B80-5-52 Imposter Among Us: Bronchial Neuroendocrine Tumor Mimicking Non-Resolving Pneumonia

Abstract Introduction Persistent lobar collapse in healthy individuals, initially presumed pneumonia, mandates investigation for underlying issues like endobronchial lesions. Bronchial neuroendocrine tumors (NETs), though rare, frequently cause airway obstruction mimicking pneumonia. This case highlights diagnostic challenges and successful intervention. Case Presentation A 23-year-old non-smoking male initially presented with back pain; imaging showed pneumonia. Despite antibiotic treatment and symptomatic improvement, a follow-up chest X-ray revealed persistent left lower lobe whiteout. Subsequent CT imaging confirmed complete left lower lobe collapse due to an obstructing endobronchial mass, with suspected necrosis and a prominent subcarinal lymph node. Initial labs showed elevated ESR (29 mm/hr) and CRP (6.7 mg/L), alongside an elevated Chromogranin A (224.1 ng/ml). Urinary 5-HIAA was negative. Bronchoscopy with snare debulking confirmed a Grade 1 Neuroendocrine Tumor (Typical Carcinoid) with neuroendocrine markers positive, a Ki-67 of approximately 3%, and notably, focal necrosis. Post-debulking, his chest X-ray improved. A PET scan showed localized disease. The patient underwent a left lower lobe lobectomy of a large (baseball-sized) tumor with extensive lymph node dissection. Post-operative pathology confirmed Grade 1 NET with clear margins. The patient is currently well and under surveillance. Discussion This case illustrates the deceptive presentation of a bronchial NET mimicking non-resolving pneumonia in a young adult. Initial symptomatic relief can mask a critical structural lesion, emphasizing the need for vigilant follow-up imaging. The pathological diagnosis of “typical carcinoid” was complicated by focal necrosis, a feature more commonly associated with atypical carcinoids. This nuance underscores the complexity of NET grading and likely influenced the decision for lobectomy and extensive lymph node dissection, a strategy often reserved for higher-grade or atypical tumors due to their increased incidence of lymph node involvement. The negative 5-HIAA highlights the rarity of overt carcinoid syndrome in bronchial NETs, limiting its diagnostic utility in such cases. Conclusion This case demonstrates that prompt bronchoscopy and definitive tissue biopsy, combined with expert assessment of tissue morphology, are crucial for accurate diagnosis and curative treatment of bronchial NETs, even in nuanced pathological contexts and atypical clinical presentations. This abstract is funded by: none