CT features and pathologic characteristics of lymphoepithelial carcinoma of salivary glands

Objective: To investigate and analyze the typical CT findings of salivary gland lymphoepithelial carcinoma. Methods: CT findings in 8 patients with lymphoepithelial carcinoma (LEC) in salivary gland were studied retrospectively. Surgical resection was performed in all cases. Results: 8 cases were subdivided to primary tumor and secondary tumor. In primary tumor group, 5 were localized in the parotid gland, 2 were found in the submandibular glands; 6 lesions had with homogeneous density, 1 was associated with cystic degeneration and 1 with calcification; the margins of lesions in 5 cases were poorly defined, while well-defined in 2. On enhanced CT: obvious enhancement was achieved in all of the 7 solitary lesions, among which 4 were homogenously enhanced while the other 3 had heterogeneous enhancement. In the 2 cases of nodules in deep lobe, retromandibular vein was affected; 7 patients had positive Epstein-Barr virus (EBV) test, with Ki-67 measurements ranged from 40% to 80%. 1 patient had LEC secondary to Benign Lymphoepithelial Lesion (BLEL), with involvement of bilateral parotid glands; the lesion was manifested as multiple differently-sized nodules, with partial cystic change, all of the nodules had clear margins, and obvious ring-shape enhancement was seen in the nodules with cystic change; the patient with secondary LEC had negative EBV test and a Ki-67 value of 20%. Conclusion: In most cases, LEC was primary and occurred in the parotid glands. The probable diagnosis could be made based upon Dual-phase contrast-enhanced CT scan findings combined with positive expression of EBV.     

Hemangioma of the salivary gland: a study of ten cases of a rarely biopsied/excised lesion

Hemangioma is a common soft tissue tumor that frequently occurs in the oral and maxillofacial region including salivary glands, but is rarely biopsied and is therefore often unfamiliar to the surgical pathologist. Our study examined the subclassification and histologic features of salivary gland hemangioma (SGH). Consultative cases coded as hemangioma and located in salivary gland from 1970 to 2000 were retrieved from the Registry of Oral and Maxillofacial Pathology of the Armed Forces Institute of Pathology (Washington, DC). Only cases with histologic evidence of salivary gland involvement were included. Slide material and patient history for all cases were reviewed, subclassification assigned, and histologic features were noted. Ten cases coded as hemangioma with slides and history met our inclusion criteria. Seven cases were the "juvenile hemangioma" subtype in the parotid of infants, ranging in age from 3 to 10 months (mean age, 5.3 months) with a male predominance. These SGH had a distinctive histologic appearance of a cellular proliferation of capillary sized vessels around retained salivary gland ducts. Mitoses were easily identified. Three additional cases in females included an arteriovenous hemangioma of a lip minor salivary gland since birth in a 15-month-old infant and two parotid gland lesions: a lobular capillary hemangioma of a 10-year-old and a cavernous hemangioma in a 51-year-old. The latter three cases grew as replacing masses and lacked retained salivary gland ducts within the lesion, despite glandular tissue at the periphery of the tumor. No SGH cases in our series were identified in the submandibular or sublingual glands. Despite its common occurrence, SGH is relatively rare in our surgical pathology files. The parotid gland is the most common location (90%). Salivary gland hemangioma includes usual hemangioma subtypes, mainly in females, and a distinctive infantile subtype of capillary hemangioma (juvenile hemangioma), displaying distinctive histology and found predominately in males. The cellularity, mitotic activity, and retained salivary gland ducts in the latter lesion should not make one consider malignancy.     

