C43-08 Plastic Bronchitis in Adults With and Without Evidence of Thoracic Lymphatic Abnormalities: A Case Series

Abstract Plastic bronchitis (PB) is a condition characterized by expectoration of thick bronchial casts, which can cause obstruction and respiratory failure. While pediatric PB is more recognized in the context of congenital heart disease, adult PB remains exceedingly rare, underdiagnosed, and poorly understood. We present a series of five adult patients with PB to highlight the diagnostic complexity, the variable lymphatic abnormalities noted on imaging, and response to therapies. Case 1 A 68-year-old woman with a remote history of breast cancer presented with progressive dyspnea, cough, and hypoxemia requiring intubation and mechanical ventilation. Bronchoscopy confirmed PB. Despite multiple therapeutic bronchoscopies, casts rapidly re-accumulated. Lymphangiography showed no active extravasation; empiric thoracic duct embolization (TDE) was performed. She was extubated and symptoms resolved. Case 2 A 74-year-old woman with a history of COPD developed recurrent left mainstem obstruction requiring intubation and mechanical ventilation after thoracic endovascular aortic repair. Serial bronchoscopies revealed thick airway casts, with bronchoalveolar lavage cultures growing Enterococcus faecium. Lymphangiogram demonstrated active extravasation into the left lung (figure 1). TDE improved her respiratory failure; however, she later died from multisystem organ failure. Case 3 A 40-year-old man with prior lymphoma and chest radiation presented with chronic cough and bronchial cast expectoration. Lymphangiography revealed abnormal thoracic duct branches with flow into both lungs. TDE was performed; follow-up was limited. Case 4 A 33-year-old man with a history of thoracic stab wounds presented with cough and copious chylous sputum. Lymphangiography revealed retrograde lymphatic flow. He underwent thoracic duct ligation with near-complete resolution of symptoms. Case 5 A 42-year-old woman with eczema and allergies presented with recurrent cast expectoration and abnormal left lung lymphatic vessels on lymphangiography. TDE resulted in complete symptom resolution at six-week follow-up. Adult PB encompasses a spectrum of lymphatic and inflammatory etiologies. Only one of our five cases had a lymphangiogram without active extravasation, suggesting an inflammatory or infectious process. These findings are consistent with prior case reports suggesting chronic inflammation or infection may trigger lymphatic remodeling or mucin hypersecretion, leading to cast formation. Thoracic duct ligation can be effective even in the absence of abnormal lymphatic leakage on lymphangiography. Bronchoscopic airway clearance is essential, regardless of the underlying cause. Many patients experience delayed or missed diagnosis, as recognition of adult PB requires a high index of suspicion when evaluating respiratory failure with casts. Further research is needed to clarify risk factors, optimize diagnostic imaging, and standardize interventional approaches. This abstract is funded by: none