Unmasking Carcinoid Syndrome in a Chronic Obstructive Pulmonary Disease (COPD) Patient: A Rare Presentation with Wheezing and Angioedema.

Carcinoid syndrome is a rare condition resulting from neuroendocrine tumors (NETs) that secrete vasoactive substances like serotonin. This report describes the case of a 61-year-old man with a history of chronic obstructive pulmonary disease (COPD) and hypertension who presented with new-onset angioedema, loss of consciousness, and a fall. He had been treated for COPD exacerbations during ER visits without improvement and was unaware of a prior mesenteric carcinoid tumor diagnosis from 2012. The next emergency evaluation revealed significant airway and facial edema necessitating intubation. Imaging and biopsy identified a well-differentiated grade 1 NET with extensive liver metastases. Laboratory tests showed elevated levels of serum serotonin, chromogranin A, and 24-hour urine 5-hydroxyindoleacetic acid (5-HIAA). Post-discharge, a PET scan confirmed metastatic lesions primarily in the liver and small bowel, with an unresectable mesenteric mass. The patient was treated with lanreotide and became symptom-free. This case underscores the need to consider carcinoid syndrome in patients with COPD presenting with unexplained respiratory symptoms, as timely diagnosis and treatment can significantly enhance patient outcomes.