[Hydatid cyst of the psoas muscle].

While hydatid cysts may occur in any area of the body, isolated muscular localizations are rare. Only some thirty-odd such cases have been reported. The authors report the case of a 38-year-old man who consulted for isolated abdominal pain in the left iliac region. Radiographic study showed a simple hydatid cyst of the left psoas muscle. The cyst was removed by extraperitoneal transverse laparotomy. Crural nerve palsy occurred but regressed after 2 months and had not recurred after 24 months. Ultrasonography is the preferred method for detecting muscular hydatid cysts. No other diagnostic tool is needed. Surgical treatment remains best. We recommend the unroofing technique over pericystectomy. Other cyst localizations must be sought before any therapeutic decision, since they determine the initial surgical management and allow consideration of other therapeutic methods to be combined with surgery.