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Mucoepidermoid carcinoma ex-inverted papilloma
INSTRUCTIVE CASE
Mucoepidermoid carcinoma ex-inverted papilloma
papilloma, inverted (endophytic) papilloma, and oncocytic (cylindrical cell) papilloma.1 Transformation to squamous cell carcinomas has been reported to occur in up to 2% of sinonasal papillomas,2,3 with the vast majority of such cases occurring in inverted papillomas. Transformation to other types of carcinomas is much less frequent with reported cases including sinonasal type undifferentiated carcinoma, mucoepidermoid carcinoma, adenocarcinoma NOS, and small cell neuroendocrine carcinoma.1,2,3
Martin D Hyrcza Ralph W Gilbert Eugene Yu ~ez Bayardo Perez-Ordon
Case report
Abstract
The patient is a 43-year old woman who presented to the ocular clinic with a one-year history of pain over the bridge of the nose which radiated bilaterally to the premaxillary region. She denied any ocular symptoms or epistaxis, although she reported coughing up nasal secretions mixed with blood on several occasions. Her past medical history included hepatitis C, intravenous drug use, back trauma and ovarian cystectomy. MR imaging at presentation showed a large nasal cavity mass extending into the anterior left ethmoid air cells, the left nasolacrimal canal and lacrimal sac, and through the left lacrimal bone into the orbit. The signal characteristics were suggestive of a cellular tumour such as inverted papilloma or carcinoma. Transnasal debulking of the nasal portion of the lesion was performed and the surgical specimen showed inverted Schneiderian papilloma without malignant transformation. The patient’s symptoms persisted after her initial surgery and a follow-up CT scan showed residual tumour in the left ethmoid and the maxillary sinuses, the left lacrimal sac as well as the left medial orbit (Figure 1). The orbital portion of the tumour was resected at a different institution through a left posterior orbitotomy and medial canthopexy. The pathology specimen from that resection showed papillomatous light pink tumour fragments of inverted papilloma with numerous mucous cells. Re-excision of the sinonasal mass was performed via external-approach rhinotomy, left medial maxillectomy, left sphenoidectomy and ethmoidectomy. The specimen resected during this last surgical resection was reported as “low-grade mucoepidermoid carcinoma ex-inverted papilloma”. The patient underwent adjuvant radiotherapy and is well with no tumour recurrence 9 months after her last surgery. Gross examination showed papillary pink, tan, and white tissue fragments admixed with membranous mucosal and bone fragments. Microscopic examination showed the lesion consisting predominantly of a thickened, multilayered non-keratinizing squamous epithelium replacing normal respiratory mucosa, and seromucous glands and ducts. The neoplastic cells showed an inverted or endophytic growth pattern extending into the underlying stroma consistent with inverted Schneiderian papilloma (Figure 2a); however, admixed with the squamous epithelium were a large number of mucous and goblet cells (Figure 2b), more than would be expected in an inverted papilloma. Additionally, multiple foci of cytologic atypia, nuclear pleomorphism (Figure 2c) and invasion of the bone were noted (Figure 2d). These microscopic findings, taken together with the aggressive nature of the tumour and its high rate of growth, caused the
Mucoepidermoid carcinoma (MEC) typically arises from major salivary glands, minor salivary glands of the oral cavity and mucous glands of the aerodigestive tract. Cases of MEC arising from benign sinonasal or lacrimal papillomas are extremely rare. Herein we describe a MEC representing malignant transformation of an inverted Schneiderian papilloma. The patient presented with nasal bridge pain radiating to the premaxillary regions. Imaging showed a tumour involving the left nasal cavity, left ethmoid and maxillary sinuses and extending into the left orbit and lacrimal sac. Initial biopsy and debulking specimens showed only inverted papilloma. The re-excision specimen demonstrated a tumour with features of both inverted papilloma and MEC that superficially invaded bone. The tumour was negative for MECT1-MAML2 translocation. Linear array analysis of tumour tissue demonstrated the presence of human papillomavirus-11 (HPV-11).
