I thank Dr Bowen for his letter, which I wish to respond to as follows:
Terminology.—Cast bronchitis has received several names over the years, including fibrinous, plastic, membranous, and pseudomembranous.
Plastic Bronchitis.—This is certainly an adequate term for this entity, although I find cast bronchitis more appropriate because it implies the formation of bronchial casts from the bronchial exudate. This characteristic distinquishes cast bronchitis from mucoid impaction (mucus plugs due to accumulated secretions).
Etiology.—Walker1 proposed the following causal classification for fibrinous bronchitis: A, primary; Aa, due to local causes, including tuberculosis, bronchial asthma, compression by mediastinal tumors, aneurysms, hypertrophic lymph nodes, and passive pulmonary congestion; Ab, due to general causes, including scarlet fever, influenza, and typhoid fever; and B, secondary. Hart and Meyer2 proposed a slightly different classification that included the following: (1) unknown origin; (2) infectious causes, including diphtheria and Pneumococcus; (3) disease