Prognostic factors of recurrence in salivary carcinoma ex pleomorphic adenoma, with emphasis on the carcinoma histologic subtype: a clinicopathologic study of 43 cases

Abstract

Carcinoma ex pleomorphic adenoma is a rare salivary gland neoplasm, especially when the malignant component is only intracapsular/minimally invasive. Moreover, only few studies have assessed the behavior of carcinoma ex pleomorphic adenoma according to the histologic subtype. Forty-three cases of carcinoma ex pleomorphic adenoma were identified over a 27-year period and subjected to a detailed histopathologic analysis. There were 13 intracapsular/minimally invasive and 30 widely invasive carcinomas. There were 15 myoepithelial carcinomas, 25 salivary duct carcinomas, 2 adenocarcinomas not otherwise specified, and 1 carcinosarcoma. There was a trend toward a higher frequency of myoepithelial carcinomas in widely invasive tumors (13/30, 43%) than in intracapsular/minimally invasive (2/13, 15%) carcinoma ex pleomorphic adenoma (P = .095). Adequate follow-up was available for 38 patients. Vascular invasion and distant metastases correlated with decreased disease-free survival and disease-specific survival (P < .05), whereas the extent of invasion and the presence of a high mitotic rate or atypical mitoses correlated with decreased disease-free survival only (P < .05). There was a trend toward worse disease-free survival and disease-specific survival in patients with myoepithelial carcinoma (P = .08). Within the intracapsular/minimally invasive carcinoma ex pleomorphic adenoma group, both myoepithelial carcinoma (2/2, 100%) had metastatic disease, whereas only 1 of 11 nonmyoepithelial carcinoma relapsed (P = .038). Vascular invasion, high mitotic rate, and histologic subtype were found to correlate with recurrence in carcinoma ex pleomorphic adenoma. Patients with intracapsular/minimally invasive tumor have a more favorable outcome than patients with widely invasive neoplasm, but intracapsular/minimally invasive carcinoma ex pleomorphic adenoma can recur and cause death. The presence of myoepithelial carcinoma subtype increases the risk of recurrence in carcinoma ex pleomorphic adenoma, especially within the group of intracapsular/minimally invasive tumors.