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.