Chronic Hypersensitivity Pneumonitis With a Usual Interstitial Pneumonia-Like Pattern Correlation Between Histopathologic and Clinical Findings

BACKGROUND: Hypersensitivity pneumonitis (HP) is an interstitial lung disease caused by the inhalation of environmental antigens. The relationship between clinical, radiologic, and histopathologic findings of chronic HP remains unclear. METHODS: Sixteen patients with proven chronic bird-related HP with a usual interstitial pneumonia-like pattern were analyzed retrospectively. Histopathologic findings were semi-quantitatively assessed and compared with clinical and radiologic findings. We also evaluated the histopathologic findings affecting prognosis. RESULTS: The extent of centrilobular fibrosis was negatively correlated with Pao(2) (r = -0.55, P = .03). The extent of bridging fibrosis was positively correlated with the ratio of maximal expiratory flow at 50% of forced vital capacity to that at 25% (r = 0.60, P = .02). Patients with a greater extent of fibroblastic foci (FF) had more radiologic reticulation (P = .01), honeycombing (P = .01), and traction bronchiectasis (P = .02), and had significantly shorter survival time (P = .01) than patients with a lesser extent of FF. Multivariate analysis showed that the extent of FF was a significant prognostic factor (hazard ratio, 2.36; 95% confidence interval, 1.02-5.48; P = .04). CONCLUSIONS: Our findings demonstrated that the extent of FF was significantly associated with reticulation, honeycombing, and traction bronchiectasis on high-resolution CT scanning. Moreover, the extent of FF could be a useful predictor of mortality in chronic HP with a usual interstitial pneumonia-like pattern.