Introduction: Aneurysmal bone cyst (ABC), comprising 1.4% of all primary bone tumors and 15% of all primary spine tumors, is a rare benign tumor. It is pathologically characterized by cystic, blood-filled spaces surrounded by thinned out cortical bone. Thoracic (32%) and lumbar spine (34%) involvement is common.

Observation