Pathology-based evidence of association between adenovirus infection and appendicitis in children and adults

The main cause of appendicitis is obstruction of the appendiceal lumen. Obstruction can be caused by fecaliths or by swelling of nearby lymph nodes. Appendiceal obstruction can lead to poor blood circulation, bacterial growth, and tissue hypoxia, which can then cause appendiceal necrosis, peritonitis, sepsis, and even death. Studies have also associated appendicitis with lymphoid hyperplasia, which may be caused by infections such as adenovirus; however, direct evidence of this association is lacking. We retrospectively collected pathological records from 360 patients with appendicitis (240 adults and 120 patients aged younger than 18 years) and 40 control individuals without appendicitis. Appendectomy specimens were processed into formalin-fixed paraffin-embedded (FFPE) sections. Immunohistochemistry (IHC) and quantitative polymerase chain reaction (qPCR) analyses were used to determine the presence of adenovirus in appendiceal tissue samples. In pediatric patients, the adenovirus positivity rates obtained using IHC (25.8%) and qPCR (35.0%) were significantly higher than those in the control group (Fisher’s exact test P = 0.005 and 0.001, respectively). In adult patients, the adenovirus positivity rates obtained using IHC (10.8%) and qPCR (14.2%) were not significantly different from those in the control group (Fisher exact test P = 0.11 and 0.06, respectively). The IHC and qPCR results for the control group were all negative. Our study used retrospective pathological evidence (including IHC analysis and qPCR detection) to detect adenovirus in patients with appendicitis. qPCR seems to be better than IHC for the diagnosis of adenovirus infection in patients with appendicitis. The results also reveal that children with appendicitis are more likely to have adenovirus infection than adults with appendicitis.