When exogenous lipoid pneumonia mocks lung cancer

Exogenous lipoid pneumonia (ELP) is an uncommon disease resulting from the intra-alveolar accumulation of lipids of mineral, vegetal, or animal origin that induce an inflammatory reaction in the lungs. Radiologically (on chest computed tomography [CT] and 18F-fluorodeoxyglucose [FDG]-positron emission tomography [PET]), ELP may mimic different lung diseases, including lung cancer. Diagnosis requires the presence of lipid-laden macrophages in respiratory samples obtained by sputum, bronchoalveolar lavage fluid, fine needle aspiration cytology, or biopsy from lung lesions. Treatment of this illness is poorly defined, and the main intervention is avoiding the causing agent. An 80-year-old patient presented with exertional dyspnea and a dry cough for 4 months. Her chest computed tomography scan showed a ground glass nodule (GGN) with a small solid portion, which presented evidence of growth at the 3-month follow-up CT scan with spotty FDG-PET positivity. To rule out lung cancer, the case was discussed in our hospital multidisciplinary team meeting, and a CT-guided percutaneous transthoracic core needle biopsy was performed. The specimen from the lung lesion showed lipid-laden macrophages, and the patient reported three times a day consumption of a preparation based on Vaseline oil (33.3%), olive oil (33.3%), and almond oil (33.3%) used as a laxative. Therefore, a diagnosis of lipoid pneumonia was made. The patient was then addressed to an otolaryngologist and signs consistent with laryngopharyngeal reflux were found at the endoscopic examination. Lipoid pneumonia is still a challenging disease to diagnose, and lung cancer is one of the main differential diagnoses of ELP.