August 2012 imaging case of the month

No abstract available. Article truncated at 150 words. Clinical History: A 48-year-old non-smoking man presented with a history of slowly progressive shortness of breath and recent onset of a headache. Frontal chest radiography (Figure 1) was performed.Figure 1: Frontal chest radiography shows normal cardiomediastinal contours with bilateral peri- and infrahilar predominant ground-glass opacity with a background of linear and reticular abnormalities.Which of the differential diagnostic considerations listed below is the most likely consideration for the chest radiographic abnormality?1.Pneumococcal pneumonia 2.Lung carcinoma3.Idiopathic pulmonary fibrosis4.Pulmonary alveolar proteinosis5.Miliary tuberculosisCorrect!Answer: 4. Pulmonary alveolar proteinosisThe frontal chest radiograph shows bilateral increased lung attenuation consisting of ground-glass opacity and a background of linear and reticular abnormalities. Pneumococcal pneumonia is a possibility, but this infection most commonly presents either with an air-space pneumonia pattern [homogeneous lung opacity with air bronchograms extending towards the pleural surface] or with a bronchopneumonia pattern [patchy