Round pneumonia: imaging findings in a large series of children

Background Although round pneumonia is a well-known clinical entity, there have been no large case reviews, with most knowledge based on case reports and small series from the 1960s and 1970s. Objective To review the imaging findings of a large series of children with round pneumonia. Materials and methods A retrospective review of radiographic and CT findings in all children reported to have round pneumonia at a large children’s hospital from 2000 to 2006 was performed. Children with underlying medical conditions were excluded. Epidemiologic characteristics, radiographic and CT findings, and follow-up imaging were reviewed. Results The review identified 109 children (mean age 5 years, range 4 months to 19 years). Round pneumonias tended to be solitary 98% (107/109), have well-defined borders 70% (77/109), and be posteriorly located 83% (91/109), with the following lobar distribution: left lower lobe (36), right lower lobe (33), right upper lobe (28), left upper lobe (7), right middle lobe (4), and lingula (2). Round pneumonia tended to resolve on follow-up imaging (95%, 41/43) as compared to progression to lobar pneumonia (4.6%, 2/43). Three patients (2.6%, 3/112) originally suspected to have round pneumonia were later shown to have other diagnoses: cavitary necrosis in pneumonia (two) or pleural pseudocyst (one). Conclusion Round pneumonia occurs in young children (mean age 5 years), tends to be a solitary lesion, and is most commonly posteriorly located. Misdiagnosis of other pathology as round pneumonia is uncommon.