[Retrovesicular hydatidosis in childhood. Possibilities of differential diagnosis]

We present a case of retrovesical hydatid cyst in a boy coincident with a right kidney malrotation which complicated, in view of the negative results of the specific tests for hydatidosis, the possibilities of a differential diagnosis, and although the correct etiology was suspected before the operation, only the histopathological study of the specimen confirmed the initial suspicion. The differential diagnosis was posed with the retroperitoneal cystic tumours such as the teratoma and basically with the deep pelvic cysts in the male (mullerian cysts, seminal vesicle cysts and cysts of Wolff's duct).