Differential diagnosis and management for perforated appendicitis and non-perforated appendicitis are current hot topics. The aim of this study is to demonstrate a new entity of non-perforated appendicitis, "acute hemorrhagic appendicitis" through studying cluster of acute appendicitis among Tibetan students at a high school in central China. Over the 11-year period, there were 120 patients with more female patients (102 of 499, 20.4%) than male patients (18 of 474, 3.8%) among 973 Tibetan students. 117 patients' clinical data were available. Clinical manifestations were identical to classic appendicitis. However, axilla temperature, white blood cell counts and neutrophil level were elevated mildly in 12 (10.3%), 19 (16.2%) and 12 (10.3%) patients respectively. Pathologically, the resected appendices exhibited focal or diffuse hemorrhages in mucosa and/or submucosa, and infiltration by eosinophil and by lymphocytes. No patients had perforated appendicitis. The median time from the onset to surgery was 3 days (IQR, 2-4). All patients were discharged with full recovery. In conclusion, "acute hemorrhagic appendicitis" represented a new entity of non-perforated appendicitis with unique cause and pathogenesis, which might be treated with antibiotics alone or self-limited. Studying the cluster is a reliable method to find new entity of appendicitis.
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