Peripheral T-cell lymphoma arising from an intraglandular lymph node in the parotid gland: a case report and literature review

T/NK-cell lymphoma of the salivary gland is rare. A 58-year-old man complained of a tumor mass in the left parotid gland region and he was diagnosed to have a left parotid tumor. The tumor was subsequently resected, revealing a diffuse growth pattern of medium to large sized atypical cells. The tumor was surrounded by fibrous connective tissue in the form of a capsule, and those were positive for CD3, CD4, CD5 and CD30, but negative for Bcl2, CD8, CD10, CD15, CD20, CD25, CD56, CD79a, CD246, EMA, granzyme B, TdT and TIA-1. There was no molecular evidence of Epstein-Barr virus (EBV) infection. It was diagnosed as peripheral T-cell lymphoma (PTCL) arising from an intraglandular lymph node in the parotid gland. In conclusion, Only 17 cases of primary T/NK-cell lymphoma of the salivary glands have been recorded until now, and the characteristics of these are not clear yet. Additional study is needed.     

腮腺淋巴上皮瘤样癌与EB病毒感染的关系

目的：研究ＥｐｓｔｅｉｎＢａｒｒ 病毒（ＥＢＶ）与腮腺淋巴上皮瘤样癌（ｌｙｍｐｈｏｅｐｉｔｈｅｌｉｏｍａｌｉｋｅｃａｒｃｉｎｏｍａ,ＬＥＬＣ）的关系,并检测瘤细胞内ＥＢＶ 基因编码产物。方法：作者收集了中山医科大学所属病理科１９８６ 年１ 月至１９９５ 年１２ 月间３２ 例腮腺ＬＥＬＣｓ．。３２ 例ＬＥＬＣ石蜡包埋标本再次切片。采用免疫组化和原位核酸杂交法检测瘤细胞内ＥＢＶ 基因表达产物。结果：（１） 在１２５例腮腺癌中有３２ 例淋巴上皮瘤样癌,占总病例的２５－６％ （３２／１２５） 。（２）所有３２ 例腮腺ＬＥＬＣ组织中均有数量不等的ＥＢＮＡ１ 和ＥＢＥＲｓ 阳性瘤细胞。（３）２７ 例ＬＥＬＣ 组织中部分瘤细胞表达ＬＭＰ１ 。（４） 所有标本中均未见ＺＥＢＲＡ 阳性细胞。（５）３２例腮腺ＬＥＬＣ组织中ＥＡＤ、ＶＣＡ和ＭＡ的阳性表达率分别为７１－９ ％（２３／３２） 、６８－８ ％（２２／３２） 和１２－５％ （４／３２） 。结论：（１） 在鼻咽癌高发的广州地区,腮腺ＬＥＬＣ的发病率也较高。（２）腮腺ＬＥＬＣ 组织中均有ＥＢ病毒感染。（３）ＥＢ病毒在腮腺ＬＥＬＣ的感染主要为潜伏Ⅱ型,即表达ＥＢＮＡ１ 、ＥＢＥＲｓ 和ＬＭＰ１     

Ultrastructure of sialadenoma papilliferum

Sialadenoma papilliferum is a rare tumor of salivary gland origin and has been reported in the parotid and minor salivary glands of the oral cavity. This tumor is morphologically similar to the papillary syringoadenoma of the sweat gland. We report the clinical and morphologic features of five cases and review the literature. Ultrastructural examination of case 1 revealed the predominant cell type to be an oncocytic cell. These cells contained numerous mitochondria, exhibited parallel filaments within the cell cytoplasm, and were attached by desmosomes. The neoplastic cells appear to exhibit characteristic features of various cell types of the salivary gland duct apparatus.     

