Cystic echinococcosis in Austria 2009–2024: national surveillance and two rare cases of musculoskeletal manifestations including clinical management strategies

BACKGROUND: Cystic echinococcosis (CE), caused by Echinococcus granulosus, is a parasitic disease that predominantly involves the liver and the lungs, whereas primary involvement of the musculoskeletal system is rare and diagnostically challenging. This study examines isolated musculoskeletal echinococcosis (MSKE) through two uncommon cases treated at an Austrian tertiary centre and proposes a tailored diagnostic and therapeutic approach. To contextualise their rarity, national epidemiological data on CE in Austria over a 15-year period are also presented. METHODS: We queried our institutional database for cases of MSKE managed at an Austrian tertiary orthopaedic centre (2002-2024) and present these as case reports. In addition, we analysed all nationally reported cases of CE in Austria (2009-2024) using data from the electronic epidemiological reporting system. RESULTS: Two patients with MSKE were treated at our centre. A 34-year-old Syrian woman presented with a slowly enlarging thigh mass, while a 53-year-old Turkish woman developed recurrent bilateral sacroiliac joint involvement 16 years following surgical resection of a primary hydatid cyst. In both cases, disease was confined to the musculoskeletal system. A total of 323 CE cases from all anatomical sites were included (median age 38 years, IQR 27-52; 50.8% male). Among cases with known infection origin, 53.6% were imported, and among those with available sample data, 81.2% were diagnosed via serum. The annual case count peaked in 2017 (n = 40) and was lowest in 2009, 2012, and 2015 (n = 4 each). A significant temporal trend was observed over 2009-2024 (p = 0.006). CONCLUSION: Hydatid cysts should be considered in the differential diagnosis of patients presenting with slow-growing musculoskeletal masses, particularly when initial imaging and clinical history suggest a parasitic aetiology. When localised, complete surgical excision with removal of the intact cyst is curative. Systemic anthelmintic treatment is administered perioperatively or as a conservative option in patients who are not suitable candidates for surgery.