Table of Contents    
Year : 2015  |  Volume : 6  |  Issue : 2  |  Page : 476-479  

Enterobius vermicularis infestation masquerading as cervical carcinoma: A cytological diagnosis

Department of Pathology, ESIC Medical College and PGIMSR, Bengaluru, Karnataka, India

Date of Web Publication6-Jul-2015

Correspondence Address:
Dr. Kalyani Raju
H. No: 127/13, Sri Ganesh, 4th Main, 4th Cross, PC Extension, Kolar, Karnataka
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0976-9668.160047

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Although prevalence of Enterobius vermicularis (EV) infestation in Intestines ranges from 35% to 70%, its prevalence in female genital tract is not known despite several incidental findings. Acute inflammatory cells in the background of cervical Pap smear indicate infestation and should not be neglected as contamination. A 40-year-woman presented with white vaginal discharge persistent for past 1 year. Local examination showed hypertrophied cervix with eversion of both lips and hard consistency of the anterior lip of cervix. A clinical diagnosis of cervical carcinoma was made. However, cervical Pap smear indicated EV eggs in an inflammatory background, treatment to which resulted in completely recovery.

Keywords: Cervical smear, Enterobius vermicularis, pap smear

How to cite this article:
Raju K, Verappa S, Venkataramappa SM. Enterobius vermicularis infestation masquerading as cervical carcinoma: A cytological diagnosis. J Nat Sc Biol Med 2015;6:476-9

How to cite this URL:
Raju K, Verappa S, Venkataramappa SM. Enterobius vermicularis infestation masquerading as cervical carcinoma: A cytological diagnosis. J Nat Sc Biol Med [serial online] 2015 [cited 2021 Apr 13];6:476-9. Available from:

   Introduction Top

0Enterobius vermicularis (EV)/pin worm is a common helminthic parasite in intestines and is rarely observed in unusual sites. [1],[2],[3] Detection of EV in vagina or  Pap smear More Details is although unusual but is previously reported. [1]

Enterobius vermicularis infection is usually asymptomatic. [4] Pap test that is routinely used to detect epithelial abnormality can sometimes detect EV infections, evident by presence of characteristic cytomorphology of the eggs thus necessitating appropriate treatment. [5] The cytological/histopathological differential diagnosis are other parasitic ova, pollen grains, contaminated vegetable cells and fungal spores. [1],[6]

   Case Report Top

A 40-year-old -woman presented with white discharge per vagina since 1 year. Per-speculum examination showed hypertrophied cervix with eversion of both lips. Per-vaginal examination revealed hard consistency of the anterior lip of cervix. A provisional clinical diagnosis of cervical cancer was made. With the consent of the patient, conventional Pap smear was taken and stained with Pap stain. Pap smear was satisfactory for evaluation, showed endocervical cells as junctional component; clue cells were present and background showed neutrophils and coccobacilli. Two focal areas showed 2-3 eggs of EV that was oval/elongated in shape, flattened on one side, measured approximately 50μ × 25μ, had double contoured birefringent yellow to orange shell with coiled larvae within it [Figure 1] and [Figure 2]. Despite no significant history or family members having EV infestation and no signs/symptoms of oxyuriasis, cellophane tape test performed 5 times at different intervals did not show evidence of active parasitic disease. Patient was not immuno-compromised. Hence the diagnosis of the inflammatory smear with bacterial vaginitis and EV infestation was made. Patient responded well with antibiotics and anthelmintics and was symptom-free posttreatment for 1 year follow-up.
Figure 1: Microphotograph showing eggs of Enterobius vermicularis in a background of neutrophilis (Pap, ×100)

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Figure 2: Microphotograph showing eggs of Enterobius vermicularis with thick sheath and larva inside (Pap, ×400)

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   Discussion Top

0Enterobius vermicularis is the most prevalent human nematode worldwide. [1],[3],[7] The prevalence of intestinal enterobius ranges from 35% to 70%. However, the prevalence in female genital tract (FGT) is not known as only a few case reports are published. EV in FGT is uncommon and is usually found as an incidental finding in routine Pap test, at surgery or at autopsy without signs/symptoms or evidence of active parasitization. [1],[2],[4] In our case, it was an incidental finding in Pap smear.

The mode of infection is by direct ingestion of infected eggs by anus to mouth contact, contact with an infected person or contaminated objects. Indirect transmission occurs through airborne eggs dislodged from contaminated clothing or bed linen and inhaled with dust. [1],[2],[7] The ingested eggs hatch and release larvae in small intestine and adult worm reside in caecum and colon. The adult female worm once fertilized descends into rectum and migrate to perianal and perineal region during the night usually in children. In female patients sometimes it enter vagina and lay eggs that mature in a few hours into fully developed infectious larvae. Self-infestation also occurs by retro-infection that is however not the usual route. The worm can migrate into cervix, endometrium,  Fallopian tube More Details and may enter peritoneal cavity giving rise to vulvovaginitis, cervicitis, endometritis and salpingitis involving all organs of FGT. [1],[2],[4],[7] Peritoneal involvement has also been reported to happen by penetration of the gastrointestinal tract with preexisting disease especially in males. [2],[4] Other rare ectopic locations reported especially for female EV are prostate, urinary bladder, ureter, spleen, intestinal wall, liver, lungs, epididymis and conjunctival sac where diagnosis is possible only by histology. [7]

Less than 30% of reported cases have clinical signs/symptoms such as perianal itching to severe life-threatening illness including fatalities in primates. The nongastrointestinal signs/symptoms are pruritus vulvae, urinary tract infection, vaginal discharge, postmenopausal bleeding, epididymitis, pelvic mass, tubo-ovarian abscess, salpingitis and generalized peritonitis by parasite/eggs. [1],[2],[4] In the present case, the patient presented with white discharge per vagina for 1 year.

