Clinical and Radiologic Distinctions Between Secondary Bronchiolitis Obliterans Organizing Pneumonia and Cryptogenic Organizing Pneumonia

BACKGROUND: Bronchiolitis obliterans organizing pneumonia (BOOP) is a distinct pattern of reaction of the lung to injury. It may be idiopathic or secondary to a variety of injuries. The term cryptogenic organizing pneumonia (COP) is used for patients with idiopathic BOOP. In this study we describe clinical and radiologic features of patients with BOOP.

METHODS: The medical records of 33 patients with diagnosis of BOOP on surgical lung biopsy over a 10-year time period were reviewed retrospectively. We obtained data on clinical and radiologic manifestations, etiology, and outcome of these patients.

RESULTS: Dyspnea was the most common symptom, followed by dry cough and fever. Crackles was the most common physical finding. Mean age at diagnosis of BOOP was 59 years, and 42% were females. The main radiologic manifestation was bilateral patchy consolidation. Most patients had favorable prognosis; however, 17% did not respond to treatment. Female sex was more common in COP than in secondary BOOP (P = .004). Patients with COP had longer symptom duration before the diagnosis than secondary BOOP (P = .01). Patients with secondary BOOP reported fever more frequently, compared to COP (P = .005). Pleural effusion was present in 60% of patients with secondary BOOP, whereas none of the patients with COP had effusion (P = .004).

CONCLUSIONS: COP and secondary BOOP have diverse clinical and radiologic manifestations. Patients with secondary BOOP are more symptomatic. Both COP and secondary BOOP patients have good prognosis, and most respond to treatment with corticosteroids or by discontinuing the injurious drug.