Osseous hydatid disease is defined as development within bone of multiple cysts that are the larval form of the tapeworm Echinococcus granulosus. Bone cysts account for only 0.5-2.5% of all hydatid cysts in humans. We report on our experience.

Methods. - This retrospective study included patients managed between 1988 and 1998 for histologically documented hydatid disease of bone.

Results. - Eleven patients were included, six men and five women, with a mean age of 40.7 ± 11.04 years (range, 27-60 years). Mean time to diagnosis was 22.7 ± 18.2 months (range, 5-36). The pelvis was involved in six patients and a long bone in five (the femur in three, the tibia in one, and the fibula in one). Peripheral eosinophil counts were high in four patients and serological tests for hydatid disease were positive in five patients. Surgical treatment was used alone in 10 patients and with albendazole in one patient. The main complications were fistulization (n = 6) and suppuration (n = 4). Five patients experienced recurrences.

Conclusion. - Hydatid disease still occurs in Morocco. The liver and lungs are the most common targets. Bone cysts are uncommon but severe. The behavior of osseous hydatid cysts resembles that of locally malignant lesions. Although immunofluorescent assays are useful, the final diagnosis depends on histology. The treatment rests on surgical excision. Recurrence is common, particularly at sites that are difficult to access.