Keywords inverted Schneiderian papilloma; lacrimal system; mucoepidermoid carcinoma; sinonasal tract
Introduction Schneiderian mucosa lines most of the paranasal sinuses and the nasal cavity with the exception of the nasal vestibule and the roof of the nose, which are lined by stratified squamous epithelium and olfactory mucosa respectively. Three benign neoplastic papillomatous neoplasms arise from the Schneiderian membrane: exophytic (also referred to as fungiform or everted)
Martin D Hyrcza MD Resident, Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada. Conflicts of interest: none declared. Ralph W Gilbert MD FRCSC Professor, Department of OtolaryngologyHead and Neck Surgery/Surgical Oncology, Wharton Head and Neck Program, University Health Network, Princess Margaret Hospital, Toronto, Ontario, Canada. Conflicts of interest: none declared. Eugene Yu MD FRCPC Associate Professor, Joint Department of Medical Imaging of Mount Sinai Hospital and University Health Network and Department of Medical Imaging, University of Toronto, Ontario, Canada. Conflicts of interest: none declared. ~ez MD FRCPC Associate Professor, Department of Bayardo Perez-Ordon Pathology, University Health Network, and Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada. Conflicts of interest: none declared.
DIAGNOSTIC HISTOPATHOLOGY --:-
1
Ó 2015 Elsevier Ltd. All rights reserved.
Please cite this article in press as: Hyrcza MD, et al., Mucoepidermoid carcinoma ex-inverted papilloma, Diagnostic Histopathology (2015), http:// dx.doi.org/10.1016/j.mpdhp.2015.06.002
INSTRUCTIVE CASE
Figure 1 Axial and coronal T1 weighted post gadolinium enhanced images demonstrates mild enhancement of the left anterior ethmoid region mass that has extended into and is enlarging the nasolacrimal sac fossa.
classification of this tumour as a low grade mucoepidermoid carcinoma arising from an inverted Schneiderian papilloma (i.e. a low grade mucoepidermoid carcinoma ex-inverted Schneiderian papilloma).
Immunohistochemistry for p16 showed strong but heterogeneous staining in about 30% of the tumour cells (Figure 3a). Ki67 labeling index was approximately 20% (Figure 3b). HPV molecular testing by Linear Array demonstrated the presence of
Figure 2 Papillomatous area composed of non-keratinizing squamous epithelium with an endophytic grow pattern (a). Invasive carcinoma composed of atypical non-keratinizing squamous cells and numerous mucous goblet cells (b). Atypical squamous cells showing hyperchromatic and pleomorphic nuclei (c). Focus of mucoepidermoid carcinoma close to trabeculae of ethmoid bone (d).
DIAGNOSTIC HISTOPATHOLOGY --:-
2
Ó 2015 Elsevier Ltd. All rights reserved.
Please cite this article in press as: Hyrcza MD, et al., Mucoepidermoid carcinoma ex-inverted papilloma, Diagnostic Histopathology (2015), http:// dx.doi.org/10.1016/j.mpdhp.2015.06.002
INSTRUCTIVE CASE
Figure 3 Diffuse expression of p16 in the tumour cells (a). MIB-1 proliferative index of approximately 20% (b).
transformation of the background papilloma, this is not likely with a low grade mucoepidermoid carcinoma whose squamous component can merge seamlessly with the background papilloma. The diagnosis, as in our case, rests on the clinically demonstrated aggressive growth combined with microscopically demonstrated bony invasion, cytologic atypia, and typical mucoepidermoid architecture and cytology. Molecular testing for MECT1-MAML2 rearrangement can be performed if in doubt, although a negative result does not exclude the diagnosis as only w50e66 % of MECs harbor the translocation.6 The presence of HPV11 in inverted papillomas has been described previously, with a reported prevalence of 30%.7 It is likely then that the inverted papilloma in which the MEC arose already carried the infection. However, there is no evidence that the virus is associated with malignant transformation. The low risk HPVs such as HPV11 do not inactivate the Rb protein, which regulates p16 protein expression. Thus, tissues infected with HPV11 tend to show weak and patchy p16 staining. The strong but patchy p16 expression in this tumour is therefore likely a result of the molecular changes occurring during the malignant transformation and unrelated to the presence of HPV11. In the study of 20 carcinomas ex-Schneiderian papillomas, Nudell et al. report 3 cases showing strong positivity in 20e40% of cells and an additional 5 cases with strong, diffuse positivity in >70% of cells. Only 3 of these 8 cases were HPV ISH positive.2 A
HPV-11 DNA in the tumour. The tumour was tested for MAML2 rearrangements by split-apart fluorescence in-situ hybridization (FISH) which was negative.
