Appendix - Enterobius vermicularis

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Appendix

Appendicitis

Enterobius vermicularis

Reviewer: Jaleh Mansouri, M.D. (see Reviewers page)
Revised: 8 March 2013, last major update August 2012
Copyright: (c) 2003-2012, PathologyOutlines.com, Inc.

General
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● Also known as pinworm
● Formerly known as oxyuris vermicularis, oxyuriasis
● Most common helminthic infection in children, affects all social strata in the US

Clinical features
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● Usually more common in temperate climates
● Usually found in appendix of children ages 7-11 years as incidental finding
● Mass of worms may cause obstruction
● May occasionally be associated with appendicitis (Pediatr Surg Int 2004;20:372, Southeast Asian J Trop Med Public Health 2007;38:20)
● Eggs often deposited at night on perianal skin, causing pruritis ani, irritability, loss of sleep (DPDx - Enterobiasis)
● Eggs can be diagnosed with the cellulose tape technique on perianal skin when child wakes up
● Adult worms may migrate to the lower genital tract and cause a granulomatous reaction

Case reports
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● 33 year old woman with clinical appendicitis (Case of the Week #90)

Gross description
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● Worms reside in cecum, 1.3 cm long

Micro description
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● Cross section has narrow lateral cuticular alae

Micro images
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Pinworm and eggs

Eggs

Enterobius in appendix

Cytology images (urine)
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Ova and larva of Enterobius vermicularis

Differential diagnosis
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● Vegetable matter, whipworm

End of Appendix > Appendicitis > Enterobius vermicularis

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