Carcinoma ex pleomorphic adenoma of the buccal region is composed of salivary duct carcinoma and squamous cell carcinoma components.

A 73-year-old female presented with an asymptomatic mass in the left buccal region that she had first noticed 4 years earlier. The tumor, which was located in the buccal space, was clinically diagnosed as a salivary gland tumor and treated by excision. Histopathological examination revealed a capsule of connective tissue consisting of three different histopathological neoplastic areas in a large, fibrous, hyalinizing stromal background. The neoplastic lesion contained two malignant and one benign element, with histological characteristics consistent with squamous cell carcinoma (SCC), salivary duct carcinoma (SDC) and pleomorphic adenoma (PA). The SCC nests showed no continuity with the buccal mucosa. Both the SCC and SDC nests were surrounded by non-atypical myoepithelial cells, suggesting that both components may have developed from transformation of metaplastic luminal epithelial cells of PA. The tumor was diagnosed as a non-invasive carcinoma (SCC and SDC) ex pleomorphic adenoma (Ca-ex-PA). There was no evidence of recurrence 16 months after operation.