Tubulocystic renal cell carcinoma in the left kidney: a case report

INTRODUCTION: Tubulocystic renal carcinoma is a rare tumor and has been recently recognized as a neoplastic entity. We report a case of tubulocystic renal carcinoma in the left kidney and present a review of relevant literature. CASE PRESENTATION: A 35-year-old Japanese woman visited our hospital with the chief complaint of left-sided back pain. Computed tomography revealed a hemorrhagic cyst (size, 7×8cm) in the upper pole of her left kidney. Approximately 3 years after the initial diagnosis, she complained of left-sided back pain again. Magnetic resonance imaging revealed an enlarged left renal cyst (size, 10×12cm) with a slightly enhanced cystic wall. The tumor was clinically diagnosed as a renal cell carcinoma in the cT2N0M0 stage, which arose from the cyst wall; therefore, left nephrectomy was performed. On histological examination, the tumor showed circumscribed proliferation with cystically dilated tubules. The tubules and cysts were lined by a single layer of flat, hobnail, and cuboidal cells. Immunohistochemical analysis revealed that the tumor cells were strongly positive for E-cadherin and P504S. CONCLUSIONS: Examination of more cases of tubulocystic renal carcinoma is required to better understand the biology of this tumor and to ascertain its prognosis.