A non-healing tract with a hidden enemy: Navigating a diagnostic dilemma in a persistent post-PCNL Nephrocutaneous fistula

Background: Nephrocutaneous fistula is an exceptionally rare and challenging complication following percutaneous nephrolithotomy (PCNL). Even more uncommon is its occurrence as a manifestation of renal tuberculosis—a stealthy infection that often eludes diagnosis, especially when systemic symptoms are absent and microbiological tests fail to confirm the disease. This diagnostic uncertainty can delay treatment, making timely recognition critical in managing such unusual presentations. Case Presentation: We report the case of a 67-year-old diabetic male with a history of recurrent urolithiasis who underwent left-sided percutaneous nephrolithotomy (PCNL) with Double-J stenting uneventfully, achieving complete stone clearance. The stent was subsequently removed. Ten weeks later, the patient presented with complaints of persistent purulent discharge and urine leak from a non-healing wound at the prior nephrostomy site in the left lumbar region. Laboratory evaluation revealed elevated inflammatory markers, including a markedly raised erythrocyte sedimentation rate (ESR) and high-sensitivity C-reactive protein (Hs-CRP). Imaging studies demonstrated a fistulous tract extending from the upper calyx to the subcutaneous tissue, accompanied by multiple soft tissue collections. Despite negative results for pus culture and Ziehl-Neelsen staining, histopathological examination of the fistulous tract biopsy revealed granulomatous inflammation with caseous necrosis and Langhans-type giant cells—findings highly suggestive of renal tuberculosis. Given the clinical and histopathological suspicion, the patient was initiated on empirical anti-tubercular therapy (ATT). Remarkably, the fistula healed completely with six months of ATT, without the need for any further surgical intervention Conclusion: This case underscores the exceptional rarity of renal tuberculosis manifesting as a persistent nephrocutaneous fistula several weeks after an uneventful PCNL, particularly in the absence of systemic symptoms or microbiological confirmation. This case illustrates the clinical dilemma in managing non-healing post-PCNL tracts and reinforces the need to consider renal tuberculosis in the differential diagnosis, especially in endemic regions. Importantly, it demonstrates that empirical anti-tubercular therapy initiated based on suggestive histopathology and clinical judgement, can achieve complete resolution of the Nephrocutaneous fistula without further surgical intervention.