Discussion Mucoepidermoid carcinoma (MEC) most commonly arises in major salivary glands and minor salivary glands of the oral cavity and the respiratory tract. It is also known to occasionally arise from the major and minor lacrimal glands of the orbit and in the nasolacrimal system. Finding of mucoepidermoid carcinoma arising from a Schneiderian papilloma is rare. In his recent examination of 20 cases of carcinomas arising in Schneiderian papillomas, Nudell et al. reported two cases of MEC, both high grade.2 The majority of the other 18 cases involved squamous cell carcinomas. Kapadia et al. reported two cases of MEC arising from oncocytic (cylindrical cell) Schneiderian papilloma out of six cases of malignant transformation in this type of the tumour found in the Armed Forces Institute of Pathology archives.4 Our review of literature revealed another case of mucoepidermoid carcinoma arising from previously resected squamous papilloma of the lacrimal sac,5 bringing the total of published cases of this entity to five. The diagnosis of low-grade mucoepidermoid carcinoma exSchneiderian papilloma may be a challenge for several reasons. First, inverted papillomas are known to contain mucous and goblet cells individually or forming small clusters1 thus their presence alone is not sufficient to suspect transformation to MEC. In our case the mucous cells were present extensively throughout the lesion and not just focally. Second, inverted papillomas, despite being benign neoplasms, sometimes behave locally aggressive with extension into local structures such as the sinuses, the nasolacrimal system and the orbit, as seen in this case. Thus, aggressive behaviour alone is not sufficient to suspect malignant transformation, although it should prompt a careful search for other atypical features. Third, minor foci of cytologic atypia can be observed in Schneiderian papillomas, especially in areas of inflammation, and are typically without any clinical significance. An additional difficulty involves the low grade of the carcinoma, whereas large areas of high grade MEC would likely stand out and be relatively easily diagnosed as
DIAGNOSTIC HISTOPATHOLOGY --:-
REFERENCES ~ez B. Hamartomas, papillomas and adenocarcinomas of 1 Perez-Ordon the sinonasal tract and nasopharynx. J Clin Pathol 2009; 62: 1085e95. 2 Nudell J, Chiosea S, Thompson LDR. Carcinoma ex-Schneiderian papilloma (malignant transformation): a clinicopathologic and immunophenotypic study of 20 cases combined with a comprehensive review of the literature. Head Neck Pathol 2014; 8: 269e86. 3 Wolfish EB, Nelson BL, Thompson LDR. Sinonasal tract mucoepidermoid carcinoma: a clinicopathological and immunophenotypic study of 19 cases combined with a comprehensive review of the literature. Head Neck Pathol 2012; 6: 191e207.
3
Ó 2015 Elsevier Ltd. All rights reserved.
Please cite this article in press as: Hyrcza MD, et al., Mucoepidermoid carcinoma ex-inverted papilloma, Diagnostic Histopathology (2015), http:// dx.doi.org/10.1016/j.mpdhp.2015.06.002
INSTRUCTIVE CASE
4 Kapadia SB, Barnes L, Pelzman K, Mirani N, Heffner DK, Bedetti C. Carcinoma ex oncocytic Schneiderian (cylindrical cell) papilloma. Am J Otolaryngol 1993; 14: 332e8. 5 Lee SB, Kim KN, Lee SR, Bernardino CR. Mucoepidermoid carcinoma of the lacrimal sac after dacryocystectomy for squamous papilloma. Ophthal Plast Reconstr Surg 2011; 27: e44e6. 6 Seethala RR, Dacic S, Cieply K, Kelly LM, Nikiforova MN. A reappraisal of the MECT1/MAML2 translocation in salivary mucoepidermoid carcinomas. Am J Surg Pathol 2010; 34: 1106e21. 7 Shen J, Tate JE, Crum CP, Goodman ML. Prevalence of human papillomaviruses (HPV) in benign and malignant tumors of the upper respiratory tract. Mod Pathol 1996; 9: 15e20.
Practice points C
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DIAGNOSTIC HISTOPATHOLOGY --:-
4
Malignant transformation of inverted Schneiderian papillomas is a well recognized complication therefore proper sampling and careful examination of these lesions is necessary to avoid delays in their pathologic diagnosis The most common carcinoma arising in inverted Schneiderian papillomas are squamous cell carcinoma; however, rare examples of mucoepidermoid carcinoma, sinonasal type undifferentiated carcinoma and high-grade neuroendocrine carcinoma (small celltype) have also been described The molecular mechanisms, including the role played by HPV, underpinning the malignant transformation of inverted Schneiderian papilloma are not known
Ó 2015 Elsevier Ltd. All rights reserved.
