B47-14 The Cough That Wouldn’t Go Away- Lymphangitic Carcinomatosis as the Initial Manifestation of Colonic Adenocarcinoma

Abstract Introduction Lymphangitic carcinomatosis is a rare cause of subacute progressive cough. This case explores typical and atypical features of lymphangitic carcinomatosis. Case A 38-year-old man with recent travel to Bermuda presented to urgent care with one week of dry, episodic cough and reduced exercise tolerance. He also endorsed a month of fatigue, headaches, and a 10-pound “intentional” weight loss. He denied any recent smoking or vaping. His initial physical exam noted normal vitals and clear lungs. Viral tests were negative. One week later, he returned to urgent care with worsening cough despite azithromycin. Repeat exam remained stable but CXR showed diffuse interstitial infiltrates and a perihilar opacity, concerning for pneumonia. He received a five-day course of levofloxacin plus azithromycin. Two weeks later, he re-presented to a community hospital with worsening exertional dyspnea. Labs showed mild leukocytosis. Viral panel, HIV testing, EKG, and TTE were unremarkable. He was started on broad-spectrum antibiotics. He rapidly decompensated, requiring intubation, mechanical ventilation, proning, and high-dose steroids for acute respiratory distress syndrome. Bronchoscopy with bronchoalveolar lavage and autoimmune work-up was unrevealing except for a positive antinuclear antibody. After six days in the ICU, he self-extubated and was discharged with steroids and home oxygen. The patient presented to an outpatient appointment in respiratory distress and was transferred to a university hospital. Chest x-ray showed pleural effusion and thoracentesis revealed malignant cells. A CT chest showed extensive septal thickening and a CT abdomen was concerning for a focal GI mass. Colonoscopy confirmed invasive sigmoid colon adenocarcinoma with lymphangitic carcinomatosis. He was hospitalized for five months with severe hypoxic respiratory failure requiring mechanical ventilation, tracheostomy, bilateral indwelling pleural catheters, and multiple chemotherapy regimens. His course was complicated by Pseudomonas pneumonia, malignant pleural effusions, pericardial effusion, C. difficile infection, and deep vein thrombosis. He was discharged to a rehabilitation center but re-presented three weeks later with worsening hypoxia. Within 24 hours of readmission, the patient died from cardiac arrest. Discussion This case highlights a rare cause of a common chief concern: cough. Early clues, such as unexplained weight loss and worsening fatigue despite antibiotics, warrant broader diagnostic consideration of autoimmune and malignant causes for patients with cough and dyspnea. Definitive diagnosis of lymphangitic carcinomatosis requires tissue sampling, which can be challenging in these patients, who are often critically ill and at higher risk during invasive procedures. This case underscores the importance of balancing aggressive interventions with timely palliative transitions. This abstract is funded by: None