Papillary urothelial bladder carcinoma associated with osteoclast-like giant cells

We report the case of a papillary urothelial carcinoma associated with osteoclast-like giant cells. A 60-year old woman presented with hematuria. A papillary neoplasm was detected by cystoscopy and removed transurethrally. Histological examination revealed a papillary urothelial carcinoma (grade I) associated with multiple stromal giant cells, which displayed morphological, ultrastructural and immunohistochemical characteristics of osteoclast-like giant cells. The formation of osteoclast-like giant cells in association with urothelial bladder carcinoma is a rare event, of which only six cases have been reported in the Anglo-American literature. It may cause diagnostic problems because primary giant cell tumor, giant cell carcinoma and foreign body stromal reaction have to be considered. Immunohistochemistry and electron microscopy may help to rule out these differential diagnoses.