Abstract Introduction Lipoid pneumonia is an uncommon, often under-diagnosed inflammatory lung condition, classified as either exogenous from aspiration of oils, inhaled oils, vapes or endogenous, from lipid accumulation in the alveoli secondary to bronchial obstruction or infection. Histologically, macrophages ingest lipids, forming lipid-laden masses (paraffinomas) causing post-segmental bronchial obstruction. Symptoms can mimic community-acquired pneumonia or lung cancer, making diagnosis challenging. Symptoms include cough, dyspnea, fever, and weight loss. Squamous cell carcinoma (SCC) is a central lung malignancy, subtype of non-small cell lung cancer, common in smokers. Symptoms overlap with lipoid pneumonia: persistent cough, dyspnea, weight loss, and recurrent infections. When symptoms do not resolve with antibiotic use, further workup for malignancy is warranted. Case Presentation 74-year-old female with COPD, insulin-dependent type 2 diabetes, chronic hypoxic respiratory failure on 3L nasal cannula oxygen, asthma, hypertension, and a 25-pack/year active smoker, presented with a one week of worsening shortness of breath, hyperglycemia, nausea, vomiting, diarrhea, dry cough, pruritic rash on hands, and unintentional weight loss. Diagnosed with diabetic ketoacidosis (DKA) and lower lobe lipoid pneumonia. Initiated on broad-spectrum antibiotics, insulin drip and intravenous fluids. Vancomycin added due to history of MRSA. On day 2, she developed an anaphylactoid reaction, likely from vancomycin, with a worsening rash and hypotension requiring ICU transfer, epinephrine drip, and supportive care. Vancomycin was switched to linezolid. Bronchoscopy with bronchial alveolar lavage was performed. Cytology revealed squamous cell carcinoma. Patient opted for no further oncologic treatment and chose discharge home with family for comfort care.Treatment:For lipoid pneumonia, Removal of inciting agents, supportive care, and steroids in select cases. For SCC, surgical resection, neoadjuvant chemoradiation, targeted therapies, or palliative care based on staging and patient goals. Discussion This case highlights how lipoid pneumonia may mask underlying malignancies, particularly in high-risk patients, such as long-term smokers. Although this patient had no known history of mineral oil use, vaping, or salon work. Her imaging suggested lipoid pneumonia. However, persistent symptoms, including the notable weight loss and chronic cough along with non-resolving pneumonia, prompted further investigation. This case emphasizes the importance of pursuing bronchoscopy and cytologic evaluation in atypical or unresolving pneumonia cases. Conclusion Lipoid pneumonia, while rare, should prompt further evaluation for refractive pneumonia especially in patients with underlying risk factors for malignancy such as smoking and weight loss. Bronchoscopy with BAL and cytology is essential for distinguishing benign inflammatory processes from malignancy. Clinicians should maintain a high index of suspicion in such presentations. This abstract is funded by: None
Harrell-Mitchell et al. (2026) studied this question.