Exogenous Lipoid Pneumonia
Taichi Kaneko, Ryota Otoshi
N Engl J Med 2025;392: e12
DOI: 10.1056/NEJMicm2407298
A 38-year-old woman was referred to the pulmonary clinic for evaluation of an opacity in the right lower lobe seen on chest radiography. She had no respiratory symptoms but did report a 6-year history of disordered eating in which she would consume large amounts of salad oil and then induce vomiting. On physical examination, fine crackles were heard in the lower lobes. High-resolution computed tomography of the chest showed ground-glass opacities with the density of fat tissue, predominantly in the right lower lobe (Panel A). Bronchoscopy was performed, during which yellow secretions were observed in the bronchial lumen (Panel B, asterisk); the secretions separated out in the bronchoalveolar-lavage (BAL) fluid (Panel C, arrow). Cytologic examination of the BAL fluid showed lipid-laden macrophages and extracellular droplets of oil (Panel D, Sudan III stain). Histopathological analysis of a lung-biopsy specimen showed numerous macrophages phagocytosing lipid droplets (Panel E, Sudan III stain). A diagnosis of exogenous lipoid pneumonia was made. Exogenous lipoid pneumonia is caused by aspiration of oil. It may manifest as an acute, inflammatory respiratory syndrome or as a more insidious condition. Cognitive behavioral therapy for the eating disorder was initiated. Six months after remission of the eating disorder, the findings on imaging had resolved.
