Primary Hydatid Cysts in the Extremities: A Systematic Review of the Literature.

Primary hydatid cysts (PHCs) in the extremities are uncommon, presenting in the majority of cases with atypical clinical features. Radical surgical excision remains the mainstay of treatment. The aim of our study was to accumulate the already published data on PHCs in the extremities in terms of demographic, diagnostic, and therapeutic aspects. Three electronic databases were meticulously searched for articles published until 2024. A total of 85 studies comprising 118 patients were finally included in our review. Sixteen patients (13.5%) were diagnosed with a hydatid cyst in their upper extremity, 94 (79.7%) with a PHC in the lower extremity, and eight (6.8%) with an echinococcal cyst in the axilla. Pain and swelling were the most frequent symptoms, whereas only two patients were completely asymptomatic. The mean lesion size was 11.6 ± 7.1 cm. Preoperative serology investigation was reported in 82 out of 118 (69.5%) patients; among them, 33 (44.6%) cases had a positive preoperative serology test. The vast majority of patients (96.6%) were treated with an interventional procedure either surgical or radiological, and only seven experienced postoperative complications. No anaphylactic reaction was described perioperatively. Although preoperative diagnosis of PHCs is challenging, they should be considered in the differential diagnosis of soft tissue lesions. Treatment strategies should be individualized on a patient basis, while radical surgical excision remains the gold standard treatment.