Incidental detection of Wuchereria bancrofti in a Liquid-based cytology smear coexisting with ovarian serous cystadenoma and bilateral hydrosalpinx: A rare case report

Background: Lymphatic filariasis, caused predominantly by W. Bancrofti , remains a significant public health concern in several parts of India, including Bihar. Although microfilariae are commonly found in peripheral blood and lymphatic tissues, their detection in cervicovaginal cytology smears is extremely rare and is usually an incidental finding during routine cervical cancer screening. Case Presentation: A 50-year-old multiparous woman (P3L3) presented with abnormal uterine bleeding (AUB-A). Ultrasonographic evaluation showed adenomyosis with hydrosalpinx .A Liquid-Based Cytology (LBC) Pap smear revealed sheathed microfilariae and was reported as Negative for Intraepithelial lesion or malignancy (NILM) with presence of organism consistent with morphological features of W. Bancrofti . The patient subsequently underwent vaginal hysterectomy with bilateral adnexal remo val, and histopathological examination revealed a right ovarian serous cystadenoma and bilateral hydrosalpinx. No adult filarial worms were identified in the surgical specimen.

This case highlights the diagnostic value of meticulous cytological screening, particularly in filariasis-endemic regions. The incidental detection of microfilariae in an otherwise NILM smear, along with the coexistence of ovarian serous cystadenoma and bilateral hydrosalpinx, underscores the importance of maintaining a hi gh index of suspicion for occult parasitic infections during routine cytological evaluation.

W. Bancrofti , Microfilaria, Liquid -Based Cytology, Pap smear, Serous cystadenoma, Hydrosalpinx, Occult filariasis

Lymphatic filariasis is a mosquito -borne parasitic disease that continues to pose a major public health challenge in tropical and subtropical regions. Among the filarial parasites infecting humans, W. ( Wuchereria) Bancrofti is responsible for nearly 90% of cases worldwide. India contributes substantially to the global disease burden, with several states, including Bihar, remaining endemic despite ongoing elimination programs [1]. In humans, adult worms reside within lymphatic vessels, whereas microfilariae circulate in the peripheral blood, characteristically exhibiting nocturnal periodicity [2]. Cervicovaginal cytology is routinely employed for the screening of premalignant and malignant cervical lesions. In addition to epithelial abnormalities, a variety of infectious agents may occasionally be identified in cervical smears [3]. However, the presence of microfilariae in cervicovaginal cytology is exceptionally rare because the female genital tract is not a natural habitat for the parasite. Consequently, most reported cases represent incidental findings detected during routine cervical screening [4]. The exact mechanism responsible for the appearance of microfilariae in cervicovaginal smears remains uncertain. Proposed explanations include lymphatic obstruction, rupture of superficial lymphatic vessels, and inflammatory damage leading to the extravasation of microfilariae into surrounding tissues [5]. Although filariasis has been described in association with both benign and malignant gynecological conditions, its coexistence with adnexal lesions is uncommon and remains a diagnostic curiosity. A review of the literature reveals only a limited number of case reports and small case series describing microfilariae in cervicovaginal smears. Herein, we report a rare case of incidental International Journal of Clinical Obstetrics and Gynaecology https://www.gynaecologyjournal.com ~ 2526 ~ detection of W. Bancrofti microfilariae in a Liquid -Based Cytology (LBC) Pap smear from a patient presenting with abnormal uterine bleeding. Histopathological examination subsequently revealed a right ovarian serous cystadenoma and bilateral hydrosalpinx, making this an unusual coexistence of occult filarial infection with benign adnexal pathology. Case Presentation A 50 -year-old multiparous woman (P3L3) presented with abnormal uterine bleeding (AUB -A). She had a history of three full-term normal vaginal deliveries and had undergone bilateral tubal ligation eight years earlier. On examination, the abdomen was soft and non -tender with no palpable mass. Per speculum examination revealed a hypertrophied cervix with erosions around the external o s and whitish discharge, while per vaginal examination showed a mildly bulky anteverted uterus with free bilateral fornices. Laboratory investigations revealed mild anemia (hemoglobin 9.8 g/dL) with eosinophilia. Peripheral blood smear showed normocytic no rmochromic anemia and mild eosinophilia but was negative for hemoparasites. Serological tests were non - reactive. Ultrasonography suggested adenomyosis with bilateral hydrosalpinx, more prominent on the left side. A Liquid -Based Cytology (LBC) Pap smear was reported as negative for intraepithelial lesion or malignancy (NILM). However, careful microscopic examination revealed a sheathed microfilaria exhibiting characteristic features of W. Bancrofti , including a slender body with smooth curves, a distinct she ath, and a nuclei-free tail tip (Figure 1, 2a,2b)) The patient subsequently underwent vaginal hysterectomy with bilateral salpingo-oophorectomy. Histopathological examination (Figure 3a,3b) showed chronic cervicitis, secretory endometrium, right ovarian serous cystadenoma, and bilateral hydrosalpinx. (Figure 3) No evidence of atypia, malignancy, adult filarial worms, or tissue infiltration by microfilariae was identified.

