Exogenous lipoid pneumonia from chronic mineral oil aspiration complicated by cavitary Mycobacterium abscessus infection

Lipoid pneumonia is a rare inflammatory lung disease that results from the accumulation of lipids within the alveoli. It is classified as either exogenous or endogenous based on the source of the lipid material. Endogenous lipoid pneumonia commonly occurs in inflammatory lung diseases resulting in damage to cell membranes, allowing lipids to leak out of cells and attract macrophages that subsequently alter lipid metabolism. Exogenous lipoid pneumonia is caused by aspiration or inhalation of lipid-containing substances such as mineral oil. Sometimes, exogenous lipoid pneumonia can predispose patients to atypical pulmonary infections, such as nontuberculous mycobacteria. A 40-year-old woman with a medical history significant for gastroesophageal reflux disease presented to our hospital with progressive dyspnea and cough for 3 months. She was found to have multifocal bilateral ground-glass and consolidative opacities on a computed tomography scan of the chest. She was treated multiple times for pneumonia with no significant improvement in her symptoms. Due to persistent symptoms, bronchoalveolar lavage was performed, showing cloudy fluid with yellowish material floating. Cytology was performed and showed lipid-laden macrophages on Oil Red O staining, suggesting a diagnosis of lipoid pneumonia. Upon further history, the patient reported chronic mineral oil intake for constipation. Mineral oil was stopped, and she was discharged in stable condition. A few months later, she presented with worsening symptoms, necessitating another bronchoscopy, with bronchoalveolar lavage cultures growing Mycobacterium abscessus . This case highlights the importance of recognizing the imaging features of exogenous lipoid pneumonia complicated by a superimposed nontuberculous mycobacteria infection.