[A Case of Chromophobe Renal Cell Carcinoma Producing Interleukin-6 with Stauffer Syndrome].

A 41-year-old male consulted a local doctor with fever and left flank pain. He was introduced to our hospital for a left renal mass detected by ultrasonography. Blood analysis revealed elevated white blood cell count, C-reactive protein, bilirubin and aspartate transaminase. Computed tomography demonstrated a left renal mass (expansive growth), which was 11 cm in maximum diameter and enhanced moderately at the corticomedullary phase. Neither distant metastasis, infectious findings nor hepatobiliary abnormalities were observed. The patient underwent laparoscopic radical nephrectomy with a clinical diagnosis of non-clear cell renal cell carcinoma cT2bN0M0 with Stauffer syndrome. The surgery required 186 minutes of insufflation, and estimated blood loss and specimen weight were 44 ml and 695 g, respectively. There were no complications. Histopathological diagnosis was chromophobe renal cell carcinoma-classic pattern (ChRCC-C), which was producing interleukin-6 in the tumor cytoplasm immunohistochemically. Postoperatively, there was early defervescence with complete resolution of the Stauffer syndrome. No relapse or liver dysfunction has occurred at 5 years after operation. To our knowledge, this is the first reported case in the literature of ChRCC accompanied by Stauffer syndrome.