Abstract
The Clinco-pathological, immunohistochemical and molecular findings of four cases of Mammary Analogue Secretory Carcinoma (MASC) of salivary glands found in Mexico are described. The cases were extracted from 253 salivary gland tumors from a single institution in Mexico City. The 85 candidates for initial selection were: low grade mucoepidermoid carcinoma (MEC) (N=70 ), acinic cell cancinoma (AciCC) (N=14), papillary cystadenocarcinoma (N=1), and adenocarcinoma NOS (N=0). Tumors with some histological features consistent with MASC (N= 17, 6.7%) were studied by immunohistochemistry for mammaglobin, STAT5, and S-100 protein and four cases were positive (1.5%), thus the diagnosis of MASC was established, and these were submitted for molecular studies for ETV6-NTRK3. Fusion gene was demonstrated in three cases, two had been erroneously diagnosed as poorly granulated AciCC, and one as low grade MEC with microcystic pattern. Female gender predominated (3:1); one occurred in the parotid, two in minor salivary glands and one in the submaxillary gland; infiltrating borders, atypical mitosis and lymph node metastases were seen in the parotideal tumor. Two patients with major salivary gland tumors are alive and well at 10 and 20 months respectively, the two patients with minor salivary gland tumors are lost. It can be concluded that is important to think in MASC in poorly granulated AciCC and low grade MEC with microcystic pattern. Immunohistochemisty studies confirm the diagnosis, preferentially supported by molecular studies. MASC may follow aggressive behavior or transform into a high grade neoplasm. Key words:Acinic cell carcinoma, ETV6-NTRK3, Mammary Analogue Secretory Carcinoma, secretory breast carcinoma.
Highlights
Mammary Analogue Secretory Carcinoma (MASC) of salivary glands was described by Skalova et al in 2010 (1)
Molecular study demonstrated ETV6-NTRK3 fusion gene in three, and was negative in one that was still considered as MASC because of the positive result of the immunohistochemistry. -Clinical findings: Table 1 shows that the four patients complained of increase of volume lasting from 2 months to 4 years
The translocation ETV6-NRK3 is not completely specific of breast secretory carcinoma and MASC; it is present in congenital fibrosarcoma, mesoblastic nephroma, and acute myeloid leukemia (2)
Summary
Mammary Analogue Secretory Carcinoma (MASC) of salivary glands was described by Skalova et al in 2010 (1). Most cases have an specific translocation t(12; 15) (p13; q25) originating fusion of genes ETV6NTRK3 that codifies a chimeric tyrosine kinase. This genetic rearrangement has been found in congenital fibrosarcoma, mesoblastic nephroma and acute myeloid leukemia (2). MASC has been reported as a low grade tumor with microcystic, cystic-papillary, glandular, and solid patterns. Recent studies have demonstrated that MASC can bear a resemblance to other salivary gland tumors such as adenocarcinoma NOS, mucoepidermoid carcinoma (MEC), cystadenocarcinoma, and poorly granulated acinic cell carcinoma (AciCC) (1,3). In Mexico this entity has not been reported, a retrospective study was undertaken to identify cases of MASC by immunohistochemistry, and support the diagnosis with genetic studies
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