Clinical and Immunohistochemical Evaluation of Acute Interstitial Pneumonia, Bronchiolitis Obliterans Organizing Pneumonia, and Acute Exacerbation of Idiopathic Pulmonary Fibrosis.

Abstract

Acute interstitial pneumonia (AIP), bronchiolitis obliterans organizing pneumonia (BOOP), and acute exacerbation of idiopathic pulmonary fibrosis (IPFex) all present with acute onset and a rapidly progressive clinical course. Since it is sometimes difficult to differentiate among these three entities, the present study was designed to analyze differences. Four AIP, seven BOOP, and eight IPFex patients were studied clinically and pathologically with semi-quantitative scoring methods using immunohistochemistry. Clinically, there were no significant differences, except that the patients with BOOP had lower chest roentgenogram scores and lung injury scores (p < 0.05 ). Pathologically, the mean epithelial basement membrane damage score in the AIP patients was higher than that of the other patients (p <0.05). Among the intraluminal organizing exudate scores, the polypoid type was highest in the BOOP patients (p <0.01), and the incorporative/obliterative type was highest in the AIP patients (p < 0.005). The epithelial basement membrane damage scores correlated with the intraluminal organizing exudate scores (polypoid type, r = -0.57 ; incorporative/obliterative type, r = 0.81). Although there are clinical similarities among the three disorders, pathological differences also exist and are demonstrated by the present findings.