Myoepithelial carcinoma of the parotid gland with a novel CTCF::NCOA2 fusion.

We describe a case of a myoepithelial carcinoma of the superficial parotid gland in a 46-year-old male harboring a novel CTCF::NCOA2 gene fusion. To our knowledge, this novel gene fusion has not been described previously in myoepithelial carcinoma. A 46-year-old male patient presented with a mass involving the superficial left parotid gland with extension into the external auditory canal (EAC) and erosion of the conchal cartilage. Histologically, the neoplasm was composed of uniform spindled, epithelioid/ovoid cells arranged in cords and nests within hyalinized to myxoid stroma. On immunohistochemistry (IHC), the tumor cells demonstrated patchy and variable staining for low molecular weight cytokeratin (CAM5.2), pan-cytokeratin (OSCAR), and S-100. Overall, the morphological and immunohistochemical attributes supported a locally aggressive tumor of myoepithelial differentiation consistent with myoepithelial carcinoma. Molecular analysis using a custom 115-gene gene panel by targeted RNA sequencing, showed an in-frame CTCF::NCOA2 fusion. In addition to reporting this novel fusion in myoepithelial carcinoma, we also discuss relevant differential diagnosis, and provide a brief review of NCOA2 gene function in both normal and neoplastic contexts.

Carcinoma showing thymus-like differentiation (CASTLE) of the salivary gland: Report of 2 cases of a hitherto under-recognized extrathyroid counterpart.

Carcinoma showing thymus-like differentiation (CASTLE) outside the thyroid gland is extremely rare. Here we report two cases of CASTLE of the major salivary gland. The tumors occurred in the parotid gland of a 31-year-old female (Case 1) and in the submandibular gland of a 40-year-old female (Case 2). Both tumors showed a lobulated growth pattern, and were histologically composed of a nested or sheet-like proliferation of carcinoma cells with round- to oval-shaped nuclei, distinct nucleoli and pale eosinophilic cytoplasm, accompanied by various degrees of lymphocytic infiltration. Immunohistochemical staining revealed that the tumors were positive for pan-cytokeratin, p40, CD5, CD117 and bcl-2. In addition, PD-L1 expression was seen in 10-90% of tumor cells. After the initial surgery, Case 1 remained tumor-free for 20 months, while Case 2 suffered lymph node recurrence at 4 months, followed by lung metastasis, which was treated with chemoradiotherapy and anti-PD-1 immune checkpoint inhibitor, resulting in a partial response. The present findings indicate that an extrathyroid counterpart of CASTLE can occur as a primary salivary gland neoplasm. Salivary CASTLEs seem to show a wide range of biological behavior, and long-term follow-up may be needed. Immune checkpoint inhibitor targeting PD-1 might become a promising treatment option in patients with CASTLE; however, further study with a larger number of cases is necessary to establish the optimal therapeutic strategy and prognostic factors for this rare cancer.

Follicular dendritic cell sarcoma of the parotid gland: A case report.

Follicular dendritic cell sarcoma (FDCS) is an exceedingly rare malignant neoplasm. The management of this tumor is fully challenging due to its rarity and lack of documentations. We share a case with primary parotid FDCS. This case report depicts the clinicopathological features of FDCS, which intends to serve as a reference to clinicians in its correct identification.

Epithelioid hemangioendothelioma of the parotid gland: A case report in an unusual location with a review of the literature.

Epithelioid hemangioendothelioma (EHE) is a malignant vascular tumor that usually affects the liver, lung, bone and deep soft tissues of the extremities or trunk. To our knowledge, only 3 cases in the parotid gland have been reported to date. We report a case of a 62-year-old woman who presented with a 1-year history of a slow-growing, painless mass over the left mandibular angle. Imaging studies showed a 2cm mass over the left parotid gland with peripheral calcifications. The patient underwent a superficial parotidectomy. Sections displayed neoplastic epithelioid cells with cytoplasmic vacuoles containing erythrocytes, surrounded by a myxohyaline stroma. Immunohistochemistry was positive for CD31, CD34, ERG, and factor VIII, but negative for cytokeratin AE1/AE3, CK7, EMA, SMA, and S100. The findings were those of an EHE involving the parotid gland. This case demonstrates an EHE in a rare location and emphasizes the need to consider this tumor when diagnosing uncommon soft tissue tumors of salivary glands.