Primary T cell lymphoma of salivary gland: a report of a case and review of the literature

Lymphoma of the salivary gland accounts for 5% of cases of extranodal lymphoma and 10% of malignant salivary gland tumours. Most primary salivary gland lymphomas are B marginal zone lymphomas arising on a background of sialadenitis associated with autoimmune disorders such as Sjorgen's syndrome. Primary T cell lymphoma of the salivary gland is rare. This report describes a case of primary T cell lymphoma arising in the parotid gland of an elderly white man, which was notable for its striking resemblance to a B cell extranodal marginal zone lymphoma. Immunohistochemistry and gene rearrangement studies confirmed the clonal T cell nature of the tumour. There was no molecular evidence of Epstein-Barr virus (EBV) infection of neoplastic or surroundings cells. Only 14 cases of primary T cell lymphoma of the salivary glands have been recorded in the literature, most being from the Orient and having extremely variable prognosis. Those with a T/natural killer cell phenotype are associated with EBV infection. This case highlights the fact that T cell lymphoma in the salivary gland can mimic closely the morphological features of B cell extranodal marginal zone lymphoma.     

Ultrastructural and Immunohistochemical Study of Salivary Duct Carcinoma of the Parotid Gland

A case of salivary duct carcinoma of the parotid gland found in an 81-year-old man was studied by light microscopy, immunohistochemistry, and electron microscopy. Histologically, the tumor was composed of elongated cords of cells and ductal structure with desmoplastic stromal reaction. Tumor cell nests sometimes showed central comedonecrosis. Immuno-histochemically, the tumor cells were positive for cytokeratin and epithelial membrane antigen, and they were negative for S-100 protein and muscle-specific actin. Electromicroscopi-cally, two cell types were identified. The first cell type showed electron-lucent cytoplasm with scant organelles. The second type cell contained numerous mitochondria. Neither acinar nor myoepithelial cell differentiation was observed. These findings suggest that salivary duct carcinoma originates from the interlobular or excretory ducts.     

Dedifferentiated malignant myoepithelioma of the parotid gland

Dedifferentiated salivary gland tumor is a rare, recently recognized tumor type. A case of dedifferentiated malignant myoepithelioma in a 59-year-old man who presented with a painful mass in the left preauricular region is reported. Histologically, two distinct neoplastic cell populations were observed in the same tumor mass. The first population was composed of solid nests of polygonal eosinophilic or glycogen-rich clear cells showing neoplastic myoepithelial immunocytological features, such as positivity for cytokeratins, vimentin, S-100 protein (S-100), alpha-smooth muscle actin (SMA) and glial fibrillary acidic protein (GFAP). A multinodular growth pattern, necrosis and occasional mitotic figures suggested malignancy. This population was diagnosed as low-grade malignant myoepithelioma. The second population infiltrated diffusely into the parotid gland and facial nerves. It consisted of polygonal or short spindle cells with obvious pleomorphism and atypical mitoses. The tumor cells were positive for vimentin and cytokeratins, and showed an accumulation of p53 and cyclin D1. S-100 protein, SMA and GFAP were negative. This population was regarded as undifferentiated carcinoma. A final diagnosis of dedifferentiated malignant myoepithelioma was made. This seems to be the first published case of dedifferentiation in malignant myoepithelioma. Because any tumor type can undergo dedifferentiation with accumulation of additional genetic changes, complete sampling should be the standard approach to all salivary gland tumors in order to avoid missing a dedifferentiation component.     

Intraductal papillary tumors of the major salivary glands: case reports of benign and malignant variants

Intraductal papilloma is an extremely rare benign salivary gland tumor that occurs most commonly in the minor salivary glands. To our knowledge, a malignant counterpart of intraductal papilloma has not been described previously. We report one case each of benign and malignant intraductal papillary tumors. The benign tumor occurred in the sublingual gland and was a typical example of intraductal papilloma, with the exception that we found no previously published reports of this type of tumor in this location. The other patient had a left parotid gland tumor that was architecturally similar to the intraductal papilloma, with the addition of cytologic atypia, intraductal extension, microinvasion, and lymph node metastases. This tumor was diagnosed as intraductal papillary adenocarcinoma with an invasive component. Both patients were alive and well without evidence of recurrence 2 years and 6 months (case 1) and 6 years (case 2) after surgery. Immunohistochemical examination revealed that the tumor cells resembled duct luminal cells in both cases. The 2 tumors had different immunoreactivities for carcinoembryonic antigen, p53, and Ki-67. The malignant counterpart of intraductal papilloma should be considered in the differential diagnosis of salivary gland tumors with a predominantly papillary structure, even though this tumor is extremely rare.     