Please cite this article in press as: Hyrcza MD, et al., Mucoepidermoid carcinoma ex-inverted papilloma, Diagnostic Histopathology (2015), http:// dx.doi.org/10.1016/j.mpdhp.2015.06.002
Mucoepidermoid carcinoma ex-inverted papilloma
papilloma, inverted (endophytic) papilloma, and oncocytic (cylindrical cell) papilloma.1 Transformation to squamous cell carcinomas has been reported to occur in up to 2% of sinonasal papillomas,2,3 with the vast majority of such cases occurring in inverted papillomas. Transformation to other types of carcinomas is much less frequent with reported cases including sinonasal type undifferentiated carcinoma, mucoepidermoid carcinoma, adenocarcinoma NOS, and small cell neuroendocrine carcinoma.1,2,3
Martin D Hyrcza Ralph W Gilbert Eugene Yu ~ez Bayardo Perez-Ordon
Case report
Abstract
The patient is a 43-year old woman who presented to the ocular clinic with a one-year history of pain over the bridge of the nose which radiated bilaterally to the premaxillary region. She denied any ocular symptoms or epistaxis, although she reported coughing up nasal secretions mixed with blood on several occasions. Her past medical history included hepatitis C, intravenous drug use, back trauma and ovarian cystectomy. MR imaging at presentation showed a large nasal cavity mass extending into the anterior left ethmoid air cells, the left nasolacrimal canal and lacrimal sac, and through the left lacrimal bone into the orbit. The signal characteristics were suggestive of a cellular tumour such as inverted papilloma or carcinoma. Transnasal debulking of the nasal portion of the lesion was performed and the surgical specimen showed inverted Schneiderian papilloma without malignant transformation. The patient’s symptoms persisted after her initial surgery and a follow-up CT scan showed residual tumour in the left ethmoid and the maxillary sinuses, the left lacrimal sac as well as the left medial orbit (Figure 1). The orbital portion of the tumour was resected at a different institution through a left posterior orbitotomy and medial canthopexy. The pathology specimen from that resection showed papillomatous light pink tumour fragments of inverted papilloma with numerous mucous cells. Re-excision of the sinonasal mass was performed via external-approach rhinotomy, left medial maxillectomy, left sphenoidectomy and ethmoidectomy. The specimen resected during this last surgical resection was reported as “low-grade mucoepidermoid carcinoma ex-inverted papilloma”. The patient underwent adjuvant radiotherapy and is well with no tumour recurrence 9 months after her last surgery. Gross examination showed papillary pink, tan, and white tissue fragments admixed with membranous mucosal and bone fragments. Microscopic examination showed the lesion consisting predominantly of a thickened, multilayered non-keratinizing squamous epithelium replacing normal respiratory mucosa, and seromucous glands and ducts. The neoplastic cells showed an inverted or endophytic growth pattern extending into the underlying stroma consistent with inverted Schneiderian papilloma (Figure 2a); however, admixed with the squamous epithelium were a large number of mucous and goblet cells (Figure 2b), more than would be expected in an inverted papilloma. Additionally, multiple foci of cytologic atypia, nuclear pleomorphism (Figure 2c) and invasion of the bone were noted (Figure 2d). These microscopic findings, taken together with the aggressive nature of the tumour and its high rate of growth, caused the
Mucoepidermoid carcinoma (MEC) typically arises from major salivary glands, minor salivary glands of the oral cavity and mucous glands of the aerodigestive tract. Cases of MEC arising from benign sinonasal or lacrimal papillomas are extremely rare. Herein we describe a MEC representing malignant transformation of an inverted Schneiderian papilloma. The patient presented with nasal bridge pain radiating to the premaxillary regions. Imaging showed a tumour involving the left nasal cavity, left ethmoid and maxillary sinuses and extending into the left orbit and lacrimal sac. Initial biopsy and debulking specimens showed only inverted papilloma. The re-excision specimen demonstrated a tumour with features of both inverted papilloma and MEC that superficially invaded bone. The tumour was negative for MECT1-MAML2 translocation. Linear array analysis of tumour tissue demonstrated the presence of human papillomavirus-11 (HPV-11).
