Outcomes of treatment of mammary analogue secretory carcinoma of the parotid gland.

Mammary analogue secretory carcinoma (MASC) of the salivary gland is a newly-described, rare, malignant tumour. Few patients present with MASC of the parotid gland, so the exact characteristics, outcomes of treatment, and prognosis are unknown. The aim of this study was to analyse the clinical features and outcomes of treatment of MASC of the parotid gland in patients being treated at a single hospital. Five patients with histopathologically-confirmed MASC of the parotid gland between January 2015 and August 2018 were retrospectively enrolled. In all cases preoperative fine-needle aspiration cytology had failed to provide an accurate diagnosis. All patients underwent a macroscopically complete oncological resection. Two patients had postoperative radiotherapy (RT). On immunohistochemical examination all tumours stained for S-100 and mammaglobin but not for DOG1. There were no regional recurrences or distant metastases in any of the patients at their last follow-up. We obtained good results for patients with MASC of the parotid gland with surgical treatment and postoperative RT.