Enterobius vermicularis as a Mimic of Acute Appendicitis: A Case Report and Updated Systematic Review.

A 12-year-old premenarchal female patient presented with right iliac fossa pain, perianal pruritus, urticaria, angioedema, arthralgia, peripheral eosinophilia, and an initially undetectable C-reactive protein. Serial ultrasonography demonstrated increasing intra-abdominal free fluid. Diagnostic laparoscopy demonstrated appendiceal serosal injection, turbid pelvic fluid, and mesenteric lymphadenopathy, prompting appendectomy. Histopathology identified Enterobius vermicularis (EV) within the appendiceal lumen, with reactive lymphoid hyperplasia but no acute suppurative inflammation. Symptoms resolved following surgery and mebendazole treatment. A descriptive updated systematic review of appendectomy specimens containing EV was performed. Seventy-six studies comprising 196,138 appendectomy specimens were included. EV was identified in 3,913 specimens, corresponding to a crude proportion among appendectomy specimens of 2.00% (95% CI: 1.93-2.06%). Among 11 newly identified studies reporting histological subclassification, 247 of 694 EV-positive specimens (35.6%) demonstrated histological acute appendicitis, whereas most showed non-suppurative or reactive pathology. This case and review suggest that appendiceal enterobiasis may present as an appendicitis-like illness, particularly when abdominal pain occurs alongside atypical features such as perianal pruritus, eosinophilia, urticaria, or angioedema. Recognition of enterobiasis may guide anthelmintic therapy and consideration of household treatment; however, a causal relationship between EV and systemic hypersensitivity features cannot be established from a single case. Importantly, clinical deterioration should continue to prompt urgent surgical assessment.