Osteoclast-rich undifferentiated carcinoma of the bladder: A case report

Abstract

Osteoclast-rich undifferentiated carcinomas of the bladder are rare, aggressive neoplasms with less than 20 cases being reported in the English literature. We report a 73-year-old woman with a history of ovarian high grade serous carcinoma at age 65 and conventional invasive urothelial carcinoma of renal pelvis at age 71, who then presented with a 3 cm left sided bladder wall tumour. The patient underwent biopsy and subsequent radical cystectomy. Histological examination revealed predominantly malignant spindle cells and malignant mononuclear cells closely intermixed with small islands of conventional invasive urothelial carcinoma. Throughout the tumour, bland osteoclast-like multinucleated giant cells were present. Background urothelium showed non-invasive high-grade papillary urothelial carcinoma. Immunohistochemistry showed cytokeratin, p40 and p53 positivity in the malignant spindled and mononuclear cells, as well as the areas of conventional invasive urothelial carcinoma. Osteoclast-like giant cells were positive for CD68 and LCA, but negative for cytokeratin, p40 and p53. Ki67 index was elevated in malignant spindle cells, mononuclear cells and conventional invasive urothelial carcinoma but completely negative in osteoclast-like giant cells. These findings give further evidence that undifferentiated spindle cells and mononuclear cells are dedifferentiated urothelial carcinomas, while bland osteoclast-like giant cells are benign stromal reaction of histiocytic lineage.