CYR61 (CCN1) is a metastatic biomarker of gastric cardia adenocarcinoma.

Renal pelvis epidermoid cysts are extremely rare and are often misdiagnosed as stones or tumors. Only one previous case has been treated using the percutaneous approach. A 67-year-old female with diabetes who was receiving empagliflozin presented with imaging findings suggestive of a staghorn calculus. During percutaneous nephrolithotomy, whitish keratinous material was found in the renal pelvis, along with a small obstructing stone. All material was evacuated through the Amplatz sheath. Urine culture was negative. Histopathological examination confirmed an epidermoid cyst. A postoperative computed tomography scan at 1 month showed complete resolution. Epidermoid cysts can radiologically mimic staghorn calculi. A fungal ball was initially suspected because of diabetes and sodium-glucose cotransporter 2 inhibitor therapy, but radiopacity, negative culture, and histopathological findings ruled this out. Percutaneous nephrolithotomy served as both a diagnostic and therapeutic procedure while preserving renal function. Renal pelvis epidermoid cysts should be considered in the differential diagnosis of opaque pelvic lesions. Percutaneous nephrolithotomy is a minimally invasive, kidney-preserving treatment that can be performed as a renal-sparing procedure.