Combined osteoclastic giant cell and pleomorphic giant cell tumor of the pancreas: a rarity. An immunohistochemical analysis and review of the literature.

CONTEXT: The combination of an osteoclastic giant cell tumor and a pleomorphic giant cell carcinoma of the pancreas is distinctly unusual and is associated with an adverse outcome. The origin of these two components within a tumor has long been debated based on the immunohistochemical and ultra-structural analysis. CASE REPORT: Herein we describe a tumor with amalgamation of these two distinct histomorphologies along with a minute focus of well-differentiated ductal adenocarcinoma (on multiple sections) in a 50-year male. On immunohistochemical analysis, osteoclastic giant cells were reactive for CD68 and vimentin confirming histiocytic/mesenchymal derivation whereas pleomorphic giant cells and mononuclear cells were reactive for cytokeratin which proved their epithelial nature. CONCLUSIONS: Although the present case had an equal proportion of both components, it is very important to correctly assess the predominant histology since osteoclastic giant cell tumor has a better prognosis as compared to the more aggressive pleomorphic giant cell carcinoma component.