Discussion

Lipoid pneumonia is a rare, primarily chronic inflammatory reaction secondary to the presence of lipid substances in the lungs, with subsequent uptake by alveolar macrophages and accumulation in the interstitium. The endogenous form occurs when fat is deposited into the lung tissue in vivo, typically from proximal obstructive lesions, fat embolism, necrotic tissue, lipid storage disease, or hyperlipidemia. The exogenous form develops from inhaling or aspirating lipids, such as those seen in animal, vegetable, or mineral oil. Classically, exogenous lipoid pneumonia is associated with aspiration of mineral oil-based laxatives in the pediatric population or with occupational exposures. The incidence is also higher in older patients with underlying debility, achalasia, reflux, and other neuromuscular disorders of the pharynx and esophagus.

Most patients are asymptomatic; however, symptoms may include cough, dyspnea, fever, weight loss, chest pain, pleurisy, hemoptysis, chills, and night sweats. Findings on physical examination may be normal or nonspecific, such as tachypnea and adventitious breath sounds. Thus, a high clinical suspicion is required to make the diagnosis of exogenous lipoid pneumonia.