FDG PET/CT in Sarcomatoid Carcinoma of the Gallbladder With Chondroid Differentiation.

Sarcomatoid carcinoma of the gallbladder, composed of epithelial and sarcomatous components, is a rare malignant tumor with a poor prognosis. A 61-year-old man was admitted because of abdominal distention for 2 weeks. Enhanced CT showed a large gallbladder tumor with central necrosis. The tumor measuring 18 cm in maximum diameter showed intense peripheral FDG uptake with SUVmax of 15.4. The specimen of the resected tumor revealed tubular adenocarcinoma and sarcomatoid tissue with chondroid differentiation. Immunohistochemical staining showed the sarcomatoid tissue was positive for EMA, CD10, and VIM, with proliferation index of 80%. These pathologic findings were consistent with sarcomatoid carcinoma.