Plastic bronchitis (PB) is a disorder in which branching casts of the airways are expectorated. PB is not a single disease with a defined mechanism that explains the cast formation in all conditions. Examples of diseases associated with expectoration of casts, and which sometimes are labeled PB include tuberculosis, atypical mycobacterial disease, allergic bronchopulmonary aspergillosis, and asthma. When casts are very large with many branches, an abnormal communication or leakage of lymphatic fluid into the airway is often the cause. This entity is termed lymphatic plastic bronchitis (LPB). LPB is a lymphatic flow disorder characterized by the recurrent formation of branching, rubbery bronchial casts composed primarily of proteinaceous and sometimes chylous material and lymphocytes. Lymphatic fluids deposited into the airspaces become gelatinous as they cool, forming large string cheese-like casts of the airways, which can obstruct airflow. Attempts to expectorate casts can be quite frightening, leading to fears of asphyxiation. Signs and symptoms
The clinical presentation of plastic bronchitis beyond expectoration of casts includes a productive cough, dyspnea, fever and wheezing. Focal wheezing is a characteristic, if not specific, physical examination finding. If the casts completely obstruct the airway, breath sounds will be decreased and dullness will be present with percussion. With partial obstruction, a “fan sound” or “flag flapping” sound can be heard during auscultation. Bronchial casts can sometimes fill the airways of almost an entire lung, and present as an acute, life-threatening emergency. Pathology
The majority of PB cases are associated with an underlying disease.
Inhaled mucolytics: Potassium iodide and acetylcysteine inhaled therapy are often used to help the patient cough up the casts by breaking down the thick mucus formations. Inhaled and oral steroids: If PB is associated with asthma or an infection, inhaled and oral steroids have been shown to be effective. Prognosis
Patients with plastic bronchitis that is being caused due to a co-morbid condition generally have a good prognosis once the underlying disease is treated. Epidemiology
To date, about 420 cases have been reported in the medical literature. Given its unusual nature, the true prevalence of PB is unknown, and it is likely that many patients are undiagnosed. PB does affect patients of all age groups and genders. == References ==