A primary ovarian hydatid cyst: uncommon site of echinococcosis (case report)

¹University of Tunis El Manar, Faculty of Medicine of Tunis, 1007, Tunis, Tunisia, ²Department A of Gynecology and Obstetrics, Charles Nicolle University Hospital of Tunis, 1006, Tunis, Tunisia, ³University of Sousse, Faculty of Medicine of Sousse, 4000, Sousse, Tunisia, ⁴Regional Hospital of Kasserine, Department of Gynecology and Obstetrics, 1200, Kasserine, Tunisia, ⁵Charles Nicolle University Hospital, Department of Radiology, 1006, Tunis, Tunisia, ⁶Department of Anatomic Pathology, Charles Nicolle Hospital, Tunis, Tunisia

^&Corresponding author
Ghada Abdelmoula, Department A of Gynecology and Obstetrics, Charles Nicolle University Hospital of Tunis, 1006, Tunis, Tunisia

Introduction    

Hydatid disease is a zoonotic infection caused by Echinococcus granulosus or rarely by Echinococcus multilocularis. This infection is endemic in underdeveloped countries and continues to be a significant health issue in areas where animals are still being raised without veterinary control, the especially Mediterranean region, the Middle East, Africa, and some countries of South America [1]. Although the liver and lungs are the most affected organs, constituting 90% of all hydatid cysts [2], the disease can be seen anywhere in the body. Pelvic localizations are rare and represent less than 1% of all localizations [3]. Unusual localizations of this disease can be the source of diagnostic difficulty. In addition to that, radiologic findings are non-specific in many cases and may point to another diagnosis, especially in unusual sites and in the absence of other hepatic or pulmonary localizations. We are presenting the case of an unusual presentation of an isolated ovarian hydatid cyst diagnosed on the occasion of pelvic pain and considered an ovarian tumor.

Patient and observation     

Patient information: a 62-year-old woman menopausal for 5 years, G5P5 (5 living children), without any past medical history, under contraception by intrauterine device (IUD) not removed for 8 years, was referred to our consultation for pelvic pain and post-menopausal metrorrhagia.

Clinical findings: physical examination revealed pelvic tenderness without any other abnormal findings.

Diagnostic assessment and timeline of the current episode: pelvic ultrasound revealed a mixt pelvic mass (solid and cystic components), with no obvious vascularity on color Doppler (Figure 1). An MRI showed a multiloculated cystic mass of the left ovary without any calcification, associated with a small pelvic effusion. There was no adenomegaly or liver injury (Figure 2). Laboratory results did not show any abnormality. Tumor markers were negative.

Therapeutic interventions: a laparotomy was decided, and an excision of the whole ovary including the cyst with the fallopian tube was done. An accidental rupture of the cyst occurred during surgery, revealing daughter vesicles (Figure 3, Figure 4). The specimen was addressed to the pathology laboratory.

Follow-up and outcome of interventions: examination of the cyst showed a fluid containing scolices and hooklets on direct examination. Hematoxylin and eosin-stained sections showed the pericyst, laminated hyaline ectocyst, and the endocyst or inner germinal layer (Figure 5). After surgery, the patient was treated with Albendazole, and she had no signs of recurrence or dissemination during two years of follow-up.

Diagnosis: a primary ovarian hydatid cyst was confirmed.

Patient perspective: during her hospitalization, the patient was satisfied with the care she received and seemed optimistic about the evolution of her state of health.

Informed consent: the patient gave informed consent.

Discussion     

Pelvic hydatid localization is an uncommon site of hydatid disease, with an incidence varying between 0.5-2.5% [4] with the ovary being the leading site of involvement in such cases [5]. Commonly, pelvic cysts are due to the dissemination of another site, either spontaneously or after rupture or surgery of the primary disease [6]. In our case, ovarian hydatidosis was primary since none of the other organs were involved. Clinically, the presentation of ovarian hydatid cysts is usually non-specific and can include pelvic pain, menstruation irregularities, urinary disturbance, or simply pelvic heaviness [7]. The diagnostic difficulty of this pathology lies in the non-specificity of its clinical symptomatology and the variability of its imaging appearance [8].

In fact, ovarian echinococcosis can mimic either polycystic ovarian disease or ovarian malignancy [6]. In imaging, hydatid disease can have the appearance of a multiloculated cyst due to the presence of multiple daughter vesicles, as reported in our case, or be in the form of a solid ovarian mass. Ultrasound is an important imaging tool that can reveal the characteristic appearance of a «fluctuating membrane», or «honeycomb aspect» of the daughter cysts, strongly suggestive of a hydatid disease. Computed tomography (CT) scan adds the demonstration of wall calcifications. Magnetic resonance imaging is not obligatory if the diagnosis was already confirmed by other imaging modalities and serology. It´s performed if a malignant origin is suspected. A hydatid cyst appears like a cystic lesion that can be unilocular or multilocular. Daughter cysts may appear slightly hypointense or isointense to the maternal matrix on T1-weighted images and always hyperintense on T2-weighted images. Floating membranes when present are seen as low signal-intensity linear structures on both T1 and T2-weighted sequences [9].

In front of a similar aspect, the possibility of a hydatid cyst must be evoked especially in patients coming from endemic areas, in order to take the necessary precautions during surgery, to reduce the risk of cystic rupture, which can lead to anaphylaxis or dissemination. Hydatid serology is of great help to orientate the diagnosis, especially in the absence of other hydatid localizations, but its sensitivity varies from 67% to 87% [5]. Surgery is the only curative treatment for hydatid disease. Ovarian cystectomy when possible is the gold standard treatment [10]. Medical treatment (Albendazole) can be administered pre-operatively to sterilize the cyst or in post-surgery as was prescribed in our case to reduce the risk of dissemination. Less radical surgical measures such as PAIR (puncture, aspiration, injection, and re-aspiration) were performed in some cases where radical surgery was not possible.

Conclusion     

Ovarian hydatidosis is a rare disease. It can be primary or more frequently secondary to other sites. Although the radiological aspect is non-specific, it can be strongly suggestive. Hydatid serology is of great help when it is positive. Surgery is the only radical treatment with chemotherapy to avoid recurrence. Prior recognition of the possible hydatid nature is preferable in order to minimize the risk of cyst rupture. Ovarian echinococcosis should be kept in mind such as a differential diagnosis with ovarian cysts and malignancies in patients coming from endemic areas or with a history of hydatid surgery.

Competing interests     

The authors declare no competing interests.

Authors' contributions     

Mariem Garci and Saoussam Armi ensured conceptualization and methodology. Fatma Dhieb was responsible for data curation and the writing of the original draft preparation. Ghada Abdelmoula was responsible for writing- reviewing and editing. Mehdi Makni and Linda Hadj Kacem ensured visualization and investigation. Nabil Mathlouthi, Olfa Slimani and Cyrine Belghith administered and supervised this project. All the authors have read and agreed to the final manuscript.

Figures     

Figure 1: A,B) ultrasound images showing a left latero-uterine mass, multiloculated, with thick membranes

Figure 2: A) coronal T2-weighted MRI image showing a multilocular cyst of the left ovary, with thick peripheral hypointense membrane (red arrow), and detached internal membranes; B) axial post-gadolinium fat-suppressed T1 weighted image showing enhancement of the vascularized part of pericyst (white arrow)

Figure 3: intraoperative findings showing the pericyst adherent to the ovarian tissue and myometrium, with thick white membranes

Figure 4: the operative piece shows the peripheral membrane with daughter cysts

Figure 5: microscopic examination shows a thick fibrous pericyst adherent to the myometrium (magnification x 20)

References