Urothelial carcinoma (clear cell variant) diagnosed with useful immunohistochemistry stain

The case is reported of urothelial carcinoma (clear cell variant) that was diagnosed with useful immunohistochemistry stain. A 70‐year‐old man, who had undergone left radical nephrectomy for renal cell carcinoma in August 2003 and partial lobectomy for pulmonary metastasis in May 2005, complained of hematuria in June 2005. On evaluation, a papillary pedunculated tumor was detected in the left wall of the urinary bladder. A transurethral resection of the bladder tumor (TUR‐Bt) was performed in July 2005. The pathological diagnosis was difficult due to diffuse clear cell appearance. Immunohistochemistry stain showed urothelial carcinoma, not metastasis of the renal cell carcinoma. Finally it was diagnosed as urothelial carcinoma clear cell variant. Urothelial carcinoma has many variants that show a variety of appearances and characteristics. These should be well known before medical therapy is initiated.