Granulomatous prostatitis after bacille Calmette-Guérin instillation resembles prostate carcinoma: A case report and review of the literature

BACKGROUND: Bacille Calmette-Guérin (BCG) instillation is recommended in patients with non-muscle-invasive bladder cancer who have intermediate-risk and high-risk tumors. However, granulomatous prostatitis is a rare complication induced by BCG instillation, which can easily be misdiagnosed as prostate cancer. Here, we report a case of granulomatous prostatitis that resembled prostate cancer. CASE SUMMARY: A 64-year-old Chinese man with bladder cancer received BCG instillation. Three days later, he stopped BCG instillation and received anti-infective therapy due to the urinary tract infection. Three months after BCG restart, he had rising total prostate-specific antigen (PSA) (9.14 ng/mL) and decreasing free PSA/total PSA (0.09). T2-weighted images of magnetic resonance imaging (MRI) showed a 28 mm × 20 mm diffuse low signal abnormality in the right peripheral zone, which was markedly hyperintense on high b-value diffusion-weighted MRI and hypointense on apparent diffusion coefficient map images. Considering Prostate Imaging Reporting and Data System score of 5 and possibility of prostate cancer, a prostate biopsy was conducted. Histopathology showed typical features of granulomatous prostatitis. The nucleic acid test for tuberculosis was positive. He was finally diagnosed with BCG-induced granulomatous prostatitis. Thereafter, he stopped BCG instillation and received anti-tuberculosis treatment. During 10 mo follow-up, he had no evidence of tumor recurrence or symptoms of tuberculosis. CONCLUSION: Temporarily elevated PSA and high followed by low signal abnormality on diffusion-weighted MRI are important indicators of BCG-induced granulomatous prostatitis.