Image Description
Small Cell Carcinoma: Poorly-differentiated neuroendocrine carcinomas (NECs) of gallbladder and biliary tract can show small cell or large cell phenotype, similar to those in the lungs and other sites. Most are pure small cell carcinomas (shown here) with typical morphology consisting of cells with hyperchromatic nuclei, nuclear molding, finely stippled chromatin, and inconspicuous nucleoli. The cells are arranged in sheets, cords, nests and anastomosing trabeculae with scattered areas of geographic necrosis. Rosette formation as well as tubular structures may be seen. Mitotic activity is brisk (frequently >20 mitoses/10HPFs).