A case of osteoclast-like giant cell tumor of the pancreas associated with borderline mucinous cystic neoplasm.

A 34-year-old, previously healthy female presented with severe acute upper quadrant abdominal pain and an 11-cm cystic mass in the tail of the pancreas. The patient underwent distal pancreatectomy with total gross excision of the mass. Grossly, the mass consisted of a multiloculated cystic lesion measuring 11.7 cm in its greatest dimension. An irregular solid lobulation at the lateral aspect of the cyst was visible, measuring 3 cm in the largest dimension. Histologically, there were two distinct components: a mucinous, neoplastic epithelial cyst with few foci of moderate atypia, and nodular spindle cell areas containing multinucleated tumor giant cells. Immunohistochemically, the multinucleated giant cells were positive for vimentin, CD68 and CD45, and negative for cytokeratin and epithelial membrane antigen (EMA). The spindle cells of hypercellular stroma were stained for vimentin, but not for EMA or carcinoembryonic antigen (CEA). Neuron-specific enolase (NSE), S100 and Ki-67 showed no reactivity. The histological diagnosis "osteoclast-like giant cell tumor of the pancreas associated with borderline mucinous cystic neoplasm" was made. The patient recovered and is free of disease 4 years after the diagnosis.