Round pneumonia

A 6-year-old girl presented with a 3-day history of fever, diffuse abdominal pain and lumbar pain, followed by cough and chest pain.

The initial AP chest radiograph (Fig. 1) showed a rounded/oval opacity in the right middle zone, adjacent to the cardiac silhouette. The limits of the cardiac silhouette were preserved, suggesting involvement of the right lower lobe.

The lateral view confirms this location, as the opacity is projected over the posterior aspect of the lungs, at the level of the vertebral bodies of T7 and T8 (possibly located in the superior segment of the right lower lobe).

If the opacity had been located in the right middle lobe (in its medial segment), there would be loss of this silhouette. The lateral projection, by showing the opacity in the posterior aspect of the lung fields, again excludes the location being in the middle lobe, whose two segments are more anterior.

The explanation about why children develop round pneumonia refers to the absent development of collateral pathways of air circulation (pores of Kohn and channels of Lambert). This way, spread of infection is limited, resulting in confluent areas of consolidation. If they were developed, that would allow dissemination of infection through a lobe, resulting in lobar pneumonia. [1]

The mean age of presentation is 5 years of age. As in our case, it is usually solitary (>90%), circumscribed (70%), located posteriorly (83%) and in the lower lobes (65%), especially the superior segment of the lower lobe. [1]

Although lateral radiographs are not routinely necessary in children, this case started with less specific symptoms, thus at first glance the hypothesis of pneumonia was not clearly demonstrated. Additionally, it is occasionally performed in gradeschoolers in Brazil. [3]

The major differential diagnosis includes lung and mediastinal tumours and tumour-like lesions. In the clinical context of an acute illness, an infectious cause is much more likely and must lead to antibiotic therapy. [2] No further evaluation for neoplasm is needed. With treatment and resolution of symptoms, most community-acquired pneumonias do not require follow up; however, round pneumonia is one of the exceptions in which a radiography should be considered several weeks later to ensure resolution of the opacity, as well as in those with collapse or persisting symptoms [3]. Misdiagnosis of other diseases as round pneumonia is infrequent.