Chronic hypersensitivity pneumonitis: CT features comparison with pathologic evidence of fibrosis and survival

To retrospectively compare in patients with chronic hypersensitivity pneumonitis (HP) the computed tomographic (CT) imaging features suggestive of fibrosis with pathologic evidence of fibrosis at surgical lung biopsy and to compare a usual interstitial pneumonia (UIP) pattern at CT with survival.

Institutional review board approval and informed consent were obtained for this study, which was HIPAA compliant. Twenty-six patients (15 women, 11 men; age range, 37-76 years) with chronic HP had their surgical lung biopsy results reviewed by two pathologists for the presence of fibrosis. Two radiologists systematically reviewed the CT scans. The two radiologists were blinded to all clinical information, including pathologic diagnosis, patient information, and outcomes. The combination of a subpleural reticular pattern and lower zone predominance was considered a UIP pattern. CT findings were compared with the histopathologic presence of fibrosis, physiologic parameters, symptoms, and survival. The chi(2) or Fisher exact test (each two-tailed) was used to compare nominal and ordinal variables. A t test (with unequal variances) was used to compare continuous variables. The log-rank procedure was used to compare Kaplan-Meier survival curves.

Fifteen patients had fibrotic HP at biopsy, and 11 had nonfibrotic HP. Patients with fibrotic HP had more extensive reticular pattern and were more likely to have traction bronchiectasis, honeycombing, and a UIP pattern than those with nonfibrotic HP (P = .015, P = .007, P = .007, respectively). Although the presence of histologic fibrosis was associated with decreased survival (P = .003), the CT features were not associated with decreased survival.

CT findings of extensive reticular pattern, traction bronchiectasis, and honeycombing are closely related to the presence of histologic fibrosis in chronic HP.