In Pap smear presence of eggs with acute inflammatory cells in the background indicate infestation and should not be neglected as sampling contamination. [2],[4] The EV is diagnosed cytologically by the characteristic morphology of eggs because adult parasites are usually degenerated. The size of eggs is 55-60 μ in length and 25-30 μ in width and are flattened on one side. It has thick double birefringent refractile sheath containing larvae that appear granular or as curved structure. Sometimes empty shadow eggs or wrinkled shell enclosing clumped granular material are also observed. [1],[2],[4],[8] The lesions of EV is usually superficial granulomas with variable necrosis and fibrosis along with diagnostic eggs, granulation tissue, acute inflammation and sometimes degenerated adult parasite. Ova are considerably more resistant than the worm. The parasite usually presents as surface lesion and does not invade normal tissue. However, it may be seen in ovarian parenchyma where parasitization occurs immediately following rupture of the ovarian follicle. Multiple histologic sections are required in case of older fibrous lesions as a result of the inflammatory response to dead adult female worm. Usually, the cytology/histopathology finding is incidental. [4],[7] The active disease can be evaluated by cellophane/scotch tape for 5 times on separate days. Peripheral blood smear may show eosinophilia. [2],[4] In this case report, the Pap smear showed EV eggs having characteristics features. Surprisingly there was no evidence of either active disease or blood eosinophilia.

The differential diagnoses are the endometritis, salpingitis, appendicitis and peritonitis due to various causes. The granuloma of different etiology in FGT forms differential diagnosis. If the lesion presents as a mass, the differential diagnosis is either neoplasm or metastatic deposits, [4],[3],[7] Two case reports are published in which the lesion resembled metastatic deposits in ovary in a case of in situ squamous cell carcinoma of the cervix. [4] The parasites which form a differential diagnosis are Entamoeba histolytica, Microfilaria, Strongyloides stercoralis, Schistosoma haematobium, Trichuris trichiura, Ascaris ova and Tenia eggs. Pollen grains, vegetables and fungal spores may also be intrinsic or extrinsic sample contaminations. Pollen grains microscopically have two layers with grains enclosed inside. [1],[6] Although enterobiasis is of low pathogenicity, complication due to microbic co-infection occur as bleeding, infertility, tubo-ovarian abscess and generalized peritonitis. [3],[7],[9] In our case, the provisional clinical diagnosis was carcinoma cervix, probably because of tissue changes due to chronic EV infestation and associated bacterial infection.

To conclude, diagnosing unusual infection in Pap smear is challenging but can be valuable to initiate appropriate therapeutics. Clinical awareness and knowledge of cytomorphology of this unusual entity is important in certain cases of vaginitis/cervicitis for accurate diagnosis and initiate proper treatment.

   References Top

Shetty JB, Kulkarni DV, Prabhu V. Eggs containing larvae of Enterobius vermicularis in vaginal smear. J Cytol 2012;29:94-6.  Back to cited text no. 1
[PUBMED]  Medknow Journal  
Kyu Choi S, Kyung Kim E, Hong YO, Ho-Jung Lee, Won-Mi Lee, Sook-Kyung Ko, et al. Enterobius vermicularis ova in a vaginal smear. Korean J Pathol 2010;44:341-2.  Back to cited text no. 2
Powell G, Sarmah P, Sethi B, Ganesan R. Enterobius vermicularis infection of the ovary. BMJ Case Rep 2013;2013.  Back to cited text no. 3
McCabe K, Nahn PA, Sahin AA, Mitchell MF. Enterobiasis of the ovary in a patient with cervical carcinoma in situ. Infect Dis Obstet Gynecol 1995;2:231-4.  Back to cited text no. 4
Khalbuss WE, Michelow P, Benedict C, Monaco SE, Pantanowitz L. Cytomorphology of unusual infectious entities in the Pap test. Cytojournal 2012;9:15.  Back to cited text no. 5
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Martínez-Girón R, Ribas-Barceló A, García-Miralles MT, López-Cabanilles D, Tamargo-Peláez ML, Torre-Bayón C, et al. Airborne fungal spores, pollen grains, and vegetable cells in routine Papanicolaou smears. Diagn Cytopathol 2004;30:381-5.  Back to cited text no. 6
Pampiglione S, Rivasi F. Enterobiasis in ectopic locations mimicking tumor-like lesions. Int J Microbiol 2009;2009:642481.  Back to cited text no. 7
Mehrotra S, Young SL, Wojcik EM. Brown oval structures in vaginal Thin Prep smear: What could they be? Diagn Cytopathol 2007;35:651-2.  Back to cited text no. 8
Craggs B, De Waele E, De Vogelaere K, Wybo I, Laubach M, Hoorens A, et al. Enterobius vermicularis infection with tuboovarian abscess and peritonitis occurring during pregnancy. Surg Infect (Larchmt) 2009;10:545-7.  Back to cited text no. 9


  [Figure 1], [Figure 2]

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