Warthin-like Mucoepidermoid Carcinoma of the Parotid Gland: Unusual Morphology and Diagnostic Pitfalls.

BACKGROUND: Warthin-like mucoepidermoid carcinoma is a newly recognized rare entity and could be misdiagnosed as a benign Warthin tumor. We report such a case of a 36-year-old male who presented with a left parotid gland mass. CASE REPORT: Fine-needle aspiration showed features suggestive of Warthin tumor. Following parotidectomy, grossly there was a 1.6 cm well-circumscribed multilobular mass with focal areas of cystic change. Microscopically, at low magnification it had histological features resembling Warthin tumor, while lining with squamoid cells with scattered mucocytes demonstrating mild cytologic atypia was observed at high magnification. Immunohistochemically, the tumor cells were positive for p40, p63, cytokeratin 5/6, cytokeratin 7, and cancer antigen 125, but negative for discovered on GIST-1 (DOG1). Mucicarmine stain highlighted intracellular mucin within mucocytes. Rearrangement of mastermind like transcriptional coactivator 2 (MAML2) (11q21) gene was shown to be present in tumor cells by fluorescence in situ hybridization, supporting the diagnosis of a low-grade Warthin-like mucoepidermoid carcinoma. The patient was disease-free 12 months after surgery. CONCLUSION: Warthin-like mucoepidermoid carcinoma has not been widely recognized and can be misdiagnosed as Warthin tumor. Testing for MAML2 rearrangement provides essential support for diagnosis in difficult cases.

[Clinicopathologic and molecular features of myoepithelial tumors of salivary glands].

Objective: To investigate the clinicopathological, and molecular characteristics of myoepithelial tumors (MTs) of salivary glands. Methods: A total of 37 MTs cases including 13 malignant epithelial tumors (MMTs) and 24 benign epithelial tumors (BMTs) of salivary glands were identified from the archives of the Department of Pathology, General Hospital of Eastern Theater Command, dating from 2006 to 2016. Clinical features, histological patterns, immunohistochemical characteristics and status of EWSR1 gene rearrangement by fluorescence in situ hybridization (FISH) analysis were reviewed in all cases. Results: Clinically, 37 MTs cases mainly occurred in the parotid glands, when most of the patients presented with painless masses. Of the 13 MMTs cases, male to female ratio was 7∶6, and the median age was 62 years old. Of the 24 BMTs cases, male to female ratio was 5∶7, and the median age was 54 years old. Immunohistochemically, 37 MTs cases were positive for CKpan, and at least one myoepithelial marker. Twenty six of 37 MTs cases were analyzable for the EWSR1 gene break by FISH. Based on the previous evaluation criterion, the EWSR1 translocation was detected in 4 cases of 11 MMTs, and 4 cases of 15 BMTs. According to the main histological composition of tumor cells, 4 EWSR1-positive MMTs covered 2 clear-cell cases and 2 epithelioid-cell cases, when 4 EWSR1-positive BMTs covered 2 clear-cell cases, 1 plasmacytoid-cell case, and 1 spindle-cell case. Conclusions: Males and females are affected equally. MTs express immunoreactivity for CKpan, and at least one myoepithelial marker. The EWSR1 rearrangement is present in a subset of MTs, with variable morphological characteristics, and has no statistical significance on clinical behavior.

Application of the Milan System for Risk Stratification and Its Comparison with a Previous Reporting System of Parotid Gland Cytopathology in a Tertiary Care Centre.

