BRONCHIOLITIS OBLITERANS ORGANIZING PNEUMONIA-LIKE REACTIONS - A NONSPECIFIC RESPONSE OR AN ATYPICAL FORM OF REJECTION OR INFECTION IN LUNGALLOGRAFT RECIPIENTS

Bronchiolitis obliterans organizing pneumonia (BOOP) is a ubiquitous e ntity, known to occur either idiopathically or in association with var ious pulmonary disorders. Histologically, it is characterized by myxom atous connective tissue plugs present in the lumen of bronchioles with extension into the alveoli. Its significance in lung allograft recipi ents is not well documented. The authors reviewed all post-lung transp lant biopsies (565 transbronchial; 19 open), explanted lungs for retra nsplantation (six), and autopsies (38) from 115 patients. A total of 3 2 patients (18 females and 14 males) showed histological evidence of B OOP-like reactions (ie, Masson bodies in 44 transbronchial and seven o pen lung biopsies). The mean age was 47 years (range = 14 to 69 years) . Sixteen patients were recipients of single lungs, 14 received bilate ral single lungs, and two had heart and double-lung transplants. BOOP- like reactions (BOOP-LRs) occurred as early as day 5 and as late as da y 1,208 (40 months) posttransplantation. Twenty patients had one biops y showing BOOP-LR, of which three patients had resolving mild acute re jection, four had ongoing minimal acute rejection, seven had ongoing m ild acute rejection, one each had ongoing moderate and bronchiolar rej ection, and four showed associated cytomegalovirus (CMV) pneumonitis. Seven patients had two biopsies each of BOOP-LR, of which six were ass ociated with ongoing minimal or mild acute rejection, and one had reso lving mild acute rejection. Three patients had three biopsies each of BOOP-LR, all associated with ongoing minimal or mild acute rejection. Two patients had four biopsies each, showing BOOP-LR with ongoing mild or moderate acute rejection or CMV pneumonitis. Forty of the total 11 5 lung transplant patients (34.8%) have developed bronchiolitis oblite rans syndrome (BOS) or chronic airway rejection. Twelve of these patie nts are from the study group, of which five have a biopsy proven histo logical diagnosis of obliterative bronchiolitis (OB), and the remainin g seven patients have been diagnosed clinically by deteriorating lung function tests, The authors conclude that BOOP-LR in the lung transpla nt setting result from acute epithelial injury secondary to either all oqraft rejection or an ongoing infection and are not a component of, n or do they necessarily predispose to, chronic rejection. Copyright (C) 1996 by W.B. Saunders Company.