Round Pneumonia

  • 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

Cases of Round Pneumonia

CXR of round pneumonia
Initial CXR PA (above left) shows a large round opacity located medially in the right hemithorax which is located posteriorly on the lateral (above right) over the spine (spine sign). CXR PA obtained 5 days later (below) shows interval resolution of the mass.