Expectorated bronchial casts revealing lymphatic plastic bronchitis due to thoracic duct agenesis: case report.

backgroundPlastic bronchitis is a rare disorder most often linked to aberrant lymphatic drainage or congenital and acquired cardiac anomalies. In patients with lymphatic flow abnormalities, leakage or anomalous lymphatic-bronchial communications can allow lymphatic fluid to enter the airways, where it solidifies into gelatinous or rubbery bronchial casts that may obstruct airflow and are typically expectorated. CASE PRESENTATION: A 49-year-old man presented with chronic, recurrent expectoration of pale bronchial casts accompanied by episodic dyspnea and intermittent fever. A chest CT demonstrated right-lower-lobe ground-glass opacities, interstitial changes with a lymphatic distribution pattern, and mediastinal lymphadenopathy. Bronchoscopy was unremarkable, and sputum microbiology was negative. Pulmonary function testing showed a mild obstruction. Cytologic evaluation of an expelled cast revealed mucus with fibrin, erythrocytes, macrophages, lymphocytes, and neutrophils. MR lymphangiography identified a congenital absence of the thoracic duct. Abdominal lymph drained through two markedly dilated lymphatic vessels converging in the retromediastinum and supplying predominantly right-sided pulmonary lymphatics, with a normal left-sided system. These findings established the diagnosis of lymphatic plastic bronchitis due to thoracic duct agenesis. The patient declined lymphatic intervention aimed at occluding the subdiaphragmatic channels, and his condition remains chronically persistent.

conclusionThis case highlights an unusual and unexpected presentation of bronchial cast formation. While bronchial casts are typically identified and removed bronchoscopically-often preserving the morphology of the bronchial tree-in this patient the casts were not amenable to bronchoscopic removal, and were instead repeatedly expectorated as cohesive clots. Spontaneous expectoration of bronchial casts is a rare phenomenon and underscores the variability in clinical presentation and management challenges of this condition.