Clinicopathological features of localized-type IgG4-related cholecystitis: a nationwide multicenter study in Japan.

BACKGROUND

Immunoglobulin G4 (IgG4)-related cholecystitis represents gallbladder involvement in IgG4-related disease (IgG4-RD). However, localized-type IgG4-related cholecystitis is rare and remains poorly characterized. We conducted a nationwide, multicenter study to clarify the clinicopathological features of localized-type IgG4-related cholecystitis in Japan.

METHODS

We collected clinical information, imaging data, and tissue slides from suspected cases of IgG4-related cholecystitis for central review, and evaluated their clinicopathological features.

RESULTS

Fifteen patients were diagnosed with localized-type IgG4-related cholecystitis. The incidence of localized-type IgG4-related cholecystitis was 0.59% (15/2560) among all IgG4-related gastroenterological diseases across 30 institutions. The median age was 62 years (range, 54-70 years), and 10 patients were men. Elevated serum IgG4 levels and other IgG4-RD lesions were observed in all 15 patients. Imaging findings demonstrated subepithelial lesions (SELs) of the gallbladder in all patients, and cystic lesions within SELs suggestive of adenomyomatosis (ADM) in nine patients. Among the 11 patients with available histopathological analyses, two distinct types of mass-forming lesions (inflammatory pseudotumors) characterized by storiform fibrosis and obliterative phlebitis were identified: ADM-type in six cases and mural hypertrophy-type in three cases. Eleven patients underwent surgery and four received glucocorticoids therapy. Within 2-4 weeks of initiating glucocorticoid therapy, complete resolution was achieved in one patient, and partial improvement in three patients.

CONCLUSION

Localized-type IgG4-related cholecystitis is characterized by imaging findings of SELs. It shares histopathological features of IgG4-RD, and often has unique lesions centered around ADM. It responds to glucocorticoid therapy.