Fine-needle aspiration biopsy of pleomorphic (giant cell) carcinoma of the pancreas. Cytologic, immunocytochemical, and ultrastructural findings.

Four cases of pleomorphic (giant cell) carcinoma (PGC) of the pancreas, diagnosed by fine-needle aspiration biopsy, are presented. Ancillary immunocytochemical studies were also performed on the smears (four cases) and cell blocks (three cases), along with ultrastructural (electron microscopic) examination of the aspirated specimen (two cases). Three of the four patients were elderly (age range: 44-65 years), and all had large pancreatic masses. A spectrum of cytomorphologic features was encountered, including poorly cohesive bizarre mononuclear cells, many multinucleated tumor giant cells, and associated malignant spindle cells. Prominent cellular cannibalism and cytophagocytosis also were seen. Immunoperoxidase studies demonstrated dual staining of the malignant cells for cytokeratin and vimentin in two cases and exclusive staining for vimentin in the remaining two cases. Ultrastructural examination demonstrated epithelial features in both cases studied. One of the cases demonstrated intracytoplasmic whorled bundles of intermediate filaments, corresponding to pale eosinophilic globular material, appreciated both in the Diff-Quik- and Papanicolaou-stained smears and staining with positive results for vimentin. The immunocytochemical studies suggest that the coexpression of vimentin and cytokeratin within the cells is consistent with a pleomorphic malignancy of epithelial origin. It is speculated that the staining of two of the cases exclusively for vimentin can be seen in either epithelial malignancies with sarcomatoid transformation or, less likely, a pure sarcoma of the pancreas.