The deceptive cysts of echinococcus granulosus in the thigh: A case series and review of diagnostic and management challenges.

INTRODUCTION: Hydatid cyst disease, caused by the larval stage of Echinococcus granulosus, is a zoonotic parasitic infection that is endemic in many regions of the world. Musculoskeletal involvement, particularly in the thigh, is rare, accounting for approximately 1-4 % of all hydatid cyst cases. This case series aims to contribute valuable information by presenting three distinct cases of hydatid cyst affecting different compartments of the thigh.

CASES PRESENTATION: We detail the diagnostic process, surgical and medical management strategies, and outcomes observed during the follow-up period for each patient. The patients, including two livestock breeders from rural areas with close contact with sheep and dogs and one housewife from an urban area with no known animal contact, presented with a slowly enlarging mass in the thigh. Diagnosis involved clinical evaluation, advanced imaging techniques such as ultrasound and MRI, and serological testing. MRI revealed multiple cystic lesions with internal septations and daughter cysts in all cases. Serological tests for E. granulosus antibodies using ELISA were positive in two cases but initially negative in one. Treatment included pre-operative and post-operative albendazole therapy (10-15 mg/kg/day) and surgical excision of the cysts, with careful technique to avoid spillage and the use of scolicidal agents such as hypertonic saline, hydrogen peroxide, and povidone‑iodine.

DISCUSSION: Hydatid cyst of the thigh is a rare condition that often poses diagnostic challenges, as illustrated by an initial misdiagnosis of a Baker's cyst in one case. A high index of suspicion is necessary, especially in individuals from endemic regions or those with a history of animal contact, although cases can occur in urban residents with no known exposure. MRI is the gold standard for evaluating soft tissue hydatid cysts. Management requires a combined medical and surgical approach, with antihelminthic therapy and complete surgical excision of the cyst being critical components.

CONCLUSION: This case series highlights the diagnostic and management considerations for hydatid cyst of the thigh. The successful management of these three cases, with no recurrence observed during follow-up periods ranging from one to 1.5 years, underscores the importance of a multidisciplinary approach, early diagnosis, meticulous surgical technique, appropriate medical therapy, and diligent long-term follow-up for achieving favorable outcomes.