Renal oncocytoma: an incidental case and a diagnostic enigma—a case report

Renal oncocytoma (RO) is a benign parenchymal tumour of the kidney that arises from the distal renal tubules. Renal oncocytoma is usually small in size; however, giant lesions are uncommon. The tumour is generally asymptomatic, often diagnosed incidentally, and is considered renal cell carcinoma (RCC) pre-operatively. Diagnosis, however, is challenging on CT-imaging; nonetheless, biopsy can yield a promising diagnosis. This report presents the case of a 35-year-old asymptomatic male, patient, who presented to the oncology out-patient department of Dr. Ziauddin Hospital, Karachi on 15th January 2025 with a right sided renal mass on his abdominal computed tomography that was discovered incidentally while he was undergoing diagnostic imaging for appendectomy. The patient underwent an elective right radical nephrectomy, and post-operative biopsy confirmed the diagnosis of renal oncocytoma. He presented for oncological consultation. Considering the disease course, tumour characteristics, clinical presentation, and prognosis in accordance with the current guidelines and literature, close follow-up was advised. Keywords: Renal oncocytoma, Nephrectomy, Case report, Renal cell carcinoma.