Enterobius vermicularis infection of the liver in a patient with colorectal carcinoma with suspected liver metastasis

[Multilocular hepatic masses due to Enterobius vermicularis]

Infestation with Enterobius vermicularis involving extraintestinal manifestation is rare. In a 50-year-old man with lower abdominal pain, computed tomography led to a suspected diagnosis of sigmoid carcinoma with liver metastasis. After ruling out colon cancer by endoscopy, laparoscopic resection of one suspected tumor nodule in the liver was performed. Histopathological examination revealed parasitic granulomas containing pinworms. Hematogenous migration was postulated in the setting of phlebitis with thrombosis of the inferior mesenteric vein.

Hepatic pinworm infestation misdiagnosed as a liver metastasis in a patient with colonic adenocarcinoma

An extra-intestinal infestation of Enterobius vermicularis (pinworm) is uncommon. We present a case of hepatic infestation of pinworm in a 57-year-old woman, misdiagnosed as a colorectal adenocarcinoma metastasis. The route of migration from the intestine to the liver is not well established but the most plausible route seems to be hematogenous. In concordance with previously published cases, the hepatic pinworm infestation is usually localised superficially in the right liver lobe. Hence solitary lesions in this location detected radiologically should be interpreted carefully. Additionally, the serum CEA level could be useful to distinguish pinworm from malignancy.

The Diagnosis and Treatment of Pinworm Infection

BACKGROUND

Symptomatic infection with pinworm (Enterobius vermicularis), a human pathogen, is clinically relevant in Germany, with an estimated prevalence in childhood of 2-20%. Enterobiasis can cause major mental distress. There is little systematically verified knowledge on the treatment of this condition, and there is no corresponding German guideline. This review is, therefore, intended as a summary of the current state of knowledge.

METHODS

This review is based on pertinent publications retrieved by a selective search in PubMed for literature appearing from 1 January 1990 to 5 February 2019 and containing the search terms "enterobiasis," "oxyuriasis," "Enterobius vermicula- ris," "pinworm," and "threadworm."

RESULTS

More than one billion people worldwide are thought to be infected with pinworm. Estimates of its prevalence among kindergarten and primary-school pupils in Europe are generally near 20%. Infants (<2 years of age), adolescents (>14 years of age), and adults are only sporadically affected. The main risk factors are age 4-11 years, uncontrolled anus-finger-mouth contact, nail-biting (onychophagia/peri- onychophagia), unsupervised body hygiene, and poor compliance with basic hand hygiene. No large-scale, randomized, controlled trials of treatment are available. The approved antihelminthic agents are mebendazole, pyrantel embonate, and pyrvinium embonate (success rates up to >90%). For recurrent infections, prolonged treatment for up to 16 weeks (a "pulse scheme") is recommended.

CONCLUSION

In nearly all cases, antihelminthic treatment along with attention to hygienic measures can successfully eradicate pinworm infection and prevent recurrence and autoinfection. The involvement of all persons living in the patient's house- hold, including sexual partners, is a prerequisite to the lasting success of treatment.