Correlation Between the Natural Course and Magnetic Resonance Imaging Features of Bacillus Calmette-Guérin-Related Granulomatous Prostatitis in Patients With Bladder Cancer.

Authors

Ki Choon Sim, Deuk Jae Sung, Na Yeon Han, Yeo Eun Han, Beom Jin Park, Min Ju Kim

Published in

Journal of Korean medical science. Volume 41. Issue 26. Pages e178. Jul 06, 2026. Epub Jul 06, 2026.

Abstract

To evaluate magnetic resonance imaging features and the natural course of granulomatous prostatitis after intravesical Bacillus Calmette-Guérin therapy in patients with bladder cancer.
Using a radiologic report keyword search program, data were collected from magnetic resonance images between March 2018 and August 2023. A total of 241 baseline or follow-up magnetic resonance images of 64 patients with pathologically or clinically confirmed Bacillus Calmette-Guérin-related granulomatous prostatitis were retrospectively included. We investigated intravesical Bacillus Calmette-Guérin history, lesion size changes, and serum prostate-specific antigen changes through a chart review. Lesion imaging features were assessed on T1-. T2-, diffusion-, and contrast-enhanced T1-weighted images and classified based on enhancement degree and presence of diffusion restriction.
The completely improved group (n = 12), incompletely improved group (n = 26), and recurrent inflammation group (n = 13) were identified according to temporal magnetic resonance imaging changes of granulomatous prostatitis. Patients who underwent radical cystectomy or were lost to follow-up were excluded due to unknown outcomes (n = 13). Among 64 patients, subtle increased T1 signal intensity with granulomatous inflammation was observed in 57 (89.1%). The baseline prostate-specific antigen level in the recurrent inflammation group was 2.00 ± 1.26 ng/mL, which was higher than the 1.0-1.1 ng/mL levels in the other groups (P = 0.050). Even if the lesion completely improved on magnetic resonance imaging, the serum prostate-specific antigen level increased by approximately 2.0 times compared to the baseline level. Lesion peak size (26.0 ± 15.0 mm) in the incompletely improving group was significantly larger than that in the other groups (14.8 ± 5.8 and 17.0 ± 9.1 mm) (P = 0.006). Among the 77 initial magnetic resonance images, type A (n = 30, strong enhancement and diffusion restriction), type B (n = 25, rim enhancement with diffusion restriction), and mixed type (n = 19) were the most common. In the last 50 magnetic resonance images, type C (n = 34; no enhancement or diffusion restriction) was predominant.
In patients who underwent intravesical Bacillus Calmette-Guérin therapy, bladder magnetic resonance imaging frequently revealed subtle T1-hyperintense lesion in the prostate with diffuse or rim-like enhancement accompanied by markedly restricted diffusion, which is highly suggestive of Bacillus Calmette-Guérin-related granulomatous prostatitis and tends to spontaneously regress on follow-up imaging. Even with radiological improvement, prostate-specific antigen levels may remain elevated and should not be mistaken for malignancy.

PMID:
42411237
Bibliographic data and abstract were imported from PubMed on 07 Jul 2026.

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