Hydatid Disease With Psoas and Gluteal Muscle Involvement Causing Cauda Equina Compression: A Case Report.

Hydatid disease is a zoonotic infection caused by the tapeworm, primarily affecting the liver and lungs, and rarely involving muscle tissue. Humans are infected by ingesting eggs from contaminated food or water. Patients may present with painless, slow-growing masses, sometimes associated with nerve or vessel compression, especially in cases of muscle involvement. Diagnostic imaging techniques such as ultrasonography, CT scan, and MRI are essential for preoperative evaluation. Treatment involves surgical removal of the cyst with careful lavage to prevent recurrence, followed by anti-parasitic medication. Our case involves a young female with a previously treated pulmonary hydatid cyst, who presented later with numbness and pain in her left lower limb, revealing a psoas location of hydatid disease exerting direct compression of the cauda equina. This case underscores the importance of including hydatid disease as a potential differential diagnosis for soft tissue masses in endemic areas, even with an atypical clinical presentation.