Urinary bladder leiomyosarcoma with osteoclast-like multinucleated giant cells: a case report

Bladder leiomyosarcoma is the most frequent mesenchymal neoplasm of the bladder. However, the rarity of the disease and some morphological aspects could give serious problems to differential diagnosis.

A 86-year-old male patient was referred to our institution to undergo endoscopic low-urinary-tract re-evaluation 2 months after the detection of a "low-grade urothelial neoplasia" in urinary cytology. A TURBT (transurethral resection of bladder tumor) was performed and revealed a tumor extending for 3.5 cm with thin stalk peduncle on the left lateral wall of the bladder, cephalad and lateral to the left ureteral orifice. The exophytic part of the tumor was resected with the underlying bladder wall. Histologically, the tumor showed a quite complex pattern, composed of spindle cells, with often invasion to the surrounding bladder muscular wall, and the presence of numerous multinucleated, osteoclast-like giant cells, scattered throughout the neoplasia.

Here we report a unique case of urinary bladder leiomyosarcoma with osteoclast-like multinucleated giant cells (OGCs). These cells, confounding the morphological aspect, indeed showed an immunohistochemical phenotype of non-neoplastic origin (most likely a histiocyte/macrophage differentiation). We feel that the presence of the OGCs within this tumor is reactive. Nevertheless, more research is necessary to understand the role of OGCs in urinary bladder tumors and leiomyosarcoma, in paticular.