Tehran University Medical Journal

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Background: Hydatid disease or echinococcosis is a common parasitic disease of human and bovine, caused by infection with larva of the cestode echinococcus. Liver is the most common organ that is involved in this disease. Pelvic involvement and neurological symptoms, due to mass effect of pelvic involvement, in lower extremities are very uncommon manifestations of the disease.
Case presentation: A forty six year old man was referred to clinic of surgery at Ghaem Hospital, Medical University of Mashhad, Iran. The patient complained about weakness and motor impairment in right lower extremity accompanied by numbness and radicular pain over past two months. Physical examination demonstrated muscular atrophy and reduced muscular strength in right lower extremity. Computed tomography and ultrasonographic studies showed a cystic mass in right side of the pelvic cavity with extention to the sciatic notch and another cystic mass in right gluteal region. Surgical operation revealed a cystic mass deep in pelvic cavity with the extention to the right sciatic notch with compression of nerve roots. The cystic mass was contained of daughter cysts which confirmed the diagnosis of hydatid cyst disease. This diagnosis was confirmed by pathologic assessment.
Conclusion: Although uncommon, but hydatid disease can involve the pelvic cavity and make a pelvic, usually cystic, mass that can make compression on nerve roots and so making neurologic symptoms in lower extremities. So in endemic areas for hydatid disease, such as Iran, pelvic hydatid cysts should be considered as a possible differential diagnosis in patients presenting with the sciatic pain and neurological manifestations in whom a pelvic mass has been found too.