Hydatid Cyst of the Thigh: A Report of a Rare Case With Literature Review.

Hydatid cyst (HC) is a parasitic infection originating from the cestode of the Taeniidae family, predominantly occurring in the liver and lungs. Muscular involvement, however, remains a rarity. This report delineates the case of a 32-year-old female from Saudi Arabia presenting with a six-month history of an enlarging mass in her left thigh accompanied by significant localized pain. The clinical features were suggestive of an abscess, yet diagnostic imaging, specifically ultrasound, uncovered the presence of multiple daughter cysts within a primary lesion. MRI confirmed a well-defined encapsulated cystic mass. With an additional backdrop of a previously treated hepatic HC and living in proximity to a domestic cat, the clinical suspicion gravitated toward echinococcosis. Following surgical excision of the cystic lesion, histopathological examination confirmed the diagnosis of an infected HC. Postoperatively, the patient displayed an uneventful recovery with no recurrence or complications. This case underscores the diagnostic challenge posed by HC, especially in non-typical locations, and the pivotal role of imaging modalities in facilitating accurate diagnosis and subsequent management.