Findings: AP and lateral chest x-rays reveal diffuse, bilateral reticulonodular infiltrates without pleural effusions. The heart size is normal. There is no significant deviation of the trachea.
Diagnosis: Bronchiolitis obliterans organizing pneumonia.
Discussion: Patients with BOOP are usually between the ages of 40-70, and present with a history of dry cough and SOB of two weeks to two months in duration. These symptoms persist despite antibiotic therapy. On auscultation of the lungs late inspiratory crackles are heard. The patient often has an elevated ESR, and PFTs demonstrate a decreased diffusion capacity and a restrictive pattern (diminished FC and TLC with a normal FEV/FV ratio).
The etiology of BOOP may be idiopathic or secondary to viral illness (RSV, adenovirus), collagen vascular disease, (RA, SLE), caustic inhalation (sulfur dioxide, chlorine), heart-lung transplant and chronic aspiration. The diagnosis is made histologically, via open lung biopsy since transbronchial biopsy frequently yields inadequate tissue specimens. Fibrous plugs and granulation tissue are present within terminal bronchioles as well as alveolar ducts and alveoli. In addition, perivascular mononuclear cell infiltrates are also seen. The interstitium is commonly involved, distinguishing BOOP from pulmonary fibrosis.
The most common chest x-ray finding is bilateral, patchy subpleural air-space opacities (69%), which can mimic lung masses. Pleural effusions and cavitations are rare. Similar radiographic appearances are typical for eosinophilic pneumonia, PE, septic emboli, bronchoalveolar carcinoma, metastatic disease and sarcoidosis.
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