INTRODUCTION: Non-muscle-invasive bladder cancer (NMIBC) is usually effectively 
treated with transurethral resection (TUR), most often followed by intravesical 
instillation of bacillus Calmette-Guérin (BCG) or intravesical chemotherapy. 
Although the precise mechanism of BCG immunotherapy is still unclear, a local 
immune response is presumed. However, a number of severe side effects and 
complications are related to intravesical immunotherapy.
AIM: Aim of this report is to present rare case of the renal granulomatous 
disease in a patient previously treated with intravesical instillation of BCG 
immunotherapy, following TURBT. In addition, we performed review of previously 
reported cases of renal granulomas following intravesical BCG immunotherapy.
CASE REPORT: A 79-year-old man was presented to Urology Clinic due to clinically 
verified tumor of the urinary bladder. After transurethral resection of bladder 
tumor, histopathological analysis revealed the diagnosis of papillary urothelial 
high-grade pT1 carcinoma. Intravesical BCG immunotherapy was initiated, 
according to protocol currently used in our institution. Upon completion of 
therapy with BCG, we re-examined the patient and, using ultrasound, found a 
change in the right kidney, resembling moth bites not seen on CT scan before 
TURBT. Additionally, CT-guided core-needle biopsy of the affected kidney was 
performed, and the specimen was sent for histopathological analysis, which 
revealed chronic necrotizing granulomatous inflammation. Antituberculotic 
therapy was initiated for 6 months. Upon completion of antituberculotic therapy, 
control CT-scan was performed at follow-up, indicating regression of changes on 
the right kidney.
CONCLUSION: This case report emphasizes the importance of consistent 
implementation of follow-up protocol and the identification of lesions during 
the asymptomatic period and enables the proper treatment of the disease. To 
reduce the incidence of adverse effects of BCG treatment for bladder tumors, an 
individualized approach is needed.