IgG4-related disease (IgG4-RD) is a systemic fibro-inflammatory disorder that can affect multiple organs, but involvement of the prostate is rare. Most reported cases of IgG4-related prostatitis are associated with multiorgan disease and present with lower urinary tract symptoms (LUTS). Herein, we present a rare case of IgG4-related prostatitis, which was detected by whole-body diffusion-weighted imaging with background body signal suppression (DWIBS) and was pathologically diagnosed by MRI-fusion target biopsy, accompanied by IgG4-related dacryoadenitis/sialadenitis and multiple lymphadenopathies. Oral prednisolone relieved symptoms including general malaise, weight loss, and LUTS, with decreases in serum IgG4 levels. At the same time, DWIBS showed a remarkable signal reduction in the prostate and other involved organs. The present case suggests the usefulness of DWIBS in detecting and monitoring IgG4-RD including IgG4-related prostatitis.
Cureus. 2026 Feb 18*** epublish ***
Hajime Kido, Terumi Kamisawa, Keigo Setoguchi, Shin-Ichiro Horiguchi, Fumitaka Koga
Department of Urology, Tokyo Metropolitan Cancer and Infectious Diseases Center Komagome Hospital, Tokyo, JPN., Department of Gastroenterology, Tokyo Metropolitan Cancer and Infectious Diseases Center, Komagome Hospital, Tokyo, JPN., Department of Rheumatology, Komagome Hospital, Tokyo, JPN., Department of Pathology, Tokyo Metropolitan Cancer and Infectious Diseases Center, Komagome Hospital, Tokyo, JPN., Department of Urology, Tokyo Metropolitan Cancer and Infectious Diseases Center, Komagome Hospital, Tokyo, JPN.