OBJECTIVE: To compare the recently proposed Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) with the four-tiered reporting system (FTRS) followed at our institute. METHODS: Parotid gland fine-needle aspirates reported over a period of 5 years were analysed. These aspirates had been placed into 4 categories according to the FTRS: unsatisfactory (UNS), no evidence of malignancy/negative (NEG), inconclusive for malignancy (INC), and diagnostic for malignancy/positive (POS). Aspirates with follow-up histopathology were then categorized according to the MSRSGC as follows: non-diagnostic, non-neoplastic, atypia of unde-termined significance (AUS), neoplasm, suspicious for malignancy, and malignant. The risk of malignancy (ROM) was calculated. RESULTS: A total of 893 parotid region aspirates were evaluated and histopathology was available for 190 cases (21%). ROM in MSRSGC groups, namely non-diagnostic, non-neoplastic, AUS, neoplasm, suspicious for malignant neoplasm, and malignant, was 44, 8, 0, 12, 81 and 100%, respectively. ROM in FTRS groups, namely UNS, NEG, INC, and POS, was 45, 13, 67 and 100%, respectively. CONCLUSIONS: MSRGC and FTRS are comparable with respect to the ROM across groups. Compared to FTRS, the further subcategorisation of the non-malignant group, the use of specific nomenclature, and the reproducibility of MSRGC provide proper risk stratification, thereby guiding better management and resulting in improved patient care.

Unicystic high-grade intraductal carcinoma of the parotid gland: cytological and histological description with clinic-pathologic review of the literature.

Intraductal carcinoma of the salivary glands is a rare, not well-characterized tumor. We reviewed the literature and report the first case of a high-grade unicystic intraductal carcinoma of the parotid. Formalin-fixed/paraffin-embedded blocks were sectioned and stained for hematoxylin and eosin and immunostains (CAM5.2, EMA, CK5, p53, p63, SMA, S100 protein, DOG1, mammaglobin, AR, ER, PR, Her-2, and Ki67). A 72-year-old man showed a painless nodule (2 cm) in the right parotid region. A 'tumor of uncertain malignant potential' (low grade) was diagnosed by fine-needle aspiration cytology (FNAC). Preoperative magnetic resonance imaging revealed a well-delimited, oval cyst without evidence of parenchymal invasion (T1-scans: homogeneously isointense with hypointense thin peripheral ring; T2-scans: strongly hyperintense). Histological examination confirmed a unilocular cyst lined by a multistratified epithelium arranged in solid, pseudopapillary, cribriform, and 'incomplete cribriform/microcystic' patterns. Tumor cells were CAM5.2+, EMA+, mammaglobin+, AR+, p63+ (focal), CK5+ (focal), p53 (+, 20%), ER-, PR-, S100 protein-, DOG1-, and Her-2-. A continuous peripheral layer of p63+/CK5+/SMA+ myoepithelial cells proved the 'in situ' nature of the tumor. The evidence of focal severe nuclear atypia, high mitotic index (12 mitoses/10HPFs), and high proliferation index (40%) favored a high-grade intraductal carcinoma. Preoperative FNAC and clinic-pathologic correlation are very helpful. Discrepancy in dysplasia grade between FNAC and resected specimen can occasionally occur (especially in case of focal high-grade features). Total sampling should exclude invasive areas or other cystic malignancies.

Cytopathological findings of proliferating pilomatricoma misdiagnosed as a malignant parotid gland tumor.

BACKGROUND: Pilomatricoma is a relatively common benign cutaneous adnexal neoplasm with differentiation towards the hair matrix, inner sheath of hair follicle and hair cortex. Proliferating pilomatricoma is a rare variant of pilomatricoma that can rapidly increase and may be misidentified as a malignant tumor. We herein report the cytopathological findings of proliferating pilomatricoma misdiagnosed as a malignant parotid tumor. CASE PRESENTATION: A 64-year-old man noticed an acne-like nodule in the left parotid region. It was painless, but it increased to a maximum diameter of 4.5 cm over 2 years. Clinically, left parotid gland carcinoma was suspected, and fine-needle aspiration cytology was performed. Clusters of epithelial cells were observed in a necrotic background, and malignant epithelial cells derived from salivary glands were suspected. Histologically, the resected tumor was diagnosed as proliferating pilomatricoma composed of basophilic cells and shadow cells apart from the parotid gland. However, on a re-evaluation of the cytological specimens, the irregular-shaped epithelial cells were considered to be from basophilic cells. Shadow cells with nuclear disappearance were also confirmed. Tumor recurrence and metastasis have not been observed in the four years since surgery. CONCLUSION: The present case was first interpreted as a malignant parotid gland tumor, but it was actually a benign skin appendage tumor. Pilomatricoma sometimes rapidly increases and may be mistaken for a malignant tumor. Although it is critical to recognize not only basophilic cells but also shadow cells, it cannot be diagnosed by cytological findings. The final diagnosis should be made on excision specimen only.

