- Etiology: Streptococcus pneumoniae in 90%
- Imaging: due to absence / poor development of collateral airways due to immature lung anatomy, inflammation spreads centrifugally giving round appearance, in superior segments of lower lobes, solitary round opacity that is a mean of 3-4 cm in size
- (Collateral airways allow ventilation of alveoli through the channels bypassing the normal airway but are poorly developed in infants)
- (Channels of Lambert, pores of Khan for intralobular collateral circulation, Pathway of Martin for interlobular circulation)
- DDX: pulmonary mass so must get CXR 1 month post treatment to document resolution of mass
- Clinical: < 8 years old, peaks at 3-5 years old
Radiology Cases of Round Pneumonia