Lymphoepithelial carcinoma of the salivary gland: in situ detection of Epstein-Barr virus.

AIM--To examine the role of Epstein-Barr virus (EBV) in lymphoepithelial carcinoma of the salivary gland in Hong Kong Chinese. METHODS--Ten cases of lymphoepithelial carcinoma of the salivary gland (eight parotid and two submandibular) were examined. In situ hybridisation was used to localise EBER RNA, immunohistochemical methods to detect expression of latent membrane protein 1 (LMP-1) in EBV positive tumours, and Southern blot analysis to examine the clonality of EBV in the two cases where frozen tissue was available. RESULTS--None of the cases had a history of Sjögren's syndrome or histological evidence of a benign lymphoepithelial lesion. The IgA antibody titre against EBV viral capsid antigen was elevated in four cases. All cases were EBV positive by in situ hybridisation, with a strong uniform positive signal in the epithelial cells, and all cases expressed LMP-1. Southern blot analysis revealed that the clonal episomal form of the virus was present. Two of the three female patients in this series also developed carcinoma of cervix. One of these carcinomas had histological features of a lymphoepithelioma-like carcinoma but was EBV negative. CONCLUSIONS--A consistent association between EBV and lymphoepithelial carcinoma of the salivary gland was found. The presence of the virus in a clonal episomal form, and the expression of LMP-1 viral oncoprotein is further evidence of the role of EBV in the oncogenesis of this tumour.     

The detection of Epstein-Barr virus in the lesions of salivary glands.

Epstein-Barr virus (EBV) is known in association with lymphoid and epithelial lesion. Because the salivary gland is an organ close to the oropharynx, it has a higher incidence of EBV infection and is a possible route of EBV infection. Formalin-fixed, paraffin embedded tissue sections of 87 cases of salivary gland diseases were used for the study of EBV with PCR, in situ PCR for EBNA-1 (EBV nuclear antigen-1), and immunohistochemistry for LMP-1 (latent membrane protein-1). EBV was detected in 12 cases (13.8%): 7 of nonspecific chronic sialadenitis (21.2%), 4 of Warthin's tumors (30.8%), and one lymphoepithelial carcinoma. EBNA-1 was negative in all the other lesions. EBV DNA was detected in the nucleus of epithelial cells and the surrounding lymphocytes. LMP-1 positivity was found in the cytoplasm of epithelial cells. The results of the present study showed that EBV is implicated in some of the inflammatory and neoplastic lesions of the salivary gland in which the lymphocytes are abundant. However, the pathogenesis and mechanism of immortalization and tumorigenesis of the epithelial cells in the salivary glands remain to be determined.     

Mammary analog secretory carcinoma of salivary gland with high-grade histology arising in hard palate,report of a case and review of literature

Mammary gland analog secretary carcinoma (MASC) of salivary gland is typically a tumor of low histologic grade and behaves as a low-grade malignancy with relatively benign course. This tumor shares histologic features, immunohistochemical profile, and a highly specific genetic translocation, ETV6-NTRK3, with secretory carcinoma of breast. Histologically, it is often mistaken as acinic cell carcinoma, adenocarcinoma not otherwise specified, and other primary salivary gland tumors. Here we report a case of MASC with high-grade transformation and cervical lymph node metastases confirmed with ETV6-NTRK3 translocation arising in the hard palate of a 41 year-old adult. Interestingly, the metastatic carcinoma has lower grade than the original tumor which strongly support malignant transformation of the original tumor. Most commonly, MASC arises from the parotid gland and less often in minor salivary glands. Metastasis is relatively uncommon and high-grade histology has only been reported in four cases with three of them arising from the parotid gland and the location of the fourth one has not been reported. This is the first case with high grade histology that arise from minor salivary gland and it emphasizes the importance of molecular screening of salivary gland tumor with high-grade histology for ETV6-NTRK3 translocation. In our literature of 115 cases that includes the current case, MASC occurred predominantly in adult with only a few cases under 18 years of age and a male to female ratio of 1.2:1. Parotid gland is more commonly affected but there is also significant occurrence in minor salivary glands. Except for the cases with high grade histology, the overall prognosis is good.     

