J Neurosurg Pediatrics 8:000–000, 2011 526 J Neurosurg: Pediatrics / Volume 8 / November 2011 H ydatid disease is a zoonotic infestation caused by the tapeworm Echinococcus granulosus, for which man is an intermediate host. It usually af- fects soft tissues, mainly the liver and the lungs (in about 90% of all cases). Bone hydatid cysts are very rare and occur in only 0.5%–2.5% of patients with hydatid cyst disease. Half of the cases of osseous hydatidosis have concomitant spinal involvement. 4,16 Characteristic ind- ings of hydatid disease are well known, but unusual imaging features and related complications are less fre- quently documented in the literature. 17,18 When the cysts do not show typical radiological features, the differential diagnosis is quite dificult and the lesion can mimic dif- ferent cystic pathologies. In this report, we present the case of a primary sacral extradural hydatid cyst with radiological features of an anterior meningocele. To the best of our knowledge, such a case has not been documented in the literature. Identi- ication of the cysts at surgery prompted the diagnosis. Case Report History and Examination. A 9-year-old boy was re- ferred to our neurosurgery outpatient clinic by a pediatric surgeon who had been consulted for chronic urinary re- tention that appeared 3 months prior to presentation. On admission, the patient presented with a 2-year history of progressive lumbago, bilateral sciatica, and paraparesis. Subsequently, a left-sided dropped foot developed, but the boy retained his ability to walk without assistance. Clinical examination revealed a conscious patient with a Glasgow Coma Scale score of 15. He was afe- brile, not pale, anicteric, and acyanotic with no signii- cant lymph node enlargement. Chest and cardiovascular systems were normal. The patient had a soft, cystic non- tender mass in the abdomen extending from the pelvis. The kidneys were not ballotable, and there was no renal angle tenderness. The patient had a self-retaining catheter with normal male external genitalia, normal anal sphinc- J Neurosurg Pediatrics 8:526–529, 2011 A sacral hydatid cyst mimicking an anterior sacral meningocele Case report Mustapha heMaMa, M.D., ali lasseini, M.D., loubna Rifi, M.D., Mahjouba boutaRbouch, M.D., saiD DeRRaz, M.D., abDessaMaD el ouahabi, M.D., anD abDeslaM el KhaMlichi, M.D. Service de Neurochirurgie, Hôpital des Spécialités O.N.O., Rabat, Morocco Hydatid disease is a zoonosis caused by Echinococcus granulosus. It is a progressive disease with serious morbidity risks. Sacral hydatid disease is very uncommon, accounting for < 11% of spinal hydatidosis cases. The di- agnosis of a sacral hydatid cyst is sometimes dificult because hydatidosis can simulate other cystic pathologies. The authors report on 9-year-old boy admitted to their service with a paraparesis that allowed walking without aid. The boy presented with a 2-year history of an evolving incomplete cauda equina syndrome as well as a soft cystic mass in the abdomen extending from the pelvis. Radiological examination revealed an anterior meningocele. A posterior approach with laminectomy from L-5 to S-3 was performed. Three lesions with classic features of a hydatid cyst were observed and removed. The diagnosis of hydatid cyst was conirmed histopathologically. Antihelmintic treatment with albendazole (15 mg/kg/day) was included in the postoperative treatment. The patient’s condition improved after surgery, and he recovered normal mobility. The unusual site and presentation of hydatid disease in this patient clearly supports the consideration of spinal hydatid disease in the differential diagnosis for any mass in the body, especially in endemic areas. (DOI: 10.3171/2011.8.PEDS10555) Key WoRDs • anterior meningocele • hydatid cyst • posterior approach • sacrum • surgery • spine