Clinico-pathological analysis referring hemeoxygenase-1 in acute fibrinous and organizing pneumonia patients.

Acute fibrinous and organizing pneumonia (AFOP) is a very rare pathological entity of lung injury characterized by intra-alveolar fibrin balls. Hemeoxygenase (HO) -1 is a cytoprotective enzyme against oxidative stress and inflammation. It is known to be expressed in the alveolar macrophages in the healthy adults and overexpressed in other various lung cells of the lung injury patients. We experienced two cases of subacute form AFOP for these 10 years and reviewed clinico-pathological characteristics. The average age was 62 years old and both were male. The etiology of both cases was idiopathic. The average PaO2/FIO2 ratio was 274.5 ± 84.1. The average levels of C-reactive protein and surfactant protein - A of the serum were elevated to 19.8 ± 6.3 mg/dL and 67.6 ± 15.8 ng/mL, respectively. Serum sialylated carbohydrate antigen levels were normal in both cases. The characteristic radiographic findings were bilateral consolidations and ground glass opacities. Lung biopsy specimens revealed fibrin balls and alveolitis with abundant cellular HO-1 expression. Steroid response was excellent and the pulmonary involvements absolutely disappeared for about 3 months.