Sebaceous carcinoma of the parotid gland

Summary Sebaceous carcinoma of salivary gland origin is extremely rare and, because of its rarity, the clinicopathological characteristics and the histogenesis are not fully understood. We present a case of sebaceous carcinoma of the parotid gland which brings the total number of reported cases to 22.The tumor showed epithelial cell nests which were mainly composed of sebaceous cells with marked cellular atypia. In most of the nests, glandular spaces lined by ductal epithelium were present. Scattered mucous cells and flattened eosinophilic cells at the periphery of the nests were also seen. Ultrastructural and immunohistochemical observations of the tumour revealed coexistence of sebaceous and glandular differentiations in some tumour cells. Tumour cells with lipid granules often participated in the formation of glandular structures or exhibited intracytoplasmic lumina, and immunohistochemical localization of lactoferrin and secretory component, the functional markers of ductal epithelium of salivary gland, was demonstrated not only in duct-forming tumour cells but also in many sebaceous tumour cells.It seems likely that sebaceous carcinoma originates from pluripotential duct cells which can differentiate into sebaceous, ductal and mucous cells.     

Undifferentiated carcinoma of the salivary gland in Greenlandic Eskimos: demonstration of Epstein-Barr virus DNA by in situ nucleic acid hybridization.

Paraffin sections of 11 undifferentiated salivary gland carcinomas of lymphoepithelioma type (malignant lymphoepithelial lesion) arising in Greenlandic Eskimos (Inuit) were examined for the presence of Epstein-Barr virus (EBV) using in situ nucleic acid hybridization with a 35S-labeled EBV-specific probe. Epstein-Barr virus genomes were detected in each case in malignant epithelial cells, but were not found in lymphoid stroma or in residual benign salivary epithelium. Eight undifferentiated salivary gland carcinomas from non-Eskimo patients (including two with lymphoepithelioma-like features) were negative for EBV-DNA. Our results confirm the existence of a consistent and specific association between EBV and tumor cells of undifferentiated salivary gland carcinoma of lymphoepithelioma type arising in Greenlandic Eskimos.     

Metastatic renal cell carcinoma,clear cell type,of the parotid gland

Renal cell carcinoma (RCC), clear cell type, is a commonly encountered metastatic tumor that can present at unusual anatomic sites many years after the primary tumor resection. Noncutaneous metastasis to the parotid gland is unusual; however, a number of cases of parotid RCC metastasis have been reported. Fine‐needle aspiration biopsy (FNAB) is regularly utilized during the evaluation of salivary gland lesions, where it has a high sensitivity, specificity, and accuracy; however, the identification and definitive diagnosis of primary and metastatic clear cell neoplasms is a potential diagnostic pitfall for salivary gland FNAB. Here, we describe a case of RCC, clear cell type, metastatic to the parotid gland that was diagnosed entirely from FNAB cell block material, which is the first such reported case to our knowledge. We review the literature for cases of parotid RCC metastasis and focus on the utility of FNAB for synchronous versus metachronous presentations. Finally, we evaluate the differential diagnosis of clear cell parotid lesions, including ancillary histologic studies, and propose an algorithmic approach to clear cell neoplasms of the salivary gland. Diagn. Cytopathol. 2014;42:974–983. © 2014 Wiley Periodicals, Inc.     

