Atypical Presentation of Mammary Analogue Secretory Carcinoma of the Lip.

Mammary analogue secretory carcinoma (MASC) of the salivary gland is a rare tumor that was first described by Skalova et al in 2010, and since then, only a few hundred cases have been reported in the literature. Prior to Skalova's report, MASC was histologically misclassified as acinic cell carcinoma (ACC), pleomorphic adenoma, mucoepidermoid carcinoma, or adenocarcinoma, not otherwise specified. Mammary analogue secretory carcinoma has a low incidence rate overall, accounting for less than 0.3% of all salivary gland tumors. Histopathologic and cytogenic analysis of MASC is identical to secretory carcinoma of the breast, leading to the proposed name by Skalova. The purpose of this case presentation is to describe an atypical presentation of MASC, to compare this case with the classic description of MASC, and to contrast the various features of MASC to ACC in order to improve the accuracy of future diagnoses and help guide treatment.