# Lipid pneumonia

Lipid pneumonia, also known as lipoid pneumonia, is a specific form of lung inflammation (pneumonia) that develops when lipids enter the bronchial tree. The disorder is sometimes called cholesterol pneumonia in cases where that lipid is a factor.

## Signs and symptoms

The pneumonia presents as a foreign body reaction causing cough, dyspnea, and often fever. Hemoptysis has also been reported.

## Causes

Sources of such lipids could be either exogenous or endogenous.

### Exogenous

Exogenous lipid pneumonia refers to lipoid pneumonia caused by something from outside of the body. For example, inhaled nose drops with an oil base, application of oil-based ointments such as Vaseline in the nasal passages, or accidental inhalation of cosmetic oil. Amiodarone is an anti-arrhythmic known to cause this condition. Oil pulling has also been shown to be a cause. Fire breather's pneumonia from the inhalation of hydrocarbon fuel is a specific variant. At risk populations include the elderly, developmentally delayed or persons with gastroesophageal reflux. Switching to water-soluble alternatives may be helpful in some situations.

#### Tuberculosis

Secondary tuberculosis in humans often begins as a lipid pneumonia. This may be due to high content of mycolic acid, cord factor, and Wax-D in the cell wall of M. tuberculosis, that has long been speculated to be a virulence factor of the mycobacteria.

### Endogenous

Endogenous lipid pneumonia can occur in the setting of airway obstruction. In this variant, lipid-laden macrophages and giant cells accumulate in the isolated bronchial airspace distal to the obstruction.

## Appearance

The gross appearance of a lipid pneumonia is that in which there is an ill-defined, pale yellow area on the lung. This yellow appearance explains the colloquial term "golden" pneumonia.
At the microscopic scale, foamy macrophages and giant cells are seen in the airways, and the inflammatory response is visible in the parenchyma.
On CT, lipoid pneumonia appears as a "crazy paving" pattern, characterized by ground glass opacities with interspersed interlobular septal thickening.

## Diagnosis

The evaluation of lipid pneumonia may include the following:
* Chest X-ray
* CT scan of the chest
* Arterial blood gas (pH)
* Bronchoscopy (histological sample)

## Management

There are no specific guidelines for the treatment of the disease. Limited evidence suggest that the corticosteroids and possibly intravenous immunoglobulins may improve condition but in the case of exogenous type the stopping of the offending agent is the step that should be taken first.

## Prognosis

Endogenous lipoid pneumonia and non-specific interstitial pneumonitis has been seen prior to the development of pulmonary alveolar proteinosis in a child.

## Epidemiology

Lipid pneumonia has been known to occur in underwater divers after breathing poorly filtered air supplied by a surface compressor lubricated by mineral oil.

## History

Laughlen first described lipid pneumonia in 1925 with infants that inhaled oil droplets. It is a condition that has been seen as an occupational risk for commercial diving operations but documented cases are rare.