Hydatidosis is an anthropozoonosis caused by the larval stage of Echinococcus tapeworms. 1 It is a worldwide infectious disease but highly endemic in North Africa, the Middle East, and South America. 2 It could be caused by different species, but Echinococcus granulosus species is responsible for more than 95% of human hydatid disease. 3 The latter is mainly encountered in pastoral areas where the contact between dogs and sheep is frequent. The prevalence of this disease is most likely underestimated due to its asymptomatic character. 3 This parasitic disease most commonly affects the liver and the lung; however, it seldom concerns the bone and the soft tissues. In fact, the musculoskeletal involvement in hydatid disease is only reported in 0.5 to 2% of all cases and it is usually secondary to visceral involvement. 1,4 Although it is an old disease, the diagnostic of hydatid bone is still challenging given the delayed clinical manifestations and the nonspecific radiological features. 5 We herein report a case of a primary bone hydatid disease of hip, pelvis, and the surrounding soft tissues. | CASE REPORTA 49-year-old man was admitted to our hospital with oneyear history of a progressive left hip pain that is restricting his daily activities. The patient was living in an urban

Background:Osseous hydatid cyst is an uncommon disease with weak response to treatment.hydatid disease should be included in the differential diagnosis of cystic lesions of bone in endemic regions. Bone cysts account for only 0.5 to 2.5% of all hydatid cysts in humans.Objectives:To report a case of osseous hydatid disease extended on hip and femurMethods:We report a case of osseous hydatid diseaseResults:A 49 YEAR OLD BRICKLAYER, with no past-medical history and no animal contact, was admitted to our department for a left hip pain. the patient was apyretic and in a good general health condition. He had a very painful walk. the mobilility of the left hip joint was very painful and restricted.The pelvis X-rays showed osteolytic lesions in the ischiopubic branch and in the left femur and proximal extremity of the tibia.The C-Reactive protein value, the protein electrophoresis were normal. tumor markers test was negative.An ultrasound of the hip showed a low abondance intra-articular effusion. The Pelvic MRI showed multilocular appearance extending over the bone and muscle with breach of the bone cortex of the femur very suggesting of the diagnosis of a bony and muscular echinococcosis.NO other localization of hydatidosis were detected, body ct scan was normalConclusion:Hydatid disease occurs worldwide and mainly associated with sheep farming. The liver and lungs are the most common locations. Bone cysts are uncommon but severe. Although immunofluorescent assays are useful, the final diagnosis depends on histology. The treatment is almost surgery. Recurrence is commonDisclosure of Interests:None declared