The Osteoclast-Type Giant Cell Rich Carcinoma of Urinary Bladder: A Case Series.

Background: Osteoclast-type giant cell-rich carcinomas (OGCRCs) of urinary bladder are extremely rare, aggressive tumors that are often diagnosed as undifferentiated carcinomas. The morphology overlaps with other giant cell-rich benign and malignant bladder lesions. Little is known about the pathogenesis and clinical management of this aggressive variant. The aim of this study was to review clinico-pathologic features, and survival characteristics in a series of OGCRCs.Materials and methods: Five cases of OGCRCs of bladder were retrospectively reviewed. Clinical presentation, histomorphology, ancillary tests, treatment and follow-up data were retrieved and analyzed.Results: All patients were adult males (age range 63-86 years) and presented with painless gross hematuria. All cases showed biphasic morphology with polygonal to epithelioid to spindle mononuclear cells (MCs) and scat-tered multinucleated osteoclast-like giant cells (OGCs). Background urothelium showed urothelial carcinoma in-situ (CIS) (4/5) and/or invasive urothelial carcinoma (UC) (2/5) and invasive high-grade papillary urothelial carcinoma (PUC) (2/5). MCs showed focal expression of at least one epithelial marker and focal/diffuse expression of urothelial markers. OGCs were positive only for histiocytic markers. Oncomine test showed presence of p53 mutation (p.R282W) in case 3. Pathologic stage was T1 (n = 3), T2b (n = 1) and T3a (n = 1). 2/5 patients died of disease within 3 years of diagnosis.Conclusions: OGCRC is an extremely rare and potentially aggressive malignant neoplasm of bladder. Most cases have associated conventional in-situ or invasive UC supporting undifferentiated or de-differentiated nature of this neoplasm. Surgery should be considered given the potential for aggressive behavior. However optimal treatment for OGCRCs remains unknown.