Osteoclast-rich undifferentiated carcinoma of the bladder and the diagnostic usefulness of immunohistochemistry. A case report

Osteoclast-rich undifferentiated carcinoma (ORUC) of the urinary tract is a rare variant of urothelial carcinoma, first described in 1985 by Kitazawa et al. It has a worse prognosis compared to other histological variants of invasive urothelial carcinoma and its diagnosis may prove challenging due to the variability in its immunohistochemical profile. We present a case of ORUC in which GATA3 immunostaining was a useful diagnostic tool.