Hydatid Cyst, Solitary Primitive with Atypical and Unusual Muscular Localization: Report of 02 Cases

Introduction: Hydatidosis is a cosmopolitan parasitic infection caused by the larval stage of Echinococcus granulosus. While the liver and lungs are the most affected organs, involvement of other sites is less frequent. Hydatidosis developing within the subcutaneous or muscular tissue is an exceedingly rare occurrence. Materials and Methods: Case 1: A 56-year-old female presented with a left basithoracic tumor infiltrating between the internal and external oblique muscles on MRI. Hydatid serology were negative, but the diagnosis of muscular hydatidosis was strongly suspected based on clinical and radiological evidence. The patient underwent total pericystectomy, with no recurrence at one-year follow-up. Case 2: A 85-year-old female was referred to our hospital for an asymptomatic soft tissue tumor located in the root of the right thigh, progressing for 3 years and measuring 11cm. Ultrasound and MRI, revealed an encapsulated lesion exhibiting both cystic and tissue components with multiple compartments. The patient underwent complete surgical excision, and histopathological-exam confirmed the diagnosis. No postoperative medical treatment was administered, and there was no recurrence after a 4-year follow-up. Discussion: The frequency of muscular hydatid cysts varies from 1 to 5.4% of all hydatid locations. Muscular hydatid cysts pose challenges in detection through serological tests, but a positive result provides diagnostic certainty. Ultrasound is the imaging modality of choice, MRI is recommended for cases where uncertainty persists and for local-regional evaluation. The primary treatment for muscular hydatidosis is surgical. The use of medical treatment with Albendazole remains highly controversial. Long-term patient follow-up is crucial to detect any local or distant recurrence. Conclusion: In the presence of any subcutaneous or muscular mass in a patient residing or having resided in an endemic area, the diagnosis of muscular hydatid cyst should be considered,