[Clinicopathologic study of various lung diseases with bronchiolitis obliterans organizing pneumonia (BOOP) pattern...

The histologic findings of BOOP are nonspecific, and the diagnosis of idiopathic BOOP is one of exclusion. We studied the clinicopathologic features of various lung diseases with histopathological appearance of bronchiolitis obliterans organizing pneumonia (BOOP) pattern in open lung biopsy specimens. The 17 patients with BOOP pattern studied included idiopathic BOOP (n = 7), unclassified interstitial pneumonia (n = 1), collagen vascular disease (n = 3, RA 1, PM/DM 2), hypersensitivity pneumonitis (HP, n = 2), eosinophilic pneumonia (EP, n = 1), multiple lung abscesses (n = 1), limited form of Wegener's granulomatosis (n = 1), and pneumocystis carinii pneumonia associated with adult T cell leukemia (n = 1). There were no differences in clinical symptoms, laboratory data, respiratory function, and cytological findings in bronchoalveolar lavage fluid (BALF) between cases of idiopathic BOOP and other lung diseases. The duration of clinical symptoms was less than one year in 16 patients (one case had no symptoms). Chest X-rays showed bilateral patchy, nodular, or reticular shadows in all cases. Multiple patchy migratory shadows were only observed in cases of idiopathic BOOP or EP. Organizing pneumonia was recognized in the transbronchial lung biopsy specimens of all patients with idiopathic BOOP, HP or EP. Regarding prognosis, relapses occurred in idiopathic BOOP (n = 5), polymyositis, EP, limited form of Wegener's granulomatosis, and Pneumocystis carinii pneumonia. Four patients with idiopathic BOOP relapsed when steroid therapy was decreased or stopped. These findings indicate that idiopathic BOOP should be differentiated from other lung diseases, and these patients should be followed for a long period of time.