Plastic bronchitis associated with influenza B virus infection: A case report.

Plastic bronchitis (PB) is a severe acute respiratory disease that develops as a result of the formation of branching mucus plugs in the bronchial tree. PB is known as a complication of influenza A virus infection, but some cases have been associated with influenza B virus infections. This patient was a 3-year-old boy with no history of allergic disease who developed PB requiring ventilator management after influenza B virus infection. He was hospitalized and managed with ventilator support because of acute respiratory failure. Influenza B virus infection was diagnosed via rapid antigen test and real-time reverse-transcription polymerase chain reaction (RT-PCR). A bronchoscopy performed after a chest X-ray and computed tomography confirmed the presence of extensive atelectasis in the right lung field and mucus plugs in the right bronchus. The patient's respiratory condition improved rapidly after removal of the plugs. Quantitative real-time RT-PCR performed with nasal and aspirated sputum samples obtained at hospitalization revealed a higher viral RNA load in the upper rather than in the lower respiratory tract. Viral replication in the lower respiratory was not found to be a major contributor toward mucus plug formation. The finding of increased serum IgE in the absence of a history of allergic disease suggests that an allergic reaction contributed to the formation of mucus plugs.