Primary Mammary Analog Secretory Carcinoma (MASC) of the Vulva With ETV6-NTRK3 Fusion: A Case Report.

Mammary analog secretory carcinoma is a primary salivary gland neoplasm with histologic, immunophenotypic, and molecular features identical to those of secretory carcinoma of the breast. Similar neoplasms have now been reported to occur in various nonmammary sites including the parotid gland, submandibular gland, sinuses, lip, skin, thyroid gland, and lung. We report, to our knowledge, the first example of a primary vulvar neoplasm with pathologic features identical to secretory carcinoma of the breast and an ETV6-NTRK3 fusion.