[Hydatid cyst on horseshoe kidney].

Hydatid cyst on horseshoe kidney is a rare entity in temperate climates and the diagnosis is often delayed. The clinical features are marked by signs of compression of adjacent organs, mass syndrome and pain. The diagnosis is based on ultrasonography and CT. Arteriography can be useful to study the blood supply of the horseshoe kidney. Treatment is surgical and must remain conservative, as this is a benign disease. In a small percentage of cases, the hydatid cyst can be mistaken for a cystic malignant renal tumour, but the diagnosis is confirmed by serology. The course is usually favourable.