and Review of Literature Lymphatic filariasis continues to be a significant public health concern in many tropical and subtropical countries, including India, where W. Bancrofti is responsible for the majority of cases. Although microfilariae are commonly detected in peripheral blood and lymphatic channels, their presence in cervicovaginal cytology smears is extremely uncommon. (5) Since the female genital tract is not a usual site of filarial infestation, identification of microfilariae in Pap smears is generally unexpected and often represents an incidental finding. The occurrence of microfilariae in cervicovaginal smears was first documented by Walter et al ., [6] following which only sporadic case reports and small case series have appeared in the literature. Most patients reported in these studies were clinically asymptomatic for filariasis and presented with nonspecific gynecological complaints such as vaginal discharge, abnormal uterine bleeding, pelvic pain, or postmenopausal bleeding. In the present case, the patient presented with abnormal uterine bleeding and had no clinical features suggestive of lymphatic filariasis, making the cytological finding particularly unexpected. A recent study by Kumar et al . [7] from Bihar described four cases of incidental detection of W. Bancrofti in routine cervicovaginal Pap smears. Similar to our patient, the majority of these women had no clinical suspicion of filarial infection, and the diagnosis was established solely through cytological examination. Such reports (Table1) highlight the important role of routine cervical cytology in identifying occult filariasis, especially in endemic regions where the disease burden remains high. Summary of previously reported cases of microfil ariae detected in cervicovaginal cytology (Table 1) Table 1: Summary of Previously Reported Cases of Microfilariae Detected in Cervicovaginal Cytology Author Year Presentation Cytology Type Associated Lesion Walter et al. (6) 1983 Vaginal bleeding Conventional smear None Dhanya et al. (11) 2016 Vaginal discharge Pap smear None Singla et al. (4) 2020 Routine screening Pap smear None Kumar et al. (7) 2022 Asymptomatic cases Pap smear None Present case 2026 Abnormal Uterine Bleeding LBC Serous cystadenoma + bilateral hydrosalpinx The mechanism by which microfilariae reach the cervicovaginal region is not completely understood. Several theories have been proposed, including lymphatic obstruction, rupture of lymphatic vessels, inflammatory damage to vascular structures, and increased vascular permeability, all of which may facilitate migration of microfilariae into surrounding tissues and exfoliated cellular material [5, 8]. In our patient, the presence of chronic cervicitis and local inflammatory changes may have contributed to the pa ssage of microfilariae into the cervicovaginal smear. The increasing use of Liquid -Based Cytology (LBC) has improved the quality of cervical screening by providing cleaner backgrounds and better cellular preservation [9]. Although the processing technique may cause minor morphological alterations in parasites, characteristic features of W. Bancrofti, including the delicate sheath, smooth curves of the body, and nuclei -free tail tip, are usually well preserved. These features enabled accurate identification of the organism in our case despite the absence of detectable microfilaremia in the peripheral blood smear [10, 11]. Such findings emphasize that a negative peripheral smear does not exclude occult filarial infection. An additional noteworthy feature of this case is its association with a right ovarian serous cystadenoma and bilateral hydrosalpinx. While microfilariae have occasionally been reported in association with both benign and malignant lesions of the female genital tract, coexistence with serous cysta denoma and bilateral hydrosalpinx is exceptionally rare. Histopathological examination of the surgical specimen did not reveal adult worms or tissue infiltration by filarial organisms, suggesting that the microfilariae represented an incidental occult infection rather than a direct cause of the adnexal pathology. The present case underscores the importance of careful and systematic evaluation of all cytological smears, including those reported as negative for intraepithelial lesion or malignancy (NILM). In regions where filariasis is endemic, awareness of such unusual presentations is essential, as incidental cytological detection may provide the first clue to an otherwise clinically silent infection. Early recognition facilitates timely treatment and may he lp prevent the long -term complications associated with chronic lymphatic filariasis.

Incidental detection of W. Bancrofti microfilariae in Liquid - Based Cytology smears is an uncommon but important finding. The coexistence of microfilariae with ovarian serous International Journal of Clinical Obstetrics and Gynaecology https://www.gynaecologyjournal.com ~ 2527 ~ cystadenoma and bilateral hydrosalpinx makes the present case particularly noteworthy. This report highlights the valu e of meticulous cytological examination in routine cervical screening and reinforces the need for vigilance among cytopathologists working in filariasis -endemic regions. Even in smears reported as NILM, careful screening may reveal unexpected findings that have significant diagnostic and clinical implications. Fig 1: 40X, PAP Stain, Microfilariae-Sheathed organism, enlongated body with tapering tail Fig 2a, b: 100X, PAP SMEAR, Microfilariae-body composed of a dense column of tightly packed nuclei. Fig 3a, b: 40X, Right Ovary, HPE, Cyst lined by flattened to cuboidal epithelium-Serous Cystadenoma International Journal of Clinical Obstetrics and Gynaecology https://www.gynaecologyjournal.com ~ 2528 ~ Conflict of Interest Not available Financial Support Not available

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