Pulmonary inflammatory pseudotumor: Radiologic features

PURPOSE: To define the radiologic features of pulmonary inflammatory pseudotumor. MATERIALS AND METHODS: Between 1966 and 1994, 61 cases of pulmonary inflammatory pseudotumor involved 36 male and 25 female patients (age range, 17 months to 61 years; mean, 28 years). Clinical presentation, pathologic features, and radiologic findings were noted. RESULTS: At radiography, 52 patients had solitary peripheral nodules or masses, and extraparenchymal involvement-including hilar, mediastinal, and airway invasion-was found in 11. At computed tomography, 12 lesions were of heterogeneous attenuation and five, homogeneous. At T1-weighted magnetic resonance imaging, five lesions had intermediate signal intensity; of two lesions studied with T2-weighted imaging, two had high signal intensity; and the one lesion studied with gadolinium-enhanced imaging had diffuse enhancement. CONCLUSION: Pulmonary inflammatory pseudotumor was typically a solitary, peripheral, sharply circumscribed mass with an anatomic bias for the lower lobes. Local invasion and primary involvement of the mediastinum and hilar structures were unusual manifestations.