Mammary Analogue Secretory Carcinoma of the Parotid Gland as a Secondary Malignancy in a Childhood Survivor of Atypical Teratoid Rhabdoid Tumor

We report the first case of mammary analogue secretory carcinoma (MASC) arising as a secondary malignancy in a 14 years old child with a history of atypical teratoid rhabdoid tumor (ATRT). Although MASC and ATRT are both rare malignancies, they do not share the same genetic and molecular profiles. MASC is a salivary malignancy characterized by a t(12; 15)(p13; q25) translocation, resulting in an ETV6-NTRK3 fusion product encoding for a tyrosine kinase. ATRT is a highly malignant pediatric tumor characterized by a chromosome 22 mutation in the hSNF5/ INI1 gene, encoding for a chromatin remodeling protein. Additionally, although mucoepidermoid carcinoma has been described as a secondary malignancy post-therapy for head and neck tumors, MASC has only been reported as a primary malignancy. Our patient was treated with a complete resection of his left sided ATRT at age 3 followed postoperatively with chemoradiotherapy. At age 14 he underwent a parotidectomy for his 1 year history of a left sided preauricular mass and was subsequently diagnosed with MASC. We not only report a case of two rare malignancies in one patient, but also the first case of MASC arising as a secondary malignancy.