Osseous hydatid disease.

Hydatid disease is still endemic in several regions worldwide and is caused in most cases by the larval form of two species of the tapeworm Echinococcus: E. granulosus and E. multilocularis. Bone involvement is rare (0.2-4%), affecting the spine in almost half of the cases. The disease is usually silent until a complication (e.g. paraplegia or pathologic fracture) occurs. Many cases are diagnosed intraoperatively. Pre-operative diagnosis is based on radiological findings and serological assays, which lack high sensitivity and specificity. A high index of suspicion is necessary for the diagnosis, especially in patients that live in or travel to sheep-raising areas where hydatid disease is endemic. The treatment of choice is surgical, following the principles of a locally malignant lesion. Chemotherapy (albendazole alone or in combination with praziquantel) is used as an adjuvant treatment or when surgery is not possible. The prognosis is often poor, especially in the spine: most patients do not recover neurologically, the mortality and complication rate is high and many cases recur, as it is often impossible to radically excise the pathologic tissue.