Primary Suppurative Hydatid Cyst of the Thigh in a Child: A Case Report

Abstract

Background: Primary muscular hydatid disease is an extremely rare clinical entity, accounting for less than 3% of all echinococcosis cases. Its presentation often mimics other soft tissue tumours or infections, creating diagnostic challenges. Aim: This report describes an unusual case of a primary suppurated hydatid cyst located in the thigh of a paediatric patient. Presentation of Case: A 5-year-old boy with a history of close contact with dogs presented with a painful inflammatory swelling on the posterior aspect of his right thigh that had persisted for six months. Clinical examination revealed a fever of 38.9°C and homolateral inguinal lymphadenopathy. Laboratory investigations revealed hyperleucocytosis, hypereosinophilia, and elevated inflammatory markers; however, hydatid serology was negative. Ultrasonography revealed a thick-walled cystic lesion with mobile echogenic content. Magnetic resonance imaging (MRI) confirmed the diagnosis of a suppurated hydatid cyst arising from the gluteus maximus muscle. Five days after targeted intravenous antibiotic therapy, complete surgical resection of the cyst was performed. Postoperative recovery was uneventful, and no recurrence was observed during the 24-month follow-up period. Discussion and Conclusion: Hydatid cysts should be considered in the differential diagnosis of soft tissue masses in the extremities, particularly in endemic regions or in patients with relevant exposure, even when serology is negative. Advanced imaging, specifically MRI, remains the gold standard for identifying pathognomonic signs and planning surgical excision to prevent complications and recurrence.