[Clinicopathologic and molecular genetic analysis of secretory carcinoma of salivary gland].

Objective: To investigate the clinicopathologic and molecular genetic features of secretory carcinoma of salivary gland (SCSG). Methods: Six cases of SCSG were collected from Zhejiang Provincial People's Hospital from January 2011 to March 2018. The clinical, histopathological and immunohistochemical features were analyzed and fluorescence in situ hybridization (FISH) was used to detect ETV6 gene rearrangement. Results: Four out of 6 tumors originated in the parotid gland and one of each in the minor salivary glands of soft palate and the buccal mucosa. Grossly, 4 cases were solid and 2 were partially cystic with maximum diameter ranging from 1.0 to 4.0 cm. Microscopically, 5 tumors showed typical features of low grade SCSG with tumor divided by thin fibrous septa into lobules composed of solid acinar, microcystic, follicular and papillary structures with abundant extracellular mucinous secretions. The tumor cells had cuolated or hobnail cytoplasm with low-grade nuclei and scarce mitoses. Perineural invasion was present in 1 case. The remaining tumor showed about 30% of the tumor areas with high-grade transformation characterized by proliferation of a distinct population of anaplastic cells arranged in irregular glandular, small nested and single cell patterns that were surrounded by desmoplastic stroma and invaded into surface mucosa with ulceration. Immunohistochemistry showed that all 6 tumors had diffuse and strong reactivities to S100 protein and cytokeratin 7, and 4 cases showed focal reactivity to gross cystic disease fluid protein 15 (GCDFP15), all were negative for discovered on gist 1 (DOG1), cytokeratin 20, p63 and calponin. High grade transformation cases were analysed, the high grade SCSG components showed a significantly increased Ki-67 index and cyclin D1 positive tumor cells compared to the conventional SCSG components. FISH analyses showed that 4 cases had ETV6 gene rearrangement. Eleven to seventy one months' follow-up showed no evidence of tumor recurrence nor metastasis. Conclusions: SCSG harbors characteristic genetic abnormalities with ETV6 gene rearrangement and typically shows a low grade morphology with occasionally, high grade transformation can be present.

No evidence for human papillomavirus having a causal role in salivary gland tumors.

BACKGROUND: Salivary gland malignancies are a very heterogeneous group of cancers, with histologically > 20 different subtypes, and prognosis varies greatly. Their etiology is unknown, however, a few small studies show presence of human papillomavirus (HPV) in some subtypes, although the evidence for HPV having a causal role is weak. The aim of this study was to investigate if HPV plays a causal role in the development of different parotid salivary gland tumor subtypes. METHODS: DNA was extracted from 107 parotid salivary gland formalin fixed paraffin embedded tumors and 10 corresponding metastases, and tested for 27 different HPV types using a multiplex bead based assay. HPV DNA positive tumors were stained for p16INK4a overexpression by immunohistochemistry. RESULTS: One of the 107 malignant parotid salivary gland tumors (0.93%) and its corresponding metastasis on the neck were positive for HPV16 DNA, and both also overexpressed p16INK4a. The HPV positive primary tumor was a squamous cell carcinoma; neither mucoepidermoid nor adenoid cystic tumors were found HPV positive. CONCLUSIONS: In conclusion, HPV DNA analysis in a large number of malignant parotid salivary gland tumors, including 12 different subtypes, did not show any strong indications that tested HPV types have a causal role in the studied salivary gland tumor types.

