Round pneumonia

Last revised by Francis Deng on 25 Nov 2023

Round pneumonia is a type of pneumonia usually only seen in pediatric patients. They are well defined, rounded opacities that represent regions of infected consolidation.

The mean age of patients with round pneumonia is 5 years and 90% of patients who present with round pneumonia are younger than 12 years 5. Round pneumonia is uncommon after the age of 8 years because collateral airways tend to be well developed by this age 2,5.

Patients present with symptoms of chest infection including fever, sweats, and cough. A history of infective symptoms is helpful when excluding other imaging differentials.

The proposed theory as to why children develop round pneumonia and adults do not relates to the development of inter-alveolar communications and collateral airways. These are called pores of Kohn and canals of Lambert, and when they develop, they allow air-drift between the parenchymal subsegments. In adults, these allow lateral dissemination of infection throughout a lobe, leading to lobar pneumonia. In children, where these have not developed, the limited spread of infection results in round pneumonia 2-4

The infective agent in round pneumonia is bacterial. There is no specific bacterium that causes round pneumonia, but since Streptococcus pneumoniae is the most common cause of chest infection, it is little surprise that it is the leading cause of round pneumonia 4. Haemophilus influenza is also a causative organism 6.

Round pneumonias are round-ish and while they are well-circumscribed parenchymal opacities, they tend to have irregular margins. They most commonly occur in superior segments of lower lobes and in the majority of cases (98%), they are solitary 5.

Air bronchograms are often present though are only seen in 17% of cases when they occur in adults 2.

If round pneumonia is confidently diagnosed, it does not require further investigation. With antibiotic therapy and resolution of symptoms, it does not require follow-up.

If a follow-up radiograph is performed, 95% of cases will have resolved by 30 days. Only a minority of cases (5%) progress to lobar pneumonia 5.

In children consider:

In adults consider:

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