Round pneumonia in a 50-year-old man.

Round pneumonia is a term referring to round or oval densities on chest x-ray. Round pneumonias have rarely been reported. First recognized in children, round pneumonias were due to Streptococcus pneumoniae or Haemophilus influenzae. Round pneumonias are probably frequently undiagnosed in the adult population, The appearance of such a pneumonia on chest x-ray may be round or oval, the borders may be smooth or lobulated. Round pneumonias may be accompanied by air bronchograms, and are usually located in the lower lobes of the lung. Most round pneumonias are small and solitary, but others are multiple and may be larger. Cavitation is not a usual feature of round pneumonias. Infiltrates may contain calcifications or be spiculated. There are many potential causes of round pneumonia, some of which are infectious and others are mimics of pneumonia. In adults the usual diagnostic challenge of a round pneumonia is to differentiate bacterial pneumonia from bronchogenic carcinoma.1,2