A Case of Mammary-Analogue Secretory Carcinoma of the Parotid Gland

Abstract

Salivary gland carcinoma was originally classified as acinic cell carcinoma because of its histological similarity to secretory breast carcinoma. However, in 2010, Skalove et al. characterized this tumor as mammary-analogue secretory carcinoma, because like secretory breast carcinoma, it often expresses the ETV6-NTRK3 fusion oncogene. We encountered a case of mammary-analogue secretory carcinoma arising from the parotid gland. This specific diagnosis was made because (1) a follicular variant was present, (2) physaliphorous cells were observed, (3) no zymogen granules were observed, (4) the mucoid discharge in the follicular lumen was D-PAS-positive, and (5) the tumor showed immunostaining characteristics consistent with those of mammary-analogue secretory carcinoma (e.g., positive for S-100 and adipophilin). No additional treatment was administered to the patient after the resection, as the tumor is known to show a low malignancy potential and the surgical margins were negative. Tumor recurrence or metastasis has not been observed until date.