Bronchiolitis obliterans organizing pneumonia (BOOP) in a child with mild-to-moderate asthma: evidence of mast cell and eosinophil recruitment in lung specimens

Abstract Bronchiolitis obliterans with organizing pneumonia (BOOP) is rarely described in children and little is known about its pathogenesis. This paper reports on an 11-year-old patient suffering from mild-to-moderate asthma. He presented with a retrocardiac density at chest computed tomography scan that was slow to resolve and failed to respond to antibiotic therapy. Open lung biopsy revealed a histological picture with buds of granulation tissue in respiratory bronchioles and alveolar ducts, with organized extensions into the alveoli. The use of monoclonal antibodies on biopsy specimens demonstrated the presence of an inflammatory process affecting not only the thickened alveolar walls, but also the remaining lung parenchyma, the pulmonary arteries, and the bronchioles. The inflammatory infiltrate consisted mainly of mast cells and eosinophils. The clinical condition improved with steroid therapy. To the best of the authors' knowledge, this is the first report of BOOP in an asthmatic child with recruitment of mast cells and eosinophils documented by using monoclonal antibodies.