Hybrid eclipse: a case of isolated renal tuberculosis with an unusual infectious–inflammatory–neoplastic triad

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Isolated renal tuberculosis (RTB) is a rare extrapulmonary manifestation of tuberculosis that often mimics common urinary tract infections, resulting in delayed diagnosis and complications. We report an exceptionally rare case of isolated RTB presenting with a spectrum of destructive sequelae-including a perinephric abscess with a nephrocutaneous fistula, renal replacement lipomatosis (RRL), and synchronous clear cell renal cell carcinoma (RCC) within a single kidney. We report the case of a 77-year-old diabetic man who presented with left loin pain and chronic lumbar sinus discharge. Multiphase computed tomography (CT) revealed an enlarged, distorted kidney with extensive sinus and perinephric fat proliferation consistent with RRL; a hyperenhancing superior-pole mass suggestive of RCC; calyceal distortion and infundibular stenosis suspicious for RTB; and a perinephric abscess with a cutaneous fistula. Radical nephrectomy was performed, and histopathological examination confirmed renal tuberculosis and its associated complications. Subsequent antitubercular therapy (ATT) resulted in stable clinical and functional outcomes. To the best of our knowledge, this is the first reported case demonstrating this constellation of infectious-inflammatory-neoplastic pathologies within a single kidney. This case highlights the indolent yet destructive nature of isolated RTB and emphasizes the role of early imaging and histopathology for timely diagnosis, prevention of serious complications, and an improved prognosis.