Synchronous benign epithelial tumors arising in the palatal minor salivary gland. First report of an unusual minor salivary gland lesion

A review of the literature shows that unilateral benign salivary gland tumors of different histologic types in a single gland are so rare as to be curiosities, and all of such reported tumors have arisen in the parotid gland. The present paper reports a case of synchronous benign epithelial tumors of different histologic type arising in the palatal minor salivary gland of a 57-year-old woman who had first noted palatal swelling about 20 years previously. Pathologically, the lesion was composed of two distinct tumors, pleomorphic adenoma and lumenless trabecular adenoma, which were sharply demarcated from each other by a thin layer of fibrous connective tissue. Foci of tumor cells with cellular atypia were seen in some areas of the pleomorphic adenoma. The present case is thought to represent a previously undescribed component within the spectrum of minor salivary gland tumors.     

Sialolipoma: a report of seven cases of a new variant of salivary gland lipoma

AIMS: We propose the designation 'sialolipoma' to establish and characterize a new category of benign lipomatous tumour occurring in salivary glands. Until now, these tumours have not been regarded as a distinct entity in the salivary glands. METHODS and RESULTS: We evaluated the clinicopathological and immunohistochemical features of seven sialolipomas among 2051 surgically resected primary salivary gland tumours deposited in our files. The seven patients with sialolipoma were five men and two women, aged 20-75 years (mean: 54.4 years). Five tumours had arisen in the parotid gland, one in the soft palate, and one in the hard palate. The tumours ranged from 10 to 60 mm (mean: 38 mm) in maximum diameter. Histologically, the tumours were characterized by a well circumscribed mass composed of glandular tissue and mature adipose elements. The adipose elements in the tumours arising in the parotid gland were more abundant than those arising in the minor salivary gland. The glandular components consisted of ductal, acinar, basal and myoepithelial cells, and closely resembled the cellular and structural compositions of normal salivary gland tissues. These findings were confirmed by immunohistochemical and ultrastructural studies. These components had no atypia, except for the presence of some minor variations, e.g. ductal ectasia with fibrosis and focal oncocytic metaplasia. In all cases, cell proliferative activity, as assessed by Ki67 (MIB1) immunostaining, was low. From these findings, it is likely that our cases were lipomas with secondary entrapment of the salivary gland elements. No recurrence was seen in all cases after superficial parotidectomy, or after surgical excision in the patients with palatal tumours. CONCLUSIONS: We regard sialolipoma as a distinct variant of salivary gland lipoma that can occur in both the major and minor salivary glands. Superficial parotidectomy, or surgical resection in the case of palatal tumours, is an appropriate treatment for this benign tumour.     

Salivary gland tumors in Uganda: clinical pathological study

Background

The incidence of salivary gland tumors is claimed to be influenced by geographical and racial factors. The pathological classification and nomenclature of salivary gland tumors as defined by WHO classification (1991), is accepted world-wide but little is available in the literature regarding the spectrum of salivary gland tumors in Africa in the basis of this classification. Such efforts would allow comparison and justify any differences between the black African population and the rest of the world.

Objective

To outline the clinicopathological features of salivary gland tumors in Uganda.

Setting

Makerere University, Faculty of Medicine, Department of Pathology.

Methods

All epithelial tumors from major and minor salivary glands accessioned from 1979 to 1988 were analyzed in respect to sex and age of patients, anatomical location of the tumor and histological type. The histological diagnosis of each individual tumor was based on the 1991 WHO classification of salivary gland tumors.

