Idiopathic Bronchiolitis Obliterans Organizing Pneumonia: Case Review

Bronchiolitis obliteans organizing pneumonia (BOOP) is characterized clinically by a subacute or chronic respiratory illness. The purpose of this study was to describe clinical and radiologic features of Idiopathic (cryptogenic) bronchiolitis obliterans organizing pneumonia. We retrospectively reviewed 11 patients with biopsy proven BOOP at Masih Daneshvari Hospital, for whom well documented clinical and radiographic data were available. The final diagnosis of BOOP was validated if the followings were present:1) Negative sputum or bronchoalveolar lavage (BAL) analysis for Mycobacterium tuberculosis2) Open lung biopsy (OLB) or trans-bronchial lung biopsy (TBLB) findings characteristic of BOOP 3) Negative findings for systemic disorders or associated primary pulmonary lesions such as cancer 4) Prompt response to steroid therapy. The mean age of patients with BOOP in this case series was 46.3±24.6 yrs.(range 32-70); the male/female ratio was 7/4. The clinical pattern in BOOP presentation was more similar to classic sub-acute infectious process: dyspnea in 9 patients (81.8%), fever in 5 (45.4%), and cough in 6 (54.5%). The symptoms were usually mild. Physical examination showed sparse crackles in 5 patients (45.4%) and wheezing in 7 (63.6%). The most frequent radiologic patterns were ground glass appearances (63.6%) and diffuse infiltration associated with reticular pattern (27.2%). In 6 patients chest images showed bilateral distribution. The clinical and radiological manifestation of BOOP in our patients did not differ from other reports. BOOP cases may present a distinct entity like pneumonia. Physicians in charge of these patients were all surprised of BOOP diagnosis by tissue examination. Trans- bronchial lung biopsy specimens along with strongly suggestive clinical and radiologic findings in many cases were adequate for making the diagnosis. We suggest that the diagnosis of BOOP must be considered in any immunocompetent patient with pneumonia with poor or no response to antibiotic therapy.