Skin lesions in a patient with IgG4-related disease

Summary IgG4-related disease (IgG4-RD) is a newly recognized condition that is characterized by raised levels of serum IgG4, tissue infiltration of IgG4-positive plasma cells and presence of fibrosis. It affects multiple organs, including the pancreas, bile duct, and lacrimal and salivary glands. Skin lesions have rarely been reported, and those that have were described as distributed mainly in the head and neck region. We report a case of IgG4-RD with autoimmune pancreatitis and skin lesions on the trunk and limbs. The skin lesions responded well to oral prednisolone (PSL); however, tapering of PSL to 5 mg/day resulted in recurrence. At present, the skin disease is well controlled at a dose of 7 mg/day. Interestingly, IgG4 levels fluctuated with changes in the PSL dose but did not coincide with the severity of the skin disease, implying that the raised levels of IgG4 did not directly influence the skin symptoms.