A rare case of hydatid disease of the testis

Clinical History

A painless mass was found in both testes. CT scanning revealed a round mass of low density in the right testis with a peripheral rim of calcification.

Imaging Findings

A Greek patient was admitted with swelling of both testes, which had been growing slowly over the previous ten months. He had not experienced any pain and had no previous history of any kind.

Physical examination showed a painless mass in both testes. The inguinal lymph nodes were normal and there were no other pathological findings. The chest X-ray, excretory urogram and urinalysis were all normal. On the blood count, eosinophilia (19%) was the only abnormal finding.

An ultrasound (US) examination of the scrotum was the next imaging procedure. It demonstrated bilateral hydroceles. The scrotal sac was thickened. In the right scrotal sac a hypoechoic mass with a rim of calcification was present with a characteristic acoustic shadow. The testes had a relatively homogenous texture. The volume of both testes was reduced. Inflammation of the genital tract was suspected.

Further evaluation was performed with computerised tomography (CT) of the lower abdomen and scrotum. This revealed a round mass of low density in the right testis with a peripheral rim of calcification. Also a similar mass was identified in the left pelvic floor. An additional scan of the whole abdomen and thorax showed two similar masses in the liver. No other findings were demonstrated.

The most propable diagnosis was hydatid disease. A right high inguinal orchiectomy was performed and a final diagnosis of hydatid disease was established. Further treatment was administred with the anti-echinococcal drug albendazole. Two years after the operation, follow-up studies did not show any new findings of hydatid disease elsewhere in the body.

Discussion

Hydatid disease is prevalent through much of the world. In man there are two main forms, due to Echinococcus granulosus and less frequently to Echinococcus multilocularis. The dog or other carnivore is the definitive host and the sheep or other ruminant is the intermediate host. Man becomes infected by contact with a definite host or by consuming contaminated water or vegetables. Hydatid disease has been reported in all parts of the human body, most commonly in the liver, lungs and abdominal cavity. Hydatid disease may also be found in the kidney, pancreas, brain, bone, spine and heart. Rare locations are the retroperitoneum, salivary glands and thyroid. Cysts are multiple in up to 60% of cases. Most cysts are acquired in childhood and are not diagnosed until the third or fourth decade. Hydatid disease, although known to occur in most organs and body areas, is extremely rare in the genital system. To date only a very few cases have been reported in the testis. Hydatid cysts in the testis show the same features as hydatid cysts in other parts of the human body. The hallmark of hydatid disease, the ring or curvilinear calcification, may be present.

Both US and CT can imply the diagnosis or can exclude hydatid disease.

Differential diagnosis should include thickening of the tunica layers as a result of chronic epididymo-orchitis and chronic peri-orchitis. If inflammation has been severe or persistent over a long period, plaques of calcification may form on the surface of tunica layers. Also the testis may be atrophic. Atrophy may result from a wide range of causes including chronic inflammation, ischaemia and trauma. Many conditions are encountered in scrotal swelling. Scrotal calculi are a well-recognised phenomenon and they are frequently mobile. Small calcifications may be seen in the testis, as a result of previous testicular inflammation, often in association with testicular atrophy and even in malignant tumours, like teratomas and embryonal cell tumours. Benign cysts of the testis, such as cystic dysplasia, are uncommon. The cysts may be related to previous trauma, sometimes with some associated calcification, the rete testis or the inner layer of the tunica albuginea. Some testicular neoplasms are predominantly cystic, like cystic teratoma and cystadenocarcinoma. The differentiation is subtle and potentially dangerous, because most testicular tumours are malignant.

Hydatid disease always should be considered in the differential diagnosis of testicular masses, especially in endemic areas and if the patient has hydatid cysts elsewhere in the body.

Differential Diagnosis List

Final Diagnosis

Hydatid disease of the testis

URL:	https://www.eurorad.org/case/1700
DOI:	10.1594/EURORAD/CASE.1700
ISSN:	1563-4086