Bronchiolitis obliterans organising pneumonia simulating bronchial carcinoma.

Idiopathic bronchiolitis obliterans organising pneumonia (BOOP) is an uncommon but well-recognised condition that usually presents radiologically as bilateral multifocal patchy areas of consolidation on the chest radiograph and on computed tomography (CT). Five cases are described in which the presenting feature was that of a solitary pulmonary nodule. Four of these nodules showed evidence of cavitation and three patients presented with haemoptysis. In all cases the appearances closely resembled bronchial carcinoma.