[A rare parotid tumor]. / Une tumeur parotidienne rare.

INTRODUCTION: Sebaceous lymphadenoma of the parotid (SLP) is a rare, benign tumor with similar epidemiological and macroscopic characteristics with other sebaceous differentiated tumors of the parotid (SDTP). The authors report a case of SLP in an 80-year-old woman. They then recall the distinctive histological and immunohistochemical criteria of SDTP. OBSERVATION: Mrs P. D. was received during a surgical consultation for the management of a painless right parotid swelling that has evolved for 10years, increasing slightly in volume. At admission, the mass was movable, firm with a healthy skin without facial paralysis or satellite lymphadenopathy. The surgical intervention performed removed a nodular mass measuring 7cm, encapsulated, yellowish. It was made of regular epithelial cells without atypia or mitoses organized in nests, trabeculae and massifs. This tumor also included small canalicular cystic dilatations associated with several islands of sebaceous glands. The stroma was dense lymphoid with follicles and germinal centers. The tumor cells were CK7+, P63+, MSA+ and had a Ki67<5%. The diagnosis of an SLP was retained. No additional therapy was performed. One year after surgery, the patient had no local recurrence or metastatic foci. CONCLUSION: SLP is a rare tumor with a particular histological and immunohistochemical profile. It is an epithelial tumor with sebaceous islands, a dense reactional lymphoid stroma, expression of luminal and basal epithelial markers and a low proliferation index.

NUT Carcinoma of the Salivary Glands: Clinicopathologic and Molecular Analysis of 3 Cases and a Survey of NUT Expression in Salivary Gland Carcinomas.

NUT carcinoma (NC) represents a rare subset of highly aggressive poorly differentiated carcinomas characterized by rearrangement of the NUT (aka NUTM1, nuclear protein in testis) gene, most commonly fused to BRD4. Originally described as a mediastinal/thymic malignancy, NC has been reported at a variety of anatomic regions including the upper and lower aerodigestive tract. To date, only 7 NC cases of probable salivary gland origin have been reported. We herein describe 3 new cases (all affecting the parotid gland) in 2 women (39- and 55-y old) and 1 man (35-y old). Histologic examination showed poorly differentiated neoplasms composed of poorly cohesive small-sized to medium-sized cells with variable squamoid cell component that was focal and abrupt. Immunohistochemistry showed uniform expression of p63 and distinctive punctate expression of the NUT antigen in the tumor cell nuclei. Review of the reported salivary gland NC cases (total, 10) showed a male:female ratio of 1.5:1 and an age range of 12 to 55 years (median, 29 y). Site of the primary tumor was the parotid (7), sublingual (2), and submandibular (1) glands. All presented as rapidly growing masses treated by surgery followed by adjuvant radiotherapy/chemotherapy. Initial nodal status was positive in 8/10. At last follow-up (1 to 24 mo; median, 5 mo), 7/10 patients died of disease at a median of 5.5 months (1 to 24 mo) and only 2 were disease free at 7 and 14 months. Of 9 cases with genetic data, the fusion partner was BRD4 (n=7), non-BRD4/3 (n=1), or undetermined (n=1). None of 306 carcinomas spanning the spectrum of salivary carcinoma types screened by NUT immunohistochemistry was positive. This is the first small series on salivary NC highlighting the importance to include this rare disease in the differential diagnosis of poorly differentiated salivary gland carcinomas and in cases of presumable poorly differentiated carcinoma of unknown origin.

Oncocytic papillary cystadenoma with prominent mucinous differentiation of parotid gland: A case report.

