Hypersensitivity pneumopathies: x-ray computed tomographic aspects

Chest radiographs and computed tomographic scans obtained from nineteen patients with hypersensitivity pneumonitis were reviewed retrospectively. Thirteen of them had a subacute form. Six of them had a chronic form. In subacute forms, CT scans were normal in two patients. In the 11 other cases, CT findings were ground glass attenuation (n = 10), nodules (n = 7) and linear opacities (n = 5). Ground glass attenuation was diffuse or patchy. Two patterns are quite suggestive of hypersensitivity pneumonitis: the association of micronodules and ground glass attenuation and the presence of hyperlucent secondary lobules within the ground glass. After cessation of exposure, CT showed a return to normal or improvement. Ground glass opacities, nodules and also linear opacities disappeared. CT scans were always abnormal in chronic forms. CT findings were linear opacities (n = 6), ground glass attenuation (n = 4), micronodules (n = 2) and cysts (n = 3).