Renal Cell Carcinoma With Fibromyomatous Stroma: A New Case.

In the 2016 World Health Organization (WHO) classification of renal tumors, renal cell carcinoma with fibromyomatous stroma (RCC FMS) (formerly RCC with leiomyomatous or smooth muscle stroma) was classified as an emerging or provisional entity of renal cell carcinoma (RCC). We report a rare case of RCC FMS in a 62-year-old male patient with hypertension, type II diabetes mellitus, and early chronic kidney disease. He was referred to the Department of Urology for an incidental finding of a 2-cm-long left renal nodule on a routine abdominal ultrasound. A laparoscopic right partial nephrectomy was performed. Histopathology and immunohistochemistry studies confirm the diagnosis of RCC FMS. The purpose of this work is to review and discuss newly acquired data and evidence on the clinical, pathological, immunohistochemical, molecular, and prognostic aspects of this unusual entity in the hopes of assisting pathologists in accurate diagnosis.