In addition, the serum HMGB1 level of children with perforated appendicitis was higher than that of those without perforation,65 which was consistent with the findings of previous studies in adult AA patients,66, 67 suggesting that serum HMGB1 may be implicated in the severity of AA and is an important biomarker for the diagnosis of AA, especially for patients with normal WBC counts. Here, HMGB1 is linked to appendicitis.