forms of pulmonary lymphoma 8 can affect an entire lobe.lung adenocarcinoma affecting an entire lobe.atelectasis - tends to be associated with more volume loss, and is more enhancing compared to pneumonia 10.note that both bland and purulent effusions may result in subsequent scarring/adhesions depending on the degree of fibroblastic organization 2įor radiographic appearances of consolidation, consider other forms of lobar consolidation such as:.empyema - purulent fibrinous inflammatory reaction due to infectious spread into the pleural space.
parapneumonic effusion - fibrinous inflammatory reaction to the adjacent pulmonary inflammation. Radiological follow-up of lobar pneumonia is often recommended - one study found ~5% of initially suspected community-acquired pneumonia were re-diagnosed with malignant or important benign pulmonary pathology on follow-up chest radiographs/CT (average follow-up at 11.5 weeks) 9. However, there is overlap, and also factors such as pulmonary hemorrhage and underlying malignancy likely affect the lung density. For example, one small study used a threshold of 85 HU to distinguish between atelectasis versus pneumonia on CT PE protocol with a sensitivity of 90% and specificity of 92% 10. On contrast-enhanced CT, pneumonia often enhances less than atelectatic lung, although there is no clear Hounsfield unit threshold to distinguish the two. There may be additional associated areas of ground-glass opacity in a lobar or segmental pattern, likely representing areas of partial involvement or simply atelectasis 1. CTĬlassically, lobar pneumonia appears as a focal dense opacification of the majority of an entire lobe with relative sparing of the large airways. The non-opacified bronchus within a consolidated lobe will result in the appearance of air bronchograms. Strictly speaking, consolidation is not associated with volume loss however, atelectasis can occur with small airway obstruction. The opacification can be sharply defined at the fissures, although more commonly there is segmental consolidation 3. Red and grey hepatisation refers to the gross morphological appearance of a lung with inflammatory exudate in the alveolar spaces.Ĭharacteristically, there is homogeneous opacification in a lobar pattern. resolution: final stage of processing the residual exudate. grey hepatisation: fibrinopurulent inflammatory alveolar exudate. red hepatisation: hemorrhagic inflammatory alveolar exudate. congestion: hyperemia, with alveolar edema and bacterial proliferation. The gross and histologic appearance of the infected lung can be broken down into four stages of inflammation 2: Other causative organisms that may cause a lobar pattern include 1: 
The most common cause of lobar pneumonia is Streptococcus pneumoniae. There is characteristic relative sparing of the bronchi, creating the appearance of air bronchograms. The distribution of consolidation is lobar because of the spread of infection across segmental boundaries - facilitated by the pores of Kohn and the canals of Lambert 3 - although limited by pleural boundaries. Consolidation in lobar pneumonia mainly affects the alveolar air spaces.
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