(aka Exogenous Lipoid Pneumonia)

Types of Oil

• Mineral Oils (most commonly aspirated oils) -> oil droplets are taken up by macrophages, macrohages disintegrate and release the oil droplets, which inhibit ciliary activity (therefore, oil is not expectorated and cycle continues) -> leads to development of fibrotic or granulomatous reaction
• Neutral Oils: vegetable oils -> do not elicit a local reaction and are removed by expectoration
  • Olive Oil
  • Castor Oil
• Animal Fats: rapidly hydrolyzed -> liberated fatty acids produce tissue necrosis and subsequent fibrosis
  • Milk
  • Butter

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Etiology of Exogenous Lipoid Pneumonia

• Nocturnal Aspiration of Mineral Oil: usually in older patients as a treatment for constipation
  • Mineral oil is a mix of inert long-chain saturated hydrocarbons (obtained from petroleum)
  • Mineral oil inhibits the cough reflex and ciliary motility, facilitating inhalation
• Aspiration of Petroleum Gels
  • Vicks Vapo-Rub: used for dry nasal passages
  • Petroleum Gel Used to Lubricate ET Tube: during intubation
• Aspiration of Other Oils
  • Oily nose drops
  • Olive oil
  • Milk
  • Cod liver oil
  • Paraffin oil
  • Poppy seed oil
  • Methenamine mandelate suspension (urinary antiseptic)

• Aspiration of Oil-Based Sprays

  • Motor oil sprays
  • Industrial oil sprays

• Cyclosporin A (CSA):

• Iodine/Radiographic Contrast:

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Physiology

• Aspiration of exogenous lipid (oily nosedrops/mineral oil/etc) into lungs
• Underlying GERD is an important contributing factor

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Clinical Presentations

• Asymptomatic
• Lung Nodule
  • Diagnosis
    • CXR/Chest CT: solitary lung nodule
• Alveolar or Interstitial Pneumonia (see [[Pneumonia]] and [[ILD-Etiology]])
  • Diagnosis
    • CXR/Chest CT
      • Alveolar infiltrates: especially in the lower lobes
      • ”CT Angiogram Sign”: branching pulmonary arteries seen within consolidated lung on Chest CT -> however, this sign is not specific for lipoid pneumonia
      • HRCT: “Crazy Paving” -> ground glass density in a mesh-work of reticular lines representing thickened intralobular septa (this pattern is typical for alveolar proteinosis, but has also been reported with lipoid pneumonia and other conditions)
    • FOB:
      • BAL: before fixation, stained with oil-red-O or Sudan red will show alveolar macrophages with vacuolated cytoplasm (this strongly suggest the diagnosis in the proper clinical setting)
      • TBB: characteristic circular empty spaces in tissue sections (due to loss of lipid during prep) with surrounding inflammation
    • OLB: vacuolated intra-alveolar macrophages
      • Foreign-body granulomas with giant cells
      • Chronic: granulomatous pneumonitis with fibroblastic proliferation, fibrosis, masses of foamy macrophages, foreign-body giant cells
• Acute Lung Injury-ARDS (see [[Acute Lung Injury-ARDS]])
  • Epidemiology: may occur

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Treatment

• Withdraw Agent
  • 46% of cases improve
  • 25% stabilize
  • 21% continue to deteriorate (due to fibrosis and respiratory failure)
• Corticosteroids: effective in acute and subacute cases
  • May be effective in a few chronic cases
• Whole Lung Lavage: has been used in some cases

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References

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