Secondary organizing pneumonia following viral pneumonia caused by severe influenza B: a case report and literature reviews

Abstract

Background: Some reported that organizing pneumonia (OP) may occur after influenza A infections including swine-origin influenza A (H1N1). However, OP associated with influenza B infection has never been reported. We report the first case of secondary OP associated with viral pneumonia caused by influenza B.

Case presentation: A 23-year old woman was diagnosed as viral pneumonia caused by type B influenza. Despite of antiviral therapy, abnormal chest shadows were not improved. Bronchoscopy and transbronchial lung biopsy showed organizing pneumonia due to viral pneumonia caused by influenza B. Corticosteroid therapy was started at 30 mg daily (0.5 mg/kg), and the dose was reduced to 25, 20, 15 or 10 mg per day every month with symptomatic and radiological resolution. Even after corticosteroid therapy was discontinued, we did not confirm disease recurrence.

Conclusions: Physicians should be aware of the possibility for SOP and severe viral pneumonia even in case of type B as well as type A influenza infections.

Keywords: Influenza pneumonia; Organizing pneumonia; Type B influenza virus.

Fig. 1

Chest X-ray showed bilateral infliltrates on admission (a upper). After starting PSL therapy on day 25, infiltrates were improved (b upper). Abnormal shadows on Chest X-ray disappeared 6 months after starting corticosteroid therapy (c upper). Chest CT showed consolidations on both lungs on admission (a lower) and the shadows were improved on day 25 after starting corticosteroid therapy (b lower). Six months after starting corticosteroid therapy, the consolidations disappeared (c lower)

Fig. 2

TBLB specimen from the right middle lobe showed intraalveolar granulation tissue with myofibroblasts consistent with organizing pneumonia (Hematoxin-Eosin (HE) × 100) (a). Masson body (red arrow) was seen on the TBLB specimen (HE ×400) (b)