Dedifferentiated acinic cell carcinoma of the parotid gland with myoepithelial features.

Dedifferentiated acinic cell carcinoma of the salivary gland is an uncommon variant of acinic cell carcinoma, characterized by the coexistence of both an usual low-grade acinic cell carcinoma and a high-grade dedifferentiated component, as well as by an accelerated clinical course. We describe a case of acinic cell carcinoma of the parotid gland in a 67-year-old woman, which recurred 4 times after surgery and radiotherapy. The recurrences consisted of residual foci of acinic cell carcinoma intermingled with a high-grade epithelial proliferation; the latter was focally constituted by cells with morphologic and immunohistochemical features of myoepithelium.