Don’t miss it: Extremity-located cyst hydatid may mimic soft tissue tumors

OBJECTIVES: In this study, we present our experience in patients with hydatid cysts located intramuscularly. PATIENTS AND METHODS: Between May 2018 and May 2023, a total of 11 patients (3 males, 8 females; mean age: 29.1±13.6 years; range, 8 to 56 years) with intramuscular hydatid cysts were retrospectively analyzed. Demographic data, laboratory values, serological test results, location and size of the cyst, radiological imaging findings, and complications were recorded. RESULTS: The mean follow-up was 44.3±17.3 (range, 5 to 60) months. The mean mass size at the time of admission was 5.4±3.3 (range, 2 to 14) cm. Serologic tests were positive in the majority of cases (72.7%). Eosinophilia was negative in 72.7% patients. The rate of isolated muscle involvement was 81.8%. The rate of lower extremity involvement was 72.7%. The most common involvement was leg (36.4%), thigh (18.2%), and shoulder (18.2%). One patient developed compartment syndrome after cyst rupture during neoadjuvant antihelmintic therapy. There was no recurrence in any of the patients. CONCLUSION: Hydatid cysts should be considered in the differential diagnosis of slowly growing, deeply located, painless soft tissue masses, particularly in endemic areas. Although it is a rare complication, compartment syndrome may develop after spontaneous cyst rupture. Neoadjuvant antihelmintic chemotherapy can reduce complications. The combination of total surgical excision and chemotherapy yields successful results in the treatment of hydatid cysts located in the muscle.