A Case of Mammary Analogue Secretory Carcinoma of the Upper Lip

Abstract

In 2010, Skálová et al. were the first to propose mammary analogue secretory carcinoma (MASC) as a new subtype of salivary gland carcinoma characterized by the presence of the ETV6-NTRK3 fusion gene. MASC was earlier often categorized as an unusual variant of salivary acinic cell carcinoma, because the histological appearance of MASC is sometimes similar to that of acinic cell carcinoma. Herein, we present the case of a 52-year-old male patient who presented with a submucosal tumor in the upper lip and was diagnosed as having MASC. The tumor was 1 cm in diameter and was initially diagnosed as a benign submucosal cyst in the upper lip and excised. Histopathology of the surgically resected specimen revealed the diagnosis of MASC. No additional treatment was administered to the patient and he remained free of tumor at the follow-up examination conducted 18 months after the surgery. It was difficult to suspect malignant tumor initially in this case, underscoring the importance of bearing in mind the possibility of malignant submucosal cyst in the differential diagnosis. It is important to keep in mind the possibility of MASC in patients presenting with a submucosal cyst of the lip.