A 16-Year-Old Female With Right Lower Quadrant Abdominal Pain

Diagnosis: Enterobius vermicularis appendicitis. The appendectomy specimen showed an intraluminal parasite with lateral alae characteristic for Enterobius vermicularis (Figures 1 and 2). The appendix showed submucosal lymphoid hyperplasia but no acute inflammation. Postoperatively, the patient and her family members received a course of albendazole. Appendicitis is the most common abdominal surgical emergency [1]. Appendectomy is not always the final cure for this condition and some specific postoperative treatment might be warranted. Fecaliths and submucosal inflammation, believed to be caused by viruses, account for 80%–95% of cases [1]. Less common causes for inflammation of the vermiform appendix include foreign bodies, neoplasm, and inspissated barium from radiological studies. Fruit seeds, parasites, and calculi are considered foreign bodies and account for about 4% of all cases of appendicitis. Parasitic appendicitis requires a high index of suspicion and can easily be overlooked in low-prevalence regions [2]. It is usually diagnosed intraoperatively or on histopathological examination. The most commonly reported causative parasites are E. vermicularis, Ascaris lumbricoides, Entamoeba histolytica, and Giardia species [2]. The prevalence of the pinworm E. vermicularis infestation ranges between 0.6% and 13% [3].Children are most commonly affected [4]. Persons at risk include those in direct contact with infected individuals and institutionalized subjects. Colonization begins with the ingestion of parasitic eggs from contaminated meals, contact with colonized individuals, or fomites [3]. The eggs can survive in open environments for approximately 15–20 days and are resistant to chlorinated water (eg, swimming pools). This resiliency permits eggs’ survival in places such as fingernails, clothing, house dust, and other surfaces [3]. Following ingestion, hatching occurs upon the eggs’ reaching the duodenum, and the worms molt twice before they migrate to the cecum and ascending colon. They develop into an adult worm in 5–6 weeks and live for 1 month. Upon mating, gravid females migrate to the rectum; during the night, egg-laden females exit the anal canal and deposit