Clinical Quiz

Abstract

A healthy 15-year-old girl was referred to our Centre with two episodes of painless fresh rectal bleeding each lasting for a few days. The blood was not mixed with stool. Stools were described as normal and there was no recent change in her bowel habits. There was no abdominal pain or other symptoms referable to the GI tract. Her father had a similar problem that he attributed to hemorrhoids. Physical examination was normal. She had routine investigations including complete blood count, blood urea nitrogen and serum electrolytes, liver function tests and inflammatory markers. All were within normal values. Colonoscopy was performed and biopsies taken. The histopathology of transverse colonic biopsy is shown in (Fig. 1).FIG. 1: Transverse colonic biopsy histopathology.What is the diagnosis? Ulcerative colitis. Rectal polyp. Enterobius vermicularis infestation. Meckel's diverticulum. ANSWER C. Enterobius vermicularis (Threadworm) Infestation. Figure 2 shows a segment of colonic mucosa. The surface epithelium is intact with mild patchy mucus-cell depletion. The lamina propria is edematous with a moderate increase in chronic inflammatory cells, especially eosinophils. One E. vermicularis worm is present (Fig. 2, arrow). The patient was treated with a single dose of albendazole that was repeated after 2 months. The patient made a full recovery with no further rectal bleeding.FIG. 2A: segment of colonic mucosa. One Enterobius vermicularis worm is present (arrow).Enterobius vermicularis is a nematode with worldwide distribution, although it is most prevalent in temperate and cold climates. Children are most often infected, but infestation can spread rapidly among family members. Infection spreads by direct transmission of ova from person to person or indirectly on clothing or house dust (1). Although nocturnal anal pruritus is usually the most common presenting symptom, there have been a few reports of E. vermicularis-induced eosinophilic colitis presenting with bloody diarrhea (2,3). Ova can be detected in the perianal region by applying a clear adhesive tape to the perianal skin and examining this microscopically. A single oral dose of albendazole is the treatment of choice, although pyrantel pamoate and piperazine are also effective. Treatment of the entire family is usually indicated (4). A second dose might be needed, as re-infestation can occur as early as 2 months after initial treatment (1).