Granulomatous Interstitial Nephritis Following Bacillus Calmette-Guérin (BCG) Therapy: A Case Report

Introduction: The development of renal granulomas is a rare complication following intravesical BCG therapy for urothelial carcinoma. This condition is associated with interstitial inflammation and fibrosis leading to impaired renal function. Renal granuloma formation may be linked to vesicoureteral reflux which is frequently observed following transurethral resection of bladder tumors, particularly when the tumor is situated close to the ureteral orifice. Case Description: We report a case of a 62-year-old man with high-grade non-invasive papillary urothelial carcinoma who underwent TURBT and received 2 cycles of intravesical BCG therapy. Following treatment, he developed a progressively rising serum creatinine from baseline of 1.1-1.2 mg/dl to to1.9 mg/dl with spot proteinuria of 1.1 g/g. Kidney biopsy showed extensive granulomatous interstitial nephritis with focal necrosis and approximately 40% fibrosis (Figures 1, 2). Discussion: This rare entity should be considered during BCG therapy especially if a rise in serum creatinine cannot be explained by urologic causes. Management is controversial and includes observation or treatment with antituberculous chemotherapy with or without corticosteroids.Figure 1. A. (H&E x40). This photomicrograph shows extensive patchy granulomas noted in the interstitium with scattered multinucleated giant cells, lymphocytes, plasma cells and histiocytes. There are two foci of necrosis present in the granulomas.B. (H&E x200). This photomicrograph shows a higher power view of the granulomas with inflammation.