Keywords inverted Schneiderian papilloma; lacrimal system; mucoepidermoid carcinoma; sinonasal tract
Introduction Schneiderian mucosa lines most of the paranasal sinuses and the nasal cavity with the exception of the nasal vestibule and the roof of the nose, which are lined by stratified squamous epithelium and olfactory mucosa respectively. Three benign neoplastic papillomatous neoplasms arise from the Schneiderian membrane: exophytic (also referred to as fungiform or everted)
Martin D Hyrcza MD Resident, Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada. Conflicts of interest: none declared. Ralph W Gilbert MD FRCSC Professor, Department of OtolaryngologyHead and Neck Surgery/Surgical Oncology, Wharton Head and Neck Program, University Health Network, Princess Margaret Hospital, Toronto, Ontario, Canada. Conflicts of interest: none declared. Eugene Yu MD FRCPC Associate Professor, Joint Department of Medical Imaging of Mount Sinai Hospital and University Health Network and Department of Medical Imaging, University of Toronto, Ontario, Canada. Conflicts of interest: none declared. ~ez MD FRCPC Associate Professor, Department of Bayardo Perez-Ordon Pathology, University Health Network, and Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada. Conflicts of interest: none declared.
DIAGNOSTIC HISTOPATHOLOGY --:-
1
Ó 2015 Elsevier Ltd. All rights reserved.
Please cite this article in press as: Hyrcza MD, et al., Mucoepidermoid carcinoma ex-inverted papilloma, Diagnostic Histopathology (2015), http:// dx.doi.org/10.1016/j.mpdhp.2015.06.002
INSTRUCTIVE CASE
Figure 1 Axial and coronal T1 weighted post gadolinium enhanced images demonstrates mild enhancement of the left anterior ethmoid region mass that has extended into and is enlarging the nasolacrimal sac fossa.
classification of this tumour as a low grade mucoepidermoid carcinoma arising from an inverted Schneiderian papilloma (i.e. a low grade mucoepidermoid carcinoma ex-inverted Schneiderian papilloma).
Immunohistochemistry for p16 showed strong but heterogeneous staining in about 30% of the tumour cells (Figure 3a). Ki67 labeling index was approximately 20% (Figure 3b). HPV molecular testing by Linear Array demonstrated the presence of
Figure 2 Papillomatous area composed of non-keratinizing squamous epithelium with an endophytic grow pattern (a). Invasive carcinoma composed of atypical non-keratinizing squamous cells and numerous mucous goblet cells (b). Atypical squamous cells showing hyperchromatic and pleomorphic nuclei (c). Focus of mucoepidermoid carcinoma close to trabeculae of ethmoid bone (d).
DIAGNOSTIC HISTOPATHOLOGY --:-
2
Ó 2015 Elsevier Ltd. All rights reserved.
Please cite this article in press as: Hyrcza MD, et al., Mucoepidermoid carcinoma ex-inverted papilloma, Diagnostic Histopathology (2015), http:// dx.doi.org/10.1016/j.mpdhp.2015.06.002
INSTRUCTIVE CASE
Figure 3 Diffuse expression of p16 in the tumour cells (a). MIB-1 proliferative index of approximately 20% (b).
transformation of the background papilloma, this is not likely with a low grade mucoepidermoid carcinoma whose squamous component can merge seamlessly with the background papilloma. The diagnosis, as in our case, rests on the clinically demonstrated aggressive growth combined with microscopically demonstrated bony invasion, cytologic atypia, and typical mucoepidermoid architecture and cytology. Molecular testing for MECT1-MAML2 rearrangement can be performed if in doubt, although a negative result does not exclude the diagnosis as only w50e66 % of MECs harbor the translocation.6 The presence of HPV11 in inverted papillomas has been described previously, with a reported prevalence of 30%.7 It is likely then that the inverted papilloma in which the MEC arose already carried the infection. However, there is no evidence that the virus is associated with malignant transformation. The low risk HPVs such as HPV11 do not inactivate the Rb protein, which regulates p16 protein expression. Thus, tissues infected with HPV11 tend to show weak and patchy p16 staining. The strong but patchy p16 expression in this tumour is therefore likely a result of the molecular changes occurring during the malignant transformation and unrelated to the presence of HPV11. In the study of 20 carcinomas ex-Schneiderian papillomas, Nudell et al. report 3 cases showing strong positivity in 20e40% of cells and an additional 5 cases with strong, diffuse positivity in >70% of cells. Only 3 of these 8 cases were HPV ISH positive.2 A
HPV-11 DNA in the tumour. The tumour was tested for MAML2 rearrangements by split-apart fluorescence in-situ hybridization (FISH) which was negative.
