Inflammatory pseudotumors in multiple organs associated with elevated serum IgG4 level: recovery by only a small replacement dose of steroid.

A 62-year-old man developed a fever, fatigue, anorexia and arthralgia. Central hypocorticoidism and central hypothyroidism were observed, and a low serum antidiuretic hormon level without symptoms of diabetes insipidus, as well. Images showed swelling of pituitary stalk, mediastinal and hilar lymphnodes and pancreas, pulmonary infiltrates and retroperitoneal mass. Serum CRP level was 20.6 mg/dL, and IgG4 level was 292 mg/dL. Lung biopsy revealed pseudotumor containing IgG4-positive plasmacytes, and obliterative vasculitis both in arterioles and venules. These features were similar to those of reported IgG4-related autoimmune disease. However, replacement steroid therapy for hypocorticoidism brought about almost complete recovery except that diabetes insipidus got apparent. This is the first report on the efficacy of only a small dose of steroid, and on features of pituitary stalk involvement and central hypocorcicoidism.