Sarcomatoid Carcinoma of Gallbladder

Undifferentiated Carcinoma: Undifferentiated carcinomas of the gallbladder may be sarcomatoid type or epithelioid type. Areas of conventional adenocarcinoma are also usually present. Sarcomatoid carcinomas have a prominent spindle cell component that can range from low-grade, fibroblastic areas to high-grade pleomorphic sarcoma. Areas of heterologous differentiation (bone, cartilage, skeletal muscle, and angiosarcoma-like) are commonly present.

This image of sarcomatoid carcinoma shows areas of conventional adenocarcinoma in a spindle cell stroma that is reminiscent of undifferentiated pleomorphic sarcoma.