Discussion Mucoepidermoid carcinoma (MEC) most commonly arises in major salivary glands and minor salivary glands of the oral cavity and the respiratory tract. It is also known to occasionally arise from the major and minor lacrimal glands of the orbit and in the nasolacrimal system. Finding of mucoepidermoid carcinoma arising from a Schneiderian papilloma is rare. In his recent examination of 20 cases of carcinomas arising in Schneiderian papillomas, Nudell et al. reported two cases of MEC, both high grade.2 The majority of the other 18 cases involved squamous cell carcinomas. Kapadia et al. reported two cases of MEC arising from oncocytic (cylindrical cell) Schneiderian papilloma out of six cases of malignant transformation in this type of the tumour found in the Armed Forces Institute of Pathology archives.4 Our review of literature revealed another case of mucoepidermoid carcinoma arising from previously resected squamous papilloma of the lacrimal sac,5 bringing the total of published cases of this entity to five. The diagnosis of low-grade mucoepidermoid carcinoma exSchneiderian papilloma may be a challenge for several reasons. First, inverted papillomas are known to contain mucous and goblet cells individually or forming small clusters1 thus their presence alone is not sufficient to suspect transformation to MEC. In our case the mucous cells were present extensively throughout the lesion and not just focally. Second, inverted papillomas, despite being benign neoplasms, sometimes behave locally aggressive with extension into local structures such as the sinuses, the nasolacrimal system and the orbit, as seen in this case. Thus, aggressive behaviour alone is not sufficient to suspect malignant transformation, although it should prompt a careful search for other atypical features. Third, minor foci of cytologic atypia can be observed in Schneiderian papillomas, especially in areas of inflammation, and are typically without any clinical significance. An additional difficulty involves the low grade of the carcinoma, whereas large areas of high grade MEC would likely stand out and be relatively easily diagnosed as
DIAGNOSTIC HISTOPATHOLOGY --:-
REFERENCES ~ez B. Hamartomas, papillomas and adenocarcinomas of 1 Perez-Ordon the sinonasal tract and nasopharynx. J Clin Pathol 2009; 62: 1085e95. 2 Nudell J, Chiosea S, Thompson LDR. Carcinoma ex-Schneiderian papilloma (malignant transformation): a clinicopathologic and immunophenotypic study of 20 cases combined with a comprehensive review of the literature. Head Neck Pathol 2014; 8: 269e86. 3 Wolfish EB, Nelson BL, Thompson LDR. Sinonasal tract mucoepidermoid carcinoma: a clinicopathological and immunophenotypic study of 19 cases combined with a comprehensive review of the literature. Head Neck Pathol 2012; 6: 191e207.
3
Ó 2015 Elsevier Ltd. All rights reserved.
Please cite this article in press as: Hyrcza MD, et al., Mucoepidermoid carcinoma ex-inverted papilloma, Diagnostic Histopathology (2015), http:// dx.doi.org/10.1016/j.mpdhp.2015.06.002
INSTRUCTIVE CASE
4 Kapadia SB, Barnes L, Pelzman K, Mirani N, Heffner DK, Bedetti C. Carcinoma ex oncocytic Schneiderian (cylindrical cell) papilloma. Am J Otolaryngol 1993; 14: 332e8. 5 Lee SB, Kim KN, Lee SR, Bernardino CR. Mucoepidermoid carcinoma of the lacrimal sac after dacryocystectomy for squamous papilloma. Ophthal Plast Reconstr Surg 2011; 27: e44e6. 6 Seethala RR, Dacic S, Cieply K, Kelly LM, Nikiforova MN. A reappraisal of the MECT1/MAML2 translocation in salivary mucoepidermoid carcinomas. Am J Surg Pathol 2010; 34: 1106e21. 7 Shen J, Tate JE, Crum CP, Goodman ML. Prevalence of human papillomaviruses (HPV) in benign and malignant tumors of the upper respiratory tract. Mod Pathol 1996; 9: 15e20.
Practice points C
C
C
DIAGNOSTIC HISTOPATHOLOGY --:-
4
Malignant transformation of inverted Schneiderian papillomas is a well recognized complication therefore proper sampling and careful examination of these lesions is necessary to avoid delays in their pathologic diagnosis The most common carcinoma arising in inverted Schneiderian papillomas are squamous cell carcinoma; however, rare examples of mucoepidermoid carcinoma, sinonasal type undifferentiated carcinoma and high-grade neuroendocrine carcinoma (small celltype) have also been described The molecular mechanisms, including the role played by HPV, underpinning the malignant transformation of inverted Schneiderian papilloma are not known
Ó 2015 Elsevier Ltd. All rights reserved.
Please cite this article in press as: Hyrcza MD, et al., Mucoepidermoid carcinoma ex-inverted papilloma, Diagnostic Histopathology (2015), http:// dx.doi.org/10.1016/j.mpdhp.2015.06.002