Lipoid pneumonia

Lipoid pneumonia can either result from aspiration of oily substances (exogenous lipoid pneumonia) or endogenous accumulation of lipid substances in the alveoli (endogenous lipoid pneumonia).

Most patients are asymptomatic and often discovered incidentally.

Lipid-laden macrophages are often seen histological samples following transthoracic needle biopsy. With exogenous forms, inhaled lipid content (e.g. from aspiration) is phagocytosed by macrophages which fill alveoli. A subsequent acute + / - chronic pneumonitis results.

Macroscopically the affected regions often have yellowish or golden hue, which is thought to be produced by the liberation of lipid material from alveolar pneumocytes secondary to the inflammatory reaction. 

Risk factors
  • aspiration risk
    • neuromuscular disorders
    • oesophageal abnormalities
    • cleft palate
Associations

The endogenous type can be seen in association with lung cancer 2.

Complications

A fibrotic component can develop in chronic cases.

Other possible complications include

  • superinfection by nontuberculous mycobacteria
  • respiratory insufficiency
  • cor pulmonale
  • hypercalcemia
Plain radiograph
  • can be variable 3
  • radiological spectrum with consolidation to irregular mass like lesion to a reticulonodular pattern
CT
  • characteristically show low attenuation within the consolidated areas of ~ -100HU reflecting a fat content (at times the attenuation value may be less i.e. around -30 HU)
  • consolidation may have a predilection for the dependent portions of the lungs 3
  • associated ossific foci may be present within the affected region
  • a crazy paving pattern may also be seen
MRI

Not part of routine evaluation. Signal characteristics may reflect fat / paraffin content. usually:

  • T1: high to intermediate signal 7
  • T2: low to intermediate signal 7

The mainstay of management in exogenous types is control and cessation of offending agent(s).

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Article Information

rID: 9967
System: Chest
Synonyms or Alternate Spellings:
  • Lipoid pneumonias
  • Lipid pneumonia
  • Lipid pneumonias
  • Lipoid pneumonia - general

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Cases and Figures

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    Case 3: acute exogenous lipoid pneumonia
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    Case 4: complicated by NTB infection
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