Inflammatory pseudotumor of the lung with pleural thickening treated with corticosteroids.

A 56-year-old man was admitted to Hiroshima University Hospital in 1987 because of radiographic evidence of pulmonary abnormalities, fever, and anorexia. A radiograph of the chest showed bilateral thickening of the pleura in the middle field. A CT scan of the chest disclosed remarkable thickening of the pleura and a tumorous lesion, 2 3 3.5 cm in diameter, with a low density area in the right lung (Fig 1). Because the etiology was unknown except in the lungs, an exploratory thoracotomy was performed. A microscopic examination of the resected specimen disclosed that the tumor was composed of a proliferation of fibroblasts and an infiltration of plasma cells, macrophages, and lymphocytes accompanied by a local accumulation of hyaline collagen layers (Fig 2). Because a low-grade fever and increased levels of C-reactive protein remained after the operation, 20 mg/d prednisolone was administered. After 2 weeks of corticosteroid treatment, the symptoms improved, and the dose of prednisolone was gradually tapered. No recurrence was observed after 10 years of follow-up. Inflammatory pseudotumors are rare diseases that generally occurs in the lung. To our knowledge, there is only one report describing an inflammatory pseudotumor presenting pleural thickening that showed spontaneous regression.1 Ishida et al2 reported that, intraoperatively, the parietal pleura was involved in three of seven patients with inflammatory pseudotumors. In our patient, although the histologic examination of the resected pleura revealed remarkable fibrosis without evidence of inflammatory pseudotumor involvement, adjacency between the tumor and the pleural thickening suggested a relationship of these lesions. After complete resection of the tumor, the symptoms remained, suggesting an active lesion in the remaining thickening pleura. The diagnosis of inflammatory pseudotumor is not commonly made before resection, and complete resection leads to an excellent prognosis.3 Unresected or recurred cases in patients were reportedly treated with corticosteroids, which resulted in a decrease in size or complete regression.4,5 Before corticosteroid treatment, our patient was treated with nonsteroidal anti-inflammatory drugs, which were not effective. These observations suggest that corticosteroids may be an option in treating inflammatory pseudotumors.