A Parotid Puzzle - Mammary Analogue Secretory Carcinoma in Parotid Gland

MASC (Mammary Analogue Secretory Carcinoma) is a recently recognized tumor of salivary glands with morphological, immunohistochemical and molecular characteristics similar to secretory carcinoma of the breast. Case report: A 49-year-old male presented with a painless mass in the right parotid region. On FNAC, it was reported as a Warthin tumor. Superficial parotidectomy was done and sent for histopathological examination, where it was reported as MASC. MASC of salivary glands was first described by Skalova et al., in 2010.[1] Skálová et al looked into a variety of salivary gland cancers and found that while MASC and acinar cell carcinoma share similarities, they are distinct entities with different histological features.[1] Because of the tumor's remarkable morphologic, immunohistochemical, and molecular resemblance to breast secretory carcinoma, it was given that name.[2] It has been demonstrated that a recurring balanced chromosomal translocation t (12;15) (p13; q25) in secretory carcinoma of the breast results in an oncogenic fusion gene ETV6-NTRK3. In MASC, this translocation is also found.[3] A chimeric tyrosine kinase that is encoded by this fusion gene is known to be crucial to its carcinogenesis.[4] MASC and breast SC share immunohistochemical characteristics, such as having S100 protein, EMA (Epithelial Membrane Antigen), vimentin positive, and being "triple negative" (ER/PR/Her2 negative).[5] The parotid gland is the primary site of MASC, a rare malignant tumor of the salivary glands, which is followed by the submandibular gland, minor salivary gland, and accessory parotid gland.[6,7] Men are most frequently affected by MASC, and they typically do not act aggressively.[8] A slowly expanding solid mass and the absence of pain are the clinical signs of MASC. Due to the relatively low imaging specificities and clinical characteristics, the tumor could be misdiagnosed.[9] Here we describe mammary analogue secretory carcinoma in a 49-year-old male.