Mixed osteoclastic/pleomorphic-type giant cell tumor of the pancreas with ductal adenocarcinoma: histochemical and immunohistochemical study with review of the literature.

We described a rare form of giant cell tumor of the pancreas composed of mixed osteoclastic/pleomorphic-type giant cell tumor with ductal adenocarcinoma. Immunohistochemical study showed positive staining of cytokeratin and epithelial membrane antigen for pleomorphic-type giant cells and ductal adenocarcinoma but negative for osteoclastic-type giant cells. Vimentin stained positive in both types of giant cells but negative in adenocarcinoma. Osteoclastic-type giant cells were strongly positive for CD68 and tartarate-resistant acid phosphatase was present in these cells, suggesting the osteoclast-like character. CD68 was negative for both pleomorphic-type giant cells and ductal adenocarcinoma. From these findings, we consider that this tumor might be a carcinosarcoma-like neoplasm consisting of both an epithelial and a histiocytic-mesenchymal component.