[Case of multiple nodular lesions of bilateral kidneys with IgG4-related systemic disease]

A 59-year-old woman was admitted to our hospital because of a pancreatic mass lesion. Serum gamma-globulin and IgG4 levels were elevated to 2.2 g/dL and 1,310 mg/dL, respectively. Computed tomography examination revealed multiple low-density areas without enhancement by contrast in the pancreatic body and bilateral kidneys. Endoscopic retrograde cholangiopancreatography images demonstrated diffuse narrowing of the main pancreatic duct with an irregular wall from the body to the tail of the pancreas. Positron emission tomography examination revealed intense 18F-fluorodeoxyglucose uptake by the pancreas and kidneys. Accordingly, the patient was diagnosed as having IgG4-related autoimmune pancreatitis. In addition, the findings of a renal tissue specimen obtained by biopsy demonstrated IgG4-positive plasma cell infiltration in both abnormal mass lesions and normal regions by imaging, leading to the final diagnosis of IgG4-related sclerotic disease. The patient was treated with prednisolone (30 mg/day), and the size of the pancreatic and renal lesions markedly decreased four weeks later. We report here a rare case of IgG4-related autoimmune pancreatitis with multiple renal lesions, which were confirmed by renal biopsy.