Giant, primary, hydatid cyst of the gluteal region

Background: Primary hydatid disease in the muscle is extremely rare, resulting in either the spread of cysts spontaneously or after operations for hydatidosis in distant regions. Methods: Report of an unusual case of primary hydatid cyst in the gluteus muscle, behaving as enlarging soft-tissue tumour, with a review of the literature. Results: Magnetic resonance imaging revealed an intramuscular cyst in the gluteus muscle; and no cyst existed in any other location. The cyst was excised totally, and the diagnosis of muscular cystic hydatidosis was confirmed by histopathologic examination. In follow-up of two years after the operation, there has been no recurrence in either patient. Conclusion: The involvement of the gluteus maximus muscle without the evidence of hepatic or pulmonary disease is rare, characterized by slow development, but a major local extension must be considered in the differential diagnosis of a cystic mass with well-defined margins in the extremities of individuals from endemic regions. Physical examination, serology results and radiological findings should be interpreted with care, especially in hydatid cyst endemic countries. Surgery is still the treatment of choice, with total cyst excision.