Adenocarcinoma of the pancreas with osteoclast-like giant cells: a case report with immunocytochemistry.

Histological examination of a tumor centered in the body of the pancreas of a 65-year-old Iranian man revealed it to have a substantial component in which osteoclast-like giant cells were set within a stroma of pleomorphic mononuclear cells though other areas were composed of conventional adenocarcinoma. Immunocytochemistry was used to investigate the differentiation of the various component cells of the tumor. The carcinoma cells of the usual type expressed epithelial antigens (EMA and cytokeratin). The giant cells expressed vimentin and showed membrane staining with anti-LCA, in common with examples of cells originating from the mononuclear phagocytic system, including normal osteoclasts. The accompanying stromal cells expressed vimentin only. This implies that the giant cells are likely to have their origin in the bone marrow, whereas the mononuclear stromal cells that separate them may represent tumor cells that have lost their epithelial phenotype. The giant cells are therefore an unusual tissue response to the presence of the carcinoma.