We describe the case of an oncocytic papillary cystadenoma with mucinous differentiation of the parotid gland in a 64-year-old male. Histologically, the tumor exhibited distinctive areas of intracystic papillary growth pattern with microcystic and macrocystic spaces containing mucinous secretions and small crystals. The cyst wall and papillary fronds were lined by oncocytic admixed with numerous mucocytes. Lymphoid tissue and invasive features were not identified. The tumor showed strong expression of CK7 and mammaglobin in oncocytes, and BRST-2 and MUC4 in mucocytes. p63, ER, PR, SOX10, DOG-1, and S100 stains were negative. No rearrangement of the MAML2 gene region or ETV6-NTRK3 fusion transcript was detected. The diagnosis of oncocytic papillary tumor with prominent mucinous differentiation is particularly problematic owing to the large number of potential mimics and should prompt consideration of appropriate molecular studies.

Clinical evaluation of salivary carbohydrate antigen 125 and leptin in controls and parotid tumours.

OBJECTIVES: We determined the correlation between saliva and serum for CA125 and leptin, and evaluated their clinical screening potential for parotid tumours. SUBJECTS AND METHODS: Serum, acid-stimulated bilateral parotid saliva and chewing-stimulated whole saliva were collected and measured the levels of CA125 and leptin with electrochemiluminescence immunoassay and enzyme-linked immunosorbent assay for healthy controls and patients with unilateral parotid tumour. Intra- and intergroup comparisons were made among them. Correlations and receiver operating curve analyses were also conducted. RESULTS: There was no correlation between salivary and serum CA125 (r = -0.157-0.265, P > 0.05), while significant correlation was found for leptin (r = 0.219-0.761, P < 0.05). Leptin levels in tumour parotid saliva and CA125 levels in whole saliva were elevated significantly (P < 0.001) and showed screening potential for parotid tumours. Salivary and serum leptin levels were significantly higher in women than in men (P < 0.001). CONCLUSIONS: Salivary CA125 might originate primarily from salivary gland and tumour rather than from blood, while salivary leptin might originate from both blood and salivary gland. Multiple sources might contribute to the significantly elevated CA125 in whole saliva. Whole saliva CA125 and parotid saliva leptin reflected the occurrence of parotid tumours, while serum CA125 and leptin did not. Salivary CA125 and leptin could not distinguish malignant parotid tumours. When detecting leptin level, the influence of subjects' sex must be considered.

[A bilateral epithelial myoepithelial carcinoma of the parotid gland]. / Une localisation parotidienne bilatérale d'un carcinome épithélial myoépithélial.

We report the case of a 52-year-old man, who was admitted in the department of otorhinolaryngology for a mass of the right parotid gland. The radiological and clinical hypothesis was a squamous cell carcinoma. Histopathological examination revealed a biphasic proliferation composed of epithelial cells arranged in a tubular pattern stained with cytokeratins 5-6 and 7 and EMA surrounded by clear myoepithelial cells stained with smooth muscle actin and p63. Ki-67 labeling index was low. The diagnosis of epithelial myoepithelial carcinoma was proposed. One year after, the patient noticed a centimetric mass of the left parotid gland. The radiological hypothesis was the presence of an intraparotidian lymph node. Histopathological examination showed a second epithelial myoepithelial carcinoma. This is an uncommon neoplasm comprising approximately 1% of all salivary gland tumours, affecting mainly the parotid gland. It is occurring preferably in patients older than 60years old. This is a low-grade malignant tumour with tendency to local recurrence and lymph node metastatic potential. We describe an exceptional bilateral epithelial myoepithelial carcinoma of the parotid gland.

Cytopathology in the diagnostic appraisal of uncommon malignant neoplastic lesions.

Cytology and fine needle aspiration (FNA) cytology are accepted means of diagnosing and typing of common forms of malignant tumors. However, their usefulness for diagnosing less common neoplasms is not clearly established and this study was designed to examine this. We report four unusual cases of patients with malignant neoplasms in which cytology and fine needle aspiration cytology or aspiration biopsy (FNAC, FNAB) contributed significantly in establishing the diagnosis. These cases facilitate the diagnostic capabilities of cytology over a wide spectrum of neoplasms including rare lymphoproliferative disorders and carcinomas.

Warthin-like Mucoepidermoid Carcinoma: A Combined Study of Fluorescence In Situ Hybridization and Whole-slide Imaging.

There has been some debate as to whether a subset of metaplastic Warthin tumors (mWTs) harbor the mucoepidermoid carcinoma (MEC)-associated CRTC1-MAML2 fusion. We analyzed 15 tumors originally diagnosed as mWT (mWT-like tumors), 2 of which had concurrent MECs. We looked for the CRTC1/3-MAML2 fusion transcripts and performed immunohistochemistry for p63 and fluorescence in situ hybridization (FISH) for the MAML2 split. To localize MAML2 split-positive cells at the cellular level, whole tumor tissue sections were digitalized (whole-slide imaging [WSI]). The CRTC1-MAML2, but not CRTC3-MAML2 was detected in 5/15 mWT-like tumors. FISH-WSI results showed that all epithelial cells harbored the MAML2 split in fusion-positive mWT-like tumors and were totally negative in fusion-negative mWT-like tumors. A review of the hematoxylin and eosin-stained slides showed that morphology of the "metaplastic" epithelium was virtually indistinguishable between fusion-positive and fusion-negative tumors. However, oncocytic bilayered tumor epithelium, characteristic to typical WT, was always found somewhere in the fusion-negative tumors but not in the fusion-positive tumors. This distinguishing histologic finding enabled 5 pathologists to easily differentiate the 2 tumor groups with 100% accuracy. The age and sex distribution of fusion-positive mWT-like tumor cases was similar to that of fusion-positive MEC cases and significantly different from those of fusion-negative mWT-like tumor and typical WT cases. In addition, only fusion-positive mWT-like tumors possessed concurrent low-grade MECs. In conclusion, a subset of mWT-like tumors were positive for the CRTC1-MAML2 fusion and had many features that are more in accord with MEC than with WT. The term Warthin-like MEC should be considered for fusion-positive mWT-like tumors.

Intraparotid classical and nodular lymphocyte-predominant Hodgkin lymphoma: pattern analysis with emphasis on associated lymphadenoma-like proliferations.

Most of the lymphoproliferative diseases involving the salivary glands represent indolent non-Hodgkin B-cell lymphoma (marginal zone lymphoma) related to chronic autoimmune sialadenitis (Sjögren disease). Other types of non-Hodgkin lymphomas involve the salivary glands less frequently. On rare occasions, classical Hodgkin lymphoma (CHL) and nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL) present initially as a primary salivary gland mass. We analyzed a series of CHL (n=3) and NLPHL (n=6) presenting initially as parotid gland tumors concerning their pattern (parenchymal vs. intraparotid lymph node) and the presence of salivary inclusions and epithelial proliferations within the lymphoma infiltrate. The pattern of infiltration was determined on hematoxylin and eosin-stained slides assisted by immunostaining for pancytokeratin to highlight lobular salivary gland parenchyma. Patients included 6 male and 3 female individuals with a mean age of 62 years (range, 36 to 88 y). Lymphoma was localized within intraparotid lymph nodes in 8 cases and was limited to salivary parenchyma in 1 case. Parenchymal involvement in nodal-based cases was scored as absent (3) or minimal (5). Salivary inclusions (acini and ductules) within affected lymph nodes were noted in 6 cases (4/5 NLPHLs and 2/3 CHLs). In 3/6 NLPHL cases, salivary inclusions showed variable proliferative changes ranging from prominent lymphoepithelial lesions to cystic and oncocytic (Warthin-like) epithelial changes. Scanty small lymphoepithelial lesions were seen in 1 of the 3 CHL cases. One NLPHL in the intraparotid lymph node was accompanied by prominent lymphoepithelial sialadenitis in the absence of clinical signs of Sjögren disease. This study highlights that a majority of parotid gland Hodgkin lymphomas arise within intraparotid lymph nodes. Frequent entrapment and proliferation of salivary ducts and acini within the lymphoma infiltrate might mimic a variety of benign lymphoepithelial mass-forming lesions (nonsebaceous lymphadenoma, Warthin tumor, and autoimmune sialadenitis). Pancytokeratin stain is helpful for reliable assessment of the background architecture.