Morphology in chronic HP is characterized by bronchiolocentric mononuclear inflammation, poorly formed granulomas and variable degree of fibrosis. However, recent findings suggest that this disease may present different pathologic patterns. In this study we evaluated the clinical behavior and survival of patients with pigeon breeder's disease according to the pathologic pattern. One-hundred ten biopsies were classified as "typical" (n = 58), non-specific interstitial pneumonia (NSIP)-pattern (n = 22), usual interstitial pneumonia (UIP)-like (n = 10), mixed pattern (n = 9), organizing pneumonia (OP)-pattern (n = 3), airway-centered interstitial fibrosis (ACIF)-pattern (n = 3), and non-classified (n = 5). Clinical features and survival were compared between patients with "typical", NSIP, and UIP patterns. There were no statistical differences between the groups in age, gender, time of symptoms, smoking, clubbing, and PaO(2). By the one-way ANOVA test we found differences in the percent of lymphocytes in bronchoalveolar lavage (BAL; p < 0.002) and in the forced vital capacity (p < 0.05) between the 3 groups. After Bonferroni correction the difference in BAL lymphocytes remained significant among the UIP-like and the typical pattern (36.1 ± 22.9 versus 64.6 ± 20.9, p = 0.001). UIP-like patients exhibited the worst survival rate (HR: 4.19; 95% CI: 1.66-14.47; p < 0.004) while NSIP-like pattern showed the best survival (HR: 0.18; 95% CI: 0.04-0.82; p < 0.03). Multivariate Cox regression analysis revealed that patients with a UIP-like pattern retained a significantly worse survival (HR: 3.4 (IC 95%: 1.15-10.29; p < 0.03), and mortality for the NSIP group was best and approached statistical significance (p = 0.07). These findings demonstrate that a variety of histopathologic and imaging patterns are seen in PBD, and the presence of a UIP-like pattern confers the worst prognosis.
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