Clinicopathological characterization of mammary analogue secretory carcinoma of salivary glands

Aims: Mammary analogue secretory carcinoma (MASC) is a recently described tumour with ETV6 translocation. We aimed to characterize the clinical significance of recognizing MASC. Methods and results: Thirty-six patients with MASC (27 identified retrospectively and nine prospectively) are presented. Historically, MASC mimicked other salivary tumours, as follows: 14 of 37 (37.8%) adenocarcinoma, not otherwise specified, 11 of 89 (12.4%) acinic cell carcinomas (AciCC), one of five (20%) mucin-producing signet ring adenocarcinomas, and one of 165 (0.6%) mucoepidermoid carcinomas. Demographically, MASC affected males more commonly (1.4:1). The average age at diagnosis was 45.7 years. Parotid gland was the most common site of involvement (26 of 36, 72.2%), although other head and neck sites, including the base of tongue, were affected. Of 18 patients with neck dissection, lymph node involvement was identified in four patients (four of 18, 22.2%). Survival analysis of MASC cases presented here, combined with those reported previously, revealed a mean disease-free survival for patients with MASC of 92 months [n = 29; 95% confidence interval (CI) 71115 months], compared with a mean DFS of 121 months for patients with AciCC (n = 38; 95% CI 92149, P = 0.43). Conclusions: Although perhaps slightly more aggressive, MASC clinical outcome mimics that of AciCC.