Primary Hydatid Cyst of the Thigh , an unusual localization: a case report

Introduction: subcutaneous musculoskeletal hydatid cysts are rare ,representing around 1-5%.it mimics a soft tissue tumor ,so preoperative radiological diagnosis is important to choose the treatment. case presentation: this case was presented to clinic in prince ali hospital in karak . a 78 years old female patient was presented complaining of right medial thigh swelling which appeared a few weeks ago.the swelling caused discomfort and pain .on exam ,a lump was located in the medial aspect of the right thigh,round,soft,non mobile. her us revealed multiple well defined cystic lesions in the posterior aspect of the thigh, with internal septae mostly representing a hydatid cyst. a mri was ordered and showed a large,multi-lobular, thin walled and non-calcified fluid containing cyst. the appearance was consistent with a hydatid cyst.next,the patient underwent abrain,chest and abdominal ct to check if there was aprimary source,the results were negative.an echinococcus granulosa titer test was ordered, the result was negative. treatment options were discussed.we preferred to start with the conservative approach.so,a high dose of albendazole was started,with regular follow up in the clinic,but conservative treatment failed so we decided to continue with surgical treatment by complete excision. conclusion: echinococcal disease should be considered in any patient who presents with a cystic mass despite body location. especially in endemic areas.