A usual parasite in an unusual location- Incidental detection of Strongyloides stercoralis in liquid-based cytologyPM Sundar1, S Sivanandam1, TV Chitra2
1 Department of Pathology, PSG Institute of Medical Sciences and Research, Coimbatore, Tamil Nadu, India
2 Department of Obstetrics and Gynecology, PSG Institute of Medical Sciences and Research, Coimbatore, Tamil Nadu, India
Correspondence Address: Source of Support: None, Conflict of Interest: None DOI: 10.4103/jpgm.jpgm_614_21
Source of Support: None, Conflict of Interest: None
We report the case of a 62-year-old woman who was admitted to our institution for laparoscopic cholecystectomy and para-umbilical hernia repair. She had complaints of leucorrhea, burning micturition, and two episodes of hematuria on admission. Urology and gynecology opinion was sought. Urological examination and computed tomography of the abdomen revealed no abnormalities. On per speculum examination, the cervix was congested. Mild cystocele and second-degree descent of the cervix were observed. A liquid-based Pap test was suggested as a part of the workup.
Double smears were made on a single precoated slide using the EziPREPTM liquid-based cytology (LBC) technique. On microscopic examination, the LBC smears were moderately cellular with abundant inflammatory cellular infiltrates. The exfoliated cells were atrophic squamous epithelial cells and the inflammatory infiltrate was composed of neutrophils admixed with eosinophils. Also seen were 15 larvae of Strongyloides stercoralis [Figure 1]. The larvae were short, curved, and thick at low magnification (10×). At higher magnification (40×), a stout/blunt anterior end reminiscent of the buccal cavity and a pointed posterior end/tail with a deep purple core was observed [Figure 2]. On inquiry, past history of on and off abdominal pain with bowel disturbances was elicited. The stool examination ordered was negative for larvae of S. stercoralis. The patient was treated with a course of ivermectin and is currently doing well.
Cervical strongyloidiasis is a rare occurrence, owing to its natural life cycle. There are only seven reported cases of cervical strongyloidiasis in the world.,,,,,, In each of the previous reports, except for one isolated report in 2017 from India, only single larvae of S. stercoralis were identified in the cervical smear. In all these reports, the larvae were identified in conventional Pap smear. Ours is the first report of S. stercoralis detected by LBC technique and the first to report multiple larvae (15) in a cervical smear. Detection of this parasite in the cervical smear could be due to the migration of the larvae from the perianal skin to the cervix. In the present case, the patient could have had a chronic infection, which may have gone undetected and now presented with autoinfection.
S. stercoralis can be mistaken morphologically for other parasites in cervical cytology such as hookworm and microfilariae. Hookworm larvae closely resemble rhabditiform larvae of S. stercoralis and can be differentiated from the former by a short buccal cavity and prominent genital primordium. The filariform larvae, in contrast, have a notched tail compared to hookworm larvae. The diagnosis of strongyloidiasis is challenging because most people are asymptomatic and the available fecal-based screening or serological tests have varied sensitivity. This could explain the negative stool result in the present patient.
In conclusion, this case snippet is presented here to serve as an important clinical reminder about this under-diagnosed disease. Lack of familiarity with such unusual presentations, the morphology of the parasite, and lack of a high index of suspicion for strongyloidiasis, especially in endemic regions, can result in misdiagnosis. An incorrect diagnosis of even a mild infection with S. stercoralis can result in long-term serious consequences, especially if the affected individual becomes immunocompromised or undergoes immunosuppressive therapy.
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[Figure 1], [Figure 2]