Examination methods
The removed tonsils immersed in 10% formalin solutionwere divided into parts passing through the upper and lower pole, and were fixed in a paraffin block by the same operator. The paraffin block-was made into 4-5 micron sections and stained with hematoxylin–eosin method. The pathological section was photographed by KF-PRO-120 digital pathology panoramic scanner(KFBIO,Yuyao,China), and the necrosis depth was measured by K-Viewer software(KFBIO,Yuyao,China).