BRONCHIOLITIS IN CHRONIC PIGEON-BREEDERS DISEASE - MORPHOLOGIC EVIDENCE OF A SPECTRUM OF SMALL AIRWAY LESIONS IN HYPERSENSITIVITY PNEUMONITIS INDUCED BY AVIAN ANTIGENS

We analyzed 36 open lung biopsy specimens from patients with chronic p igeon breeder's disease (PBD) to assess bronchiolar involvement and it s relationship to the parenchymal pathologic abnormalities. Likewise, 21 biopsy specimens obtained from patients with usual interstitial pne umonia (UIP) were also examined. The bronchiolar abnormalities were sc ored by the method of Wright et al using a panel of photographs. In ad dition, the severity of lung fibrosis was evaluated in all samples and expressed as percentage in multiples of ten. A variable degree of epi thelial cell metaplasia, bronchiolar inflammation and fibrosis, smooth muscle hypertrophy, extrinsic small airways nan owing, and intralumin al macrophages was observed in both diseases, Occasionally, hyperplasi a of lymphoid follicles was also present. Bronchiolar changes were pro portional in type and severity to the parenchymal damage. Spearman's n onparametric correlation between fibrosis in parenchyma and fibrosis i n membranous bronchiole for the complete group (including patients wit h UIP and with PBD) showed a moderate but significant association (R=0 .51; p<0.01). A significant association was also demonstrated when the score for bronchiolar fibrosis and inflammation was evaluated in rela tion to lung fibrosis divided in high degree (>50%) and low degree (<5 0%), respectively. In the case of patients with PBD, the correlation b etween bronchiolar and parenchymatous fibrosis was of 0.33 (p<0.05). I n general, bronchiolar fibrosis was less severe and inflammation more severe in PBD lungs compared with patients with UIP. Fibrosis in membr anous bronchioles correlated with increased mortality in the complete group of patients, but the impact on mortality disappeared after corre cting for overall fibrosis in the biopsy sample, Our findings demonstr ate that a spectrum of bronchiolar lesions is usually observed in chro nic PBD lungs, although the predominant pattern is similar to that fou nd in the surrounding parenchyma, suggesting that the damage occurs in parallel.