. Despite the high cellularity, mitotic figures are rare. (A and B, Hematoxylin-eosin stain; original magnifications: A, 34; B, 340.)
Fig 3. Pigmented epithelioid melanocytoma (PEM). A, Scanning view of PEM from the buttock of a 23-year-old man (case 2). Sections show a cellular heavily pigmented tumor confined to the dermis. B, Higher power shows epithelioid and some spindled cells with abundant melanin, with interspersed melanophages. C, Tumor showed several areas of central necrosis. (A to C, Hematoxylin-eosin stain; original magnifications: A, 34; B and C, 340.)
lymph node metastasis, supports the low-grade nature of PEM, with no patients developing distant metastatic disease. Other than BRAF testing in 2 PEM by Battistella et al,4 to our knowledge no prior studies have examined PEM for melanoma-associated mutations. We tested 2 PEM specimens for mutations encountered in cutaneous melanoma, including V600E/K in BRAF; codon 61 mutations in NRAS and mutations in TP53, RAC1, and the TERT promoter; and genes that are less commonly mutated in melanoma such as KIT, HRAS, and KRAS (Table I). In addition, we tested for mutations found in uveal melanoma including GNAQ, GNA11, and SF3B1.5-15 We did not detect any mutations in the 2 samples analyzed, except for an 81-base pair deletion in the TERT promoter, which was identified in case 1. A set of recurrent mutations in the promoter region of the TERT gene was recently found to be associated with malignant melanoma, basal cell carcinoma, and squamous cell
carcinoma.14-16 This TERT promoter deletion has not been previously reported in melanoma to our knowledge, and was present in only a small fraction (\50%) of the cells. Thus, the functional significance of this mutation is unclear. Although PEM have been equated with blue nevi, the lack of GNAQ/GNA11 mutations suggests that they are a distinct entity, however, analysis of additional cases will be necessary to confirm this. We attempted to test additional specimens, however, we had difficulty obtaining high-quality DNA in part because some of the samples were old, and in part because of melanin contamination in the DNA. Although the panel of melanoma-associated genes tested was comprehensive, we did not test for NF1, and therefore it is possible that PEM may harbor mutations in this important melanoma-associated gene. Although we were only able to examine 2 cases, the negative results of our mutational analysis suggest that PEM may not exhibit any of the
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common mutations associated with malignant melanoma, and favor the notion that PEM is a distinct entity that possesses a different biologic potential. Several studies have analyzed the gene associated with Carney complex in PEM (PRKAR1A; chr 17q2224).17 PRKAR1A gene sequencing and loss of heterozygosity studies showed that although none of the PEM had a PRKAR1A mutation, 5 of the 7 PEM showed loss of heterozygosity for most of the 17q22-24 markers. Although our results and the study by Battistella et al4 suggest that PEM lack mutations common in melanoma, a larger sample size is needed to fully elucidate the mutational profile of PEM, including analysis of NF1. However, these preliminary studies suggest that PEM is genetically distinct from conventional cutaneous melanomas. Conclusion PEM is a rare tumor with a predilection for young people. Although reports are rather limited, there is evidence to support the notion that the tumor follows an indolent clinical course, with very low risk of spread beyond regional lymph nodes. Of patients who underwent SLN biopsies, 60% of patients in the current series and 46% of patients in the series of Zembowicz et al1 exhibited lymph node metastases, supporting a high rate of regional spread. There has been only 1 documented case of a distant metastasis of PEM to the liver.1 However, the overall survival is excellent with no cases of death attributed to PEM. As additional clinical and molecular data become available we will be better able to classify these ambiguous neoplasms. REFERENCES 1. Zembowicz A, Carney JA, Mihm MC. Pigmented epithelioid melanocytoma: a low-grade melanocytic tumor with metastatic potential indistinguishable from animal-type melanoma and epithelioid blue nevus. Am J Surg Pathol. 2004;28:31-40. 2. Balch CM, Gershenwald JE, Soong SJ, et al. Final version of 2009 AJCC melanoma staging and classification. J Clin Oncol. 2009;27:6199-6206.
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3. Mandal RV, Murali R, Lundquist KF, et al. Pigmented epithelioid melanocytoma: favorable outcome after 5-year follow-up. Am J Surg Pathol. 2009;33:1778-1782. 4. Battistella M, Prochazkova-Carlotti M, Berrebi D, et al. Two congenital cases of pigmented epithelioid melanocytoma studied by fluorescent in situ hybridization for melanocytic tumors: case reports and review of these recent topics. Dermatology. 2010;221:97-106. 5. Van Raamsdonk CD, Bezrookove V, Green G, et al. Frequent somatic mutations of GNAQ in uveal melanoma and blue nevi. Nature. 2009;457:599-602. 6. Van Raamsdonk CD, Griewank KG, Crosby MB, et al. Mutations in GNA11 in uveal melanoma. N Engl J Med. 2010;363:2191-2199. 7. Harbour JW, Roberson ED, Anbunathan H, Onken MD, Worley LA, Bowcock AM. Recurrent mutations at codon 625 of the splicing factor SF3B1 in uveal melanoma. Nat Genet. 2013;45:133-135. 8. Krauthammer M, Kong Y, Ha BH, et al. Exome sequencing identifies recurrent somatic RAC1 mutations in melanoma. Nat Genet. 2012;44:1006-1014. 9. Van’t Veer LJ, Burgering BM, Versteeg R, et al. N-ras mutations in human cutaneous melanoma from sun-exposed body sites. Mol Cell Biol. 1989;9:3114-3116. 10. Dadzie OE, Yang S, Emley A, Keady M, Bhawan J, Mahalingam M. RAS and RAF mutations in banal melanocytic aggregates contiguous with primary cutaneous melanoma: clues to melanomagenesis. Br J Dermatol. 2009;160: 368-375. 11. Bastian BC, LeBoit PE, Pinkel D. Mutations and copy number increase of HRAS in Spitz nevi with distinctive histopathological features. Am J Pathol. 2000;157:967-972. 12. Curtin JA, Busam K, Pinkel D, Bastian BC. Somatic activation of KIT in distinct subtypes of melanoma. J Clin Oncol. 2006;24: 4340-4346. 13. Weiss J, Cavenee WK, Herbst RA, Jung EG, Arden KC. Point mutations and allelic loss in the TP53 locus of cutaneous malignant melanomas. Arch Dermatol Res. 1994;286: 417-419. 14. Horn S, Figl A, Rachakonda PS, et al. TERT promoter mutations in familial and sporadic melanoma. Science. 2013;339:959-961. 15. Huang FW, Hodis E, Xu MJ, Kryukov GV, Chin L, Garraway LA. Highly recurrent TERT promoter mutations in human melanoma. Science. 2013;339:957-959. 16. Scott GA, Laughlin TS, Rothberg PG. Mutations of the TERT promoter are common in basal cell carcinoma and squamous cell carcinoma. Mod Pathol. 2014;27:516-523. 17. Zembowicz A, Knoepp SM, Bei T, et al. Loss of expression of protein kinase a regulatory subunit 1alpha in pigmented epithelioid melanocytoma but not in melanoma or other melanocytic lesions. Am J Surg Pathol. 2007;31: 1764-1775.