Advanced renal tuberculosis due to misdiagnosis as recurrent urinary tract infection: A case report.

Renal tuberculosis (RTB) lesions often initially localize to a specific part of the kidney, presenting with minimal clinical symptoms and a very slow disease progression, which makes the condition highly susceptible to misdiagnosis. We report an instructive case from the Second Affiliated Hospital of Zhejiang University School of Medicine, where a patient was ultimately diagnosed with advanced RTB after a 20-year diagnostic odyssey. The patient exhibited atypical clinical symptoms and was repeatedly diagnosed with recurrent urinary tract infection (UTI). Initial urinalysis revealed microscopic hematuria (52 RBCs/μL), pyuria (615 WBCs/μL), and 1 + proteinuria (0.7 g/L). A urine culture tested positive for Escherichia coli. Ultrasound imaging indicated a right renal calculus, and intravenous pyelography demonstrated significantly diminished right renal function. Suspicion for RTB was raised by CT findings and a positive tuberculosis infection T-cell spot (T-SPOT.TB) test. Acid-fast bacilli were consistently detected in two consecutive urine sediment examinations. The diagnosis was ultimately confirmed through metagenomic next-generation sequencing (mNGS) and postoperative pathological examination. This case underscores that the early diagnosis of RTB is challenging and requires a high index of clinical suspicion, comprehensive analysis of manifestations, and the strategic integration of modern diagnostic tools.