[Chest high resolution CT features of extrinsic allergic alveolitis and its diagnostic value].

OBJECTIVE: To summarize the chest high-resolution CT (HRCT) features of the patients with extrinsic allergic alveolitis (EAA).

METHODS: We analyzed the images of chest HRCT of 34 patients diagnosed as EAA at our hospital from February 2001 to August 2009.

RESULTS: All patients had a history of environmental exposure. The duration of intermittent or continuous antigen exposure was from 3 months to 13 years. Two patients showed acute clinical manifestations. There were 22 sub-acute and 10 chronic cases. Acute EAA was characterized by ground-glass opacities, air trapping and/or mosaic sign on HRCT. The HRCT features of subacute EAA included patchy ground-glass opacities with mosaic sign (n = 11, 50.0%) and diffusely distributed centrilobular nodules (n = 7, 31.8%) with mosaic sign (n = 4, 18.2%). All patients with chronic EAA had reticular and honeycombing lesions on HRCT. There were 3 cases with ground-glass opacities, 3 with mosaic sign, and 3 with centrilobular nodules.

CONCLUSION: The typical findings of chest HRCT are helpful for making a diagnosis and differential diagnosis of EAA.