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Lipoid pneumonia is a form of pneumonia associated with oily or lipid components within the pneumonitis component.
This can either result from:
aspiration of oily substances (exogenous lipoid pneumonia) or
endogenous accumulation of lipid substances in the alveoli (endogenous lipoid pneumonia)
Patients with a risk of aspiration have a greater risk of lipoid pneumonia, including those with:
The endogenous type can be seen in association with lung cancer 2.
Case reports are emerging in patients who use e-cigarettes (vaping) 12.
Most patients are asymptomatic and often discovered incidentally.
Macroscopically the affected regions often have a yellowish or golden hue, which is thought to be produced by the liberation of lipid material from alveolar pneumocytes secondary to the inflammatory reaction.
Lipid-laden macrophages are often seen in 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 pneumonitis results which may progress to chronic pneumonitis.
X-ray features are variable 3, and lipoid pneumonia may appear as consolidation, an irregular mass-like lesion, or a reticulonodular pattern.
characteristically shows low attenuation within the consolidated areas of around -100 HU reflecting fat content
at times the attenuation value may be greater, i.e. around -30 HU and higher than that of subcutaneous fat 10
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
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
Treatment and prognosis
Serial radiographs showing stability may be enough in asymptomatic patients with no background history. A biopsy can be performed in some of the cases to ensure the benign nature of the lesion, especially if changes are lipid-poor and imaging features persistent.
The mainstay of management in exogenous types is control and cessation of offending agent.
A fibrotic component can develop in chronic cases.
Other possible complications include:
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