Renal epidermoid cyst mimicking renal tuberculous abscess: a case report.

Renal epidermoid cysts (RECs) are exceedingly rare benign cystic lesions, with only 15 histologically confirmed cases reported worldwide to date. Due to their non-specific clinical and radiological features, they are often misdiagnosed preoperatively as infectious or neoplastic conditions. Here, we report a 25-year-old man in whom a complex renal cyst was incidentally identified during a routine health examination. Retrospectively, the patient reported mild urinary frequency and low-grade fever. Imaging suggested a non-enhancing heterogeneous cyst in the lower pole of the right kidney. Laparoscopic partial nephrectomy was performed, revealing abundant yellow-white caseating material intraoperatively, prompting empirical anti-tuberculosis therapy in the context of regional endemicity. However, histopathological analysis confirmed a diagnosis of RECs, and anti-tuberculous treatment was subsequently withdrawn. On postoperative day 5, the patient developed gross hematuria due to a renal artery pseudoaneurysm, which was successfully managed with selective arterial embolization. This case highlights the diagnostic challenges posed by atypical cystic renal lesions and underscores the importance of integrating imaging, intraoperative findings, and histopathology. Including RECs in the differential diagnosis may prevent unnecessary antituberculous therapy and overtreatment.