RESUMEN
Eating the egg of Echinococcus granulosus tapeworm in vegetables contaminated with dog's fecal material is the main cause of hydatid cyst. The most common involved organ is liver and the second are lungs. Spinal involvement especially primary involvement of paravertebral soft tissue without vertebral and extradural involvement is very rare. We report a case with paravertebral hydatid cyst without vertebral involvement. A 61 years old man patient resident of Torbatjam, Khorasan Razavi provience, was admitted to our department complaining a mass in back from six years ago. In physical examination he had several right paravertebral masses. MRI reveals a huge multilocular mass in the right paraspinal from T1 to L5 that is accompanied by ribs erosion without destruction. Operation was performed and the cyst was completely removed while contained several liquid-filled cysts, the hydatid-like cysts. Pathological findings were confirmed the diagnosis. Albendazole [10mg/kg] was prescribed postoperatively for six months. Recurrence has not occurred after two years follow up. Hydatid disease is a major infectious disease that is a main problem in many countries. In some articles paravertebral involvement without vertebral and extradural involvement is reported but primary paravertebral involvement with hydatid cyst is very rare. In this case we report paravertebral without vertebral involvement and the patient did not show any sign of spinal and vertebral pressure. In spite of the fact that hydatid cyst involves liver and lungs more than other organs, it can involve any organ and this point should be taken into consideration especially in the endemic areas.