Results

During the span of 10 years, 268 cases of salivary gland tumors were diagnosed. Of these, 113 (42.2%) were males, 148 (55.2%) females and in the remaining seven (2.6%) cases, the sex was not specified. The age range of the 247 patients with recorded ages was from 0.5 to 80 years. The mean age at diagnosis was 38.1 (SD =17.03) with the median of 38.0 years. Thirty four percent of tumors originated from the parotid, 33.2% from the submandibular and 32.8% from minor salivary glands. No tumor was implicated from the sublingual gland. There were a total of 125 (46.6%) malignant tumors and 143 (53.4%) benign tumors. The mean age of patients with malignant lesions (43.1 years; SD=16.75; median=44.00 years) was 9.6 years older than those with benign tumors (mean=33.5 years; SD=16.0; median=30.00 years). Pleomorphic adenoma was the most common benign tumor (74.8%), followed by myoepithelioma (9.8%). No Whartin''s tumor was encountered. The malignant tumors were dominated by adenoid cystic carcinoma (28.8%) followed by mucoepidermoid carcinoma (21.6%).

Conclusion

The pattern of distribution of salivary gland tumors in black African population seems to differ from that of Western series in that; i) females are more affected than males, ii) there is a low proportion of tumors from the parotid gland and high proportion of tumors from the submandibular and minor salivary glands, iii) the parotid and minor salivary gland tumors have more probability of being malignant than those tumors from the submandibular gland iv) the newly categorized pathological entities are common and v) Whartin''s tumor is extremely rare in black African population.     

Salivary gland monomorphic adenoma. Ultrastructural,immunoperoxidase, and histogenetic aspects.

Monomorphic adenoma of basal cell type is a salivary gland tumor believed to result from a proliferation of a single type of cell. However, ultrastructural and immunocytochemical investigations of 6 monomorphic adenomas (5 from parotid and 1 from intraoral minor salivary gland) indicate that there are two classes of these lesions, one composed of two types of tumor cells and the other wholly or predominantly made up of one type of cell (isomorphic). In the former group, the organization of the tumor cells closely mimicked that of normal and hyperplastic salivary gland intercalated ducts. Aggregates of tumor cells were arranged as an inner layer of luminal epithelial cells which were surrounded by an outer layer of cells that, in some cases, had ultrastructural and immunohistochemical features indicating myoepithelial cell differentiation. In some adenomas formed by two types of tumor cells, basal-lamina-lined extracellular spaces were identified ultrastructurally in relation to modified myoepithelial cells; such spaces had the same fine-structural features as those reported in pleomorphic adenoma and adenoid cystic carcinoma. Predominantly isomorphic adenomas were composed exclusively of luminal epithelial cells. These results indicate that despite the varied histologic patterns in the numerous subtypes of monomorphic adenoma, there is a central theme of differentiation and organization in this type of neoplasm which recapitulates the ductoacinar unit of normal salivary gland parenchyma.     

High‐grade epithelial‐myoepithelial carcinoma of the parotid gland with mucous cell differentiation

Epithelial‐myoepithelial carcinoma (EMC) is a rare salivary gland tumor with a low‐grade malignancy, and EMC with high‐grade histopathological features is exceedingly rare. Furthermore, EMC with intracellular mucin is also extremely rare. We report an uncommon case of a high‐grade EMC of the parotid gland with mucous cell differentiation in a 66‐year old Japanese woman who noticed a right palpable parotid mass increasing in size within a one‐year period. The cytological specimen showed a focally biphasic structure and included isolated or discohesive piled‐up clusters with hyaline globules surrounded by neoplastic cells with nuclear atypia. The gross examination revealed a relatively well‐demarcated, multinodular gray‐whitish and solid mass. Histologically, the tumor consisted of variably sized solid nests or trabeculae with central necrosis and increased mitotic activity, and invaded into adjacent skeletal muscles. Immunohistochemically, the biphasic ductal and myoepithelial differentiation of this tumor confirmed the diagnosis of high‐grade EMC. Furthermore, numerous small nests with d‐PAS and alcian blue‐positive mucous cells predominated in about 5% of the whole tumor, and these mucous cells were encompassed by neoplastic myoepithelial cells. We should recognize this variant of EMC because we can't rule out the possibility of EMC even in the presence of mucous cells.