Acute fibrinous and organizing pneumonia: initial presentation as a solitary nodule.

A 55-year-old man complained of cough and dyspnea. His chest radiograph and CT scan revealed a solitary nodule with a diameter of 2 cm, which showed an air bronchogram and had a hazy contour. After 3 weeks, the radiologic findings changed to diffuse infiltration with small centrilobular nodules, alveolar consolidation, and bronchial wall thickening. The alveoli contained numerous fibrin balls and organizing tissue, which are typical pathologic features of acute fibrinous and organizing pneumonia (AFOP), on histologic examination. We report the initial radiologic features of AFOP and suggest that there are some radiologic similarities between this condition and cryptogenic organizing pneumonia.