A Case of IgG4-related Retroperitoneal Fibrosis and Hypophysitis with Antecedent Respiratory Disease followed by Spontaneous Remission and Recurrence.

A 65-year-old man presented with apparent bronchopneumonia. After treatment with antibiotics, he showed eosinophilia. Computed tomography (CT) imaging revealed bilateral consolidation, ground-glass opacities with nodular consolidations and pleural effusion. Lung biopsy showed organizing pneumonia with lymphoplasmacytic infiltration in alveolar septa and in thickened pleura and interlobular septa. All pulmonary abnormalities spontaneously went into remission within 12-months. At 73 years old, a follow-up CT scan revealed small nodules in both lungs and the review of head CT scan showed thickening of pituitary stalk in studying prolonged headache. Two years later, he visited hospital complaining severe edema on the lower extremities with high serum IgG4 186mg/dL. Whole-body CT scan showed retroperitoneal mass surrounding aortic bifurcation and compressing inferior vena cava, pituitary stalk thickening and gland swelling, and enlarged pulmonary nodules. Anterior pituitary stimulation tests showed central hypothyroidism, central hypogonadism and adult growth hormone deficiency with partial primary hypoadrenocorticism. Retroperitoneal mass biopsy showed storiform fibrosis and obliterative phlebitis with marked lymphoplasmacytic infiltration with moderate IgG4-positivity. Immunostaining of the former lung specimen revealed dense interstitial infiltration of IgG4-positive cells. These findings indicated metachronous development of IgG4-related disease in lung, hypophysis and retroperitoneum, according to the recent comprehensive diagnostic criteria of IgG4-related disease. Glucocorticoid therapy ameliorated edema, on the other hand, unmasked partial diabetes insipidus at the initial dose of the treatment. Hypothyroidism and retroperitoneal mass regressed at 6-months of the treatment. This case warns us that long-term follow-up from prodromal to remission is necessary in the treatment of IgG4-related disease.