Organizing pneumonia in patients with severe respiratory failure due to novel A (H1N1) influenza

Abstract

The authors describe two cases that developed organizing pneumonia (OP) associated with novel influenza A(H1N1) virus. These patients were admitted to intensive care unit (ICU) because of severe respiratory failure. After initial clinical improvement, both patients worsened their condition during their second week of ICU stay, presenting fever, increasing in inflammatory parameters and worsening in oxygen exchange and respiratory mechanics. Chest x-rays and computed tomographies showed an increment on lung infiltrates, given by areas of consolidation and ground glass opacification. Although broad-spectrum antibiotics were administered, patients showed no improvement. All cultures, including bronchoalveolar lavage samples, were negative. In both cases, an open lung biopsy was performed, and histopathological examination of the specimen was compatible with OP. Both patients were successfully treated with high-dose corticoids. The aim of this report is to alert about the possibility of OP associated with novel influenza virus in patients with severe respiratory failure.

Figure 1

Chest CT taken at ICU admission show diffuse ground glass opacities with some peripheral and peribronchovascular lobular consolidation. Chest CT taken before lung biopsy show foci of ground glass have evolved to bilateral consolidations, predominantly in a subpleural peripheral distribution. Areas of ground glass opacities have appeared in both upper lobes (not shown in these pictures). In left lower lobe, ground glass opacities has been replaced by fine reticular intralobular opacities with traction bronchioloectasis (suggesting initial fibrosis).

Figure 2

Histopathological findings in Case 1(A) Sparse intraalveolar areas of fibrin accumulation (Masson bodies) and organizing pneumonia. (B) Solid area with bronchiolar necrosis and reparative changes, squamous metaplasia and type II alveolar hyperplasia. (C) Organizing pneumonia involving 75% of the alveolar spaces in the lung parenchyma.

Figure 3

Chest CT taken at ICU admission show extensive areas of ground glass opacities and air space consolidation. Chest CT taken before lung biopsy show decrease of ground glass opacities in middle right lobe, and progression of consolidation in left lower and lingule. In addition, loss of global lung volume is observed.

Figure 4

Histopathological findings in Case 2.(A) Mild interstitial inflammatory lymphoplasmacytic cell infiltrate and sparse fibrin accumulation intraalveolar. (B) Solid area of prominent organizing pneumonia and athelectasia. (C) Intraalveolar oedema and haemorrhage admixed with macrophages and Masson bodies.