[Isolated retroperitoneal hydatid cyst. Apropos of 4 cases].

The isolated retroperitoneal cyst is rare. The hydatid cyst grow behind the posterior parietal peritoneum and have no connection with organs normally located within that space and lying next to them. Out of the 31 retroperitoneal tumors files collected over a five-year period, 25 are authentic primitive retroperitoneal tumors and 6 retroperitoneal hydatid cysts; 4 of which are isolated retroperitoneal localisations (neither pelvic subperitoneal localisation, nor multiple hydatic localisation are covered in this work). The abdominal mass is the most frequent sign, unfrequently concomitant with compressive syndrome. Diagnosis is based on urographic and echographic data. These data enabled a diagnosis to be reached in two cases and helped the diagnosis in one case. Surgery is the only treatment.