RESUMO
Mammary analogue secretory carcinoma (MASC) is a recently described salivary gland tumour that harbours the recurrent ETV6-NTRK3 translocation. This is the first series of MASC cases identified in the historic cohort of carcinomas of salivary glands with clinical/pathological correlation and follow-up data. We reviewed 183 primary carcinomas of major and minor salivary glands resected at the Medical University of Gdansk, Poland, between 1992 and 2012. Based on morphology and immunohistochemistry, cases suspicious for MASC were selected, and the diagnosis was confirmed by fluorescence in situ hybridization (FISH) for ETV6 rearrangement and by RT-PCR for the ETV6-NTRK3 fusion transcript. Seven carcinomas met the criteria of MASC, as they exhibited a typical appearance with solid/microcystic and papillary architecture and intraluminal secretions, and cells completely devoid of basophilic cytoplasmic zymogen granules indicative of true acinar differentiation. The only paediatric case was an unencapsulated tumour composed of macrocystic structures covered by a mostly single but, focally, double layer of cells with apocrine morphology. In all cases, the neoplastic cells revealed immunoreactivity for S100, mammaglobin, cytokeratin CK7, CK8, STAT5a and vimentin. FISH for ETV6 gene rearrangement was positive in six out of seven cases, and RT-PCR was positive in three cases. MASC is a new entity of malignant epithelial salivary gland tumours not included in the 2005 WHO Classification of Head and Neck Tumours. There is a growing body of evidence that it is not as rare as was assumed, as is also indicated by our series (3.8 %). In most cases, MASC shares some microscopic features with AciCC, adenocarcinoma/cystadenocarcinoma NOS and low-grade MEC. In rare cases, MASC with high-grade transformation may mimic the morphological appearances of high-grade salivary gland malignancies, such as salivary duct carcinoma.
Assuntos
Neoplasias da Mama/classificação , Neoplasias da Mama/genética , Carcinoma/classificação , Carcinoma/genética , Rearranjo Gênico/genética , Proteínas Proto-Oncogênicas c-ets/genética , Proteínas Repressoras/genética , Neoplasias das Glândulas Salivares/classificação , Neoplasias das Glândulas Salivares/genética , Adolescente , Adulto , Idoso , Biomarcadores Tumorais/metabolismo , Neoplasias da Mama/metabolismo , Carcinoma/metabolismo , Feminino , Seguimentos , Fusão Gênica/genética , Humanos , Queratinas/metabolismo , Masculino , Pessoa de Meia-Idade , Proteínas Proto-Oncogênicas c-ets/metabolismo , Receptor trkC/genética , Proteínas Repressoras/metabolismo , Estudos Retrospectivos , Proteínas S100/metabolismo , Fator de Transcrição STAT5/metabolismo , Neoplasias das Glândulas Salivares/metabolismo , Translocação Genética/genética , Proteínas Supressoras de Tumor/metabolismo , Vimentina/metabolismo , Adulto Jovem , Variante 6 da Proteína do Fator de Translocação ETSRESUMO
This study examines the presence of the EWSR1 rearrangement in a variety of clear cell salivary gland carcinomas with myoepithelial differentiation. A total of 94 salivary gland carcinomas with a prominent clear cell component included 51 cases of clear cell myoepithelial carcinomas de novo (CCMC), 21 cases of CCMCs ex pleomorphic adenoma (CCMCexPA), 11 cases of epithelial-myoepithelial carcinoma (EMC), 6 cases of EMC with solid clear cell overgrowth, and 5 cases of hyalinizing clear cell carcinoma of minor salivary glands. In addition, 10 cases of myoepithelial carcinomas devoid of clear cell change and 12 cases of benign myoepithelioma were included as well. All the tumors in this spectrum were reviewed, reclassified, and tested by fluorescence in situ hybridization (FISH) for the EWSR1 rearrangement using the Probe Vysis EWSR1 Break Apart FISH Probe Kit. The EWSR1 rearrangement was detected in 20 of 51 (39%) cases of CCMC, in 5 of 21 (24%) cases of CCMCexPA, in 1 of 11 (9%) cases of EMC, and in 4 of 5 (80%) cases of hyalinizing clear cell carcinoma. The 25 EWSR1-rearranged CCMCs and CCMCexPAs shared similar histomorphology. They were arranged in nodules composed of compact nests of large polyhedral cells with abundant clear cytoplasm. Necrosis, areas of squamous metaplasia, and hyalinization were frequent features. Immunohistochemically, the tumors expressed p63 (96%), cytokeratin CK14 (96%), and S100 protein (88%). MIB1 index varied from 10% to 100%, with most cases in the 20% to 40% range. Clinical follow-up information was available in 21 cases (84%) and ranged from 3 months to 15 years (mean 5.2 y); 4 patients were lost to follow-up. Ten patients are alive with no evidence of recurrent or metastatic disease in the follow-up period from 3 months to 15 years (mean 5 y), 3 patients are alive with recurrent and metastatic disease, and 8 died of disseminated cancer 9 months to 16 years after diagnosis (mean 6 y). Lymph node metastasis appeared in 5 patients within 5 months to 4 years after diagnosis (mean 22 mo), distant metastases were noted in 7 patients with invasion of orbit (2 cases), and in 1 case each metastasis to the neck soft tissues, liver, lungs, mediastinum, and thoracic vertebra was noted. We describe for the first time EWSR1 gene rearrangement in a subset of myoepithelial carcinomas arising in minor and major salivary glands. The EWSR1-rearranged CCMC represents a distinctive aggressive variant composed predominantly of clear cells with frequent necrosis. Most EWSR1-rearranged CCMCs of salivary glands are characterized by poor clinical outcomes.