Hydatid disease is more frequent in the sheep raising communities of Middle East, Central Europe, Australia, India, Turkey and South America.[
2] Echinococcosis of the urogenital tract is a rare condition, and the kidney is the most frequently affected organ (2–4%). Seminal vesicle involvement is very uncommon and only a few cases have been reported in the literature.[
3–
6] In most of these patients, coexistent echinococcal cysts were found in other sites, especially in the liver. Isolated pelvic and retroperitoneal hydatid cysts are exceedingly rare and a pathogenic origin via haematogenous or lymphatic routes has been proposed for cases in which primary visceral lesions are absent.[
5,
7] Such cysts generally remain asymptomatic until their space occupying effect on adjacent organs elicits symptoms. Therefore, a pelvic hydatid cyst may present with voiding dysfunction, urinary retention, hemospermia and azoospermia. Accidental detection is not infrequent.[
2–
4,
6]
In the initial stages, the hydatid cyst is usually unilocular. As the cyst matures, it transforms itself into a larger multivesicular and occasionally multilocular cyst containing numerous daughter cysts. The walls of the cyst are usually thin, smooth and well defined with thin fluid within the cyst. The parasite dies once the nourishing fluid inside the cyst is exhausted followed by partial or complete calcification of the cyst wall. The most feared complication of echinococcosis is rupture of the cyst with anaphylactic allergic reaction in addition to causing the spread of the disease.[
5,
6]
Routine laboratory tests can only reveal eosinophilia. A number of serological tests can be done for screening, diagnosis and follow up for recurrence of hydatid disease. Highly sensitive tests include indirect haemagglutination and Latex agglutination test. Confirmation of diagnosis can be done by highly specific tests including immunoelectrophoresis, double diffusion test, enzyme-linked immunosorbent assay (ELISA) and radioallergosorbant test.[
1,
7] In our patient ELISA for hydatid disease was negative. Imaging studies play a decisive role in the diagnosis of pelvic echinococcosis, especially Ultrasonography (USG) (abdominal and transrectal), computed tomography (CT) and MRI. Echinococcal cysts may appear thick-walled with multiple septations. Daughter cysts are often recognized inside a large mother cyst (cyst within the cyst appearance), as well as a fluid level due to the existence of ‘hydatid sand’.[
3,
5,
6] We performed abdominal USG, trans-rectal ultrasonography and MRI in our patient which revealed a pelvic hydatid cyst in relation to the right seminal vesicle.
The differential diagnosis of pelvic echinococcosis may turn out quite challenging and should include congenital or acquired cyst of the seminal vesicles (parasitic, infectious or obstructive), cystic adenoma of the seminal vesicles, Mullerian duct cyst, cyst or diverticule of the vas deferens/ejaculatory duct, prostatic retention cyst, as well as primary retroperitoneal sarcoma, teratoma and leiomyoma.[
3]
Surgery remains the treatment of choice for hydatid cyst.[
1–
7] Antihelminthic chemotherapy alone may be effective in 30-40% of patients. It is most effective in alveolar hydatid, less so for liver infections and essentially ineffective for the diseases of the bone, brain, eye and other sites.[
1] Hydatid cyst is best treated by complete excision of the cyst with extreme caution to avoid accidental puncture and parasite spillage. We treated our patient with total cystectomy (cystopericystectomy) with preservation of the seminal vesicle. Prophylactic albendazole was also used.
Late complications which should be kept in mind are the local recurrence of the disease and development of hydatidosis at the primary sites. The patient has to be kept on regular follow up paying attention to these possibilities.[
7]
