Background: Mammary analogue secretory carcinoma (MASC) is a new disease among tumours affecting the salivary glands. It was first reported in 2010, and few cases have been reported worldwide. MASC is often incorrectly diagnosed as salivary gland acinic cell carcinoma. We present here the case of a patient with an asymptomatic parotid tumour who underwent a parotidectomy of the superficial lobe.

Case report: A 78-year-old female patient came to the clinic for a tumour of approximately 2.5 × 2.5 cm and a hard, elastic consistency that had grown insidiously in the right preauricular region. Magnetic resonance imaging of the head and neck showed a heterogeneous ovoid lesion located in the lower part of the superficial lobe of the right parotid gland, measuring 29 × 27 × 27 mm. A superficial parotidectomy was performed with the facial nerve identified and preserved. Immunohistochemistry was positive for S100, mammaglobin, periodic acid Schiff (PAS) and GATA-3. Fluorescence in situ hybridisation analysis was subsequently performed and Translocation-ETS-Leukemia Virus (ETV6) gene rearrangement observed. These findings were consistent with diagnosis of a MASC. The patient then required no new interventions or adjuvant therapy. At publication, she was free of disease and continues in clinical follow-up.

Conclusion: MASC is a tumour of the saliva glands that is recently described and rare. There are no studies that describe its biological behaviour or prognosis precisely.