EC Orthopaedics

Hydatid disease of the sacroiliac (SI) joint is a rare manifestation of Echinococcus granulosus infection, presenting with nonspecific symptoms and challenging imaging findings. We report a 60-year-old male with progressive left pelvic pain radiating to the leg, difficulty walking, and occasional numbness over 8 months. Laboratory tests were largely unremarkable, except for positive Echinococcus IgG serology. Radiographs showed lytic lesions in the left iliac bone, while MRI revealed multiloculated cystic lesions with T1 hypointense and T2 hyperintense signals, demonstrating the “water lily sign”. The patient underwent surgical debridement and albendazole therapy, with uneventful recovery. MRI is essential for accurate assessment, and early recognition allows timely surgical and medical management to reduce recurrence.

 Keywords: Sacroiliac Joint; Hydatid Disease

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