Small mammary analogue secretory carcinoma arising from minor salivary gland of buccal mucosa

Mammary analogue secretory carcinoma (MASC) of salivary gland has been identified at 2010 by Skálová et al. There are only four cases occurring in buccal mucosa among the previously reported 70 cases. In this article, we present such fifth case. A 59-year-old Japanese man noticed the nodule measuring 5 mm in maximum diameter of the left buccal mucosa and subsequent biopsy showed the finding of tubular and microcystic configurations of the tumor cells. Secretory materials in glandular lumens were positive for periodic acid–Schiff stain with and without diastase treatment. Immunohistochemically, neoplastic cells demonstrated diffuse immunolabeling for vimentin, cytokeratin 7, cytokeratin 19 and S-100 protein. Additionally, the bilayer structure of CD34-positive stromal cells and alpha-smooth muscle actin-positive myofibroblasts in the capsule was identified. Finally, otolaryngologists and oral surgeon should bear in mind that MASC may occasionally arise from buccal mucosa. CD34-positive stromal cells and myofibroblasts may be associated with the regulation of tumor growth of MASC, like other salivary gland tumors. This is the smallest tumor among the previously reported cases.