Image 52 of 146



Image Description

High-grade transformation is seen in about 10% of well-differentiated acinic cell carcinomas, usually in older patients with long-standing or recurrent tumors. It is often heralded by a period of rapid growth, fixation to surrounding tissues, pain, and facial paralysis. Rarely, high-grade morphology may be seen at the time of initial presentation. The tumor usually consists of areas of conventional (low-grade) acinic cell carcinoma with associated high-grade carcinoma. The high-grade areas are composed of undifferentiated or poorly-differentiated cells with solid or trabecular growth pattern (as shown here). Increased mitotic activity (including atypical mitotic figures) and necrosis may be present. The prognosis is usually poor.

Image 52 of 146