Anaplastic carcinoma of the pancreas associated with a mucinous cystic adenocarcinoma. A case report and review of the literature.

CONTEXT Anaplastic carcinoma of the pancreas is a rare undifferentiated variant of ductal adenocarcinoma, which commonly displays sarcomatoid spindle-cell and pleomorphic growth patterns. Anaplastic carcinoma of the pancreas associated with mucinous cystic neoplasm has rarely been reported. CASE REPORT Here we report a unique case of an anaplastic carcinoma of the pancreas in association with a mucinous cystadenocarcinoma in a 70-year-old woman. The anaplastic component of this tumor is predominantly composed of spindle cells and highly pleomorphic cells that mimic a spindle cell sarcoma. The spindle neoplastic cells have strong expression of vimentin and mucin 1 and focal strong positivity of CK7 and CK20. Scattered osteoclast-like giant cells are admixed with the spindle cells with positivity for CD68 but not epithelial or other mesenchymal markers. Focal squamoid differentiation is present. Adjacent to the solid anaplastic tumor is a classic mucinous cystadenocarcinoma, which has strong reactivity to mucin 1, CA 19-9, epithelial membrane antigen (EMA), CK19, CK8/18, carcinoembryonic antigen and CK7. The peri-cystic tissue and the septa consist of an ovarian-type stroma that is strongly positive for CD10. Focal areas with pancreatic intraepithelial neoplasia IB (PanIN-IB) changes are seen in the adjacent normal pancreatic tissue. CONCLUSION The anaplastic carcinoma of the pancreas is of epithelial origin with various microscopic features, and the scattered osteoclast-like giant cells in the tumor are reactive cells of histiocytic origin.