Case Presentation: A 19-year-old female with past medical history of asthma, GERD, and anxiety presented with chief complaint of dyspnea, fever, pleuritic chest pain, and vomiting. She was diagnosed with community acquired pneumonia based on multifocal opacities on CT and started on ceftriaxone and azithromycin with initial improvement of symptoms and leukocytosis. On hospital day 2, she had clinical deterioration with hypoxemic respiratory failure and fever. Repeat CT chest showed no changes. Respiratory viral panel and 2 sets of blood cultures were negative. Antibiotics were escalated to piperacillin/tazobactam. Further history revealed a 3-months of progressive malaise, night sweats, and loose stools with no recent travel or IV drug use. No exposure to livestock or TB endemic areas were reported. Testing for GI PCR panel, CMV, Ehrlichia, Rickettsia, Brucella, Borrelia, Histoplasma, Legionella, HIV, HCV, and Syphilis were all negative. On further history taking it was discovered that the patient vaporizes several different nicotine and marijuana products daily. She would often have a burning sensation down her throat and into her chest while using these products. Cultures of bronchoalveolar lavage showed no growth, but cytology revealed lipid laden macrophages, consistent with exogenous lipoid pneumonia. All antibiotics were stopped, and she improved with supportive care alone. She was discharged few days later with plans for CT chest and PFTs 4-8 weeks later.
Discussion: Lipoid pneumonia is a rare entity with increasing prevalence given the rise in vape use among the youth. It is classified into two major groups, exogenous and endogenous / idiopathic . It is a common pediatric diagnosis in South America where cultural practices include using fat obtained from the rump of hens for medicinal purposes. Infants inadvertently aspirate it into the lung causing symptoms. Case reports link inhalation or ingestion of petroleum jelly, mineral oils, nasal drops and even IV injection of olive oil to exogenous lipoid pneumonia [2,3].On histopathology, lipoid pneumonia is characterized by lipid-laden macrophages . Treatment options are sparse and not well studied. A trial in children with mild-to-moderate symptoms showed no clinical or radiological benefits with use of systemic corticosteroids . Steroids are still utilized, however, on a case-by-case basis in adult patients. There are cases of successful treatment of lipoid pneumonia with immunoglobulins  and whole lung lavage . Supportive care remains the mainstay of treatment. Due to its nonspecific presentation with symptoms more characteristic of an infectious process the diagnosis is often missed or delayed.
Conclusions: Hospitalists should be familiar with lipoid pneumonia due to its nearly identical presentation to bacterial pneumonia and increasing prevalence with the rise of vaping in young adults.