RESUMEN
Immunoglobulin G4 (IgG4)-related sclerosing disease is a systemic inflammatory syndrome, and an understanding of its characteristics is currently evolving. IgG4-related cholecystitis is a manifestation of IgG4-related sclerosing disease in the gallbladder. This case report describes the clinical, radiographic, and histopathological findings in a young male patient who presented with a synchronous mass in the gallbladder. Serum levels of IgG4 and the IgG4/IgG ratio were normal, and there was no associated autoimmune pancreatitis. Therefore, establishing a preoperative diagnosis of IgG4-related cholecystitis was very difficult, and a differential diagnosis of gallbladder cancer infiltrating the liver was suggested. Postoperative histopathological examination established a diagnosis of IgG4-related cholecystitis definitively. A preoperative diagnosis of IgG4-related cholecystitis, although possible, would have been highly challenging in this case. It is difficult to establish whether surgical intervention is necessary in IgG4-related cholecystitis. Because malignant tumors are frequently suspected with this clinical presentation, surgical intervention should be undertaken only after due deliberation.