A rare primary hydatid cyst of the psoas muscle in a rural setting: A case presentation

Hydatid cyst is a zoonosis caused mainly by the larval stage of the cestode worm Echinococcus granulosus, hydatidosis is frequently found in sheep-raising countries such as the Mediterranean countries. The disease usually involves the liver (75%) and lung (15%). We describe a case of hydatid cyst of the psoas muscle; we are reporting this case because of its rarity and its difficulty to diagnose clinically. A 16 –year-old female from rural setting, presented to the department of surgery of our institution, with complaints of right flank pain. On abdominal examination, there was sensitization in the right lower quadrant, and there was no resistance or rebound. On abdominal ultrasonography, a 6 × 6 cm hydatid cyst was detected within the psoas muscle, which was confirmed by positive indirect hemagglutination, no other organ involvement has been detected by CT scan. A pericystectomy was performed; the intact intramuscular cyst was completely excised, Macroscopic and microscopic examination of the specimen confirmed Hydatid cyst. The patient was discharged from hospital on the fifth postoperative day. No local recurrence was detected during postoperative follow up. Hydatidosis should be considered in cases of a symptomatic swelling in musculoskeletal system without history of trauma and irradiation when patients belong to endemic area. Cyst or complex retroperitoneal tumors, cold or pyogenic abscess of psoas muscle are considered in differential diagnosis. In the light of this case and the literature data, we discuss the diagnosis and the therapeutic problems raised by hydatid cyst of the psoas muscle. •Hydatid cyst is a parasitic common disease in sheep breeding areas, especially in Mediterranean countries.•Hydatid cyst of the psoas muscle is important to know because of its rarity and its difficulty to diagnose clinically, especially in young people.•Hydatid cyst should be considered in the presence of any painless cyst mass of muscle in endemic regions. Unilateral and primitive forms are mainly reported.•Excision of the intact intramuscular cyst completely is required to avoid contamination and recurrence.•Cyst or complex retroperitoneal tumors, cold or pyogenic abscess of psoas muscle are considered in differential diagnosis.