Fine-needle aspiration cytology of osteoclastic giant-cell tumor of the pancreas.

Osteoclastic giant-cell tumor (OGCT) of the pancreas is a rare tumor. We present the fine-needle aspiration (FNA) and bile cytology findings of an OGCT arising in the head of the pancreas in a 72-yr-old male, along with immunocytochemical studies that were done on the cytologic material. The smears showed numerous giant cells with clustered, overlapping, uniform, bland-appearing nuclei with prominent nucleoli consistent with osteoclastic-type multinucleated giant cells. A second population of mononucleated cells appearing singly or in groups having similar nuclear features was also present. Immunocytochemical studies performed on the FNA and bile duct fluid material demonstrated positive staining of the malignant cells for vimentin, alpha-1 antichymotrypsin, and alpha-1 antitrypsin and negative staining for high- and low-molecular-weight cytokeratin, pooled monoclonal cytokeratin, epithelial membrane antigen, and carcinoembryonic antigen. Although not definitive, these studies are supportive of a mesenchymal-stromal histogenesis of this unusual pancreatic malignancy.