A tissue sample of 1 cm3 that focused on a macroscopic lesion was fixed in formalin and embedded in paraffin. Five-micrometer sections were obtained and colored with hematoxylin and eosin. After viewing five fields per sector in a blinded manner, each section was assigned a numerical histologic score ranging from 0 to 3 according to the degree of PMN infiltration, hemorrhage, and edema in the interstitial and alveolar spaces .