Yilmaz, MehmetPirimoglu, Rüstem BerhanGuzel, IsmailAYERDEN, DilaUcmak, Hacer2025-10-242025-10-2420251301-56802149-8156https://doi.org/10.5606/tgkdc.dergisi.2025.27358https://search.trdizin.gov.tr/tr/yayin/detay/1334074https://hdl.handle.net/20.500.12899/2786This case report presents a rare occurrence of both subcutaneous and cardiac hydatid cysts in a pediatric patient. A 10-year-old girl admitted with a rapidly enlarging, painful mass in the right dorsal scapular region. During a biopsy procedure under sedation, the patient developed an anaphylactic reaction and subsequent cardiopulmonary arrest. After successful resuscitation, cardiac echocardiography revealed a large hydatid cyst in the interventricular septum. In conclusion, potential complications should always be considered during invasive procedures. In addition, in patients with musculoskeletal masses, a whole-body magnetic resonance imaging may detect and prevent potential complications at an early stage.eninfo:eu-repo/semantics/openAccessAnaphylaxishydatid cystcardiac hydatid diseasesubcutaneous cyst.Article10.5606/tgkdc.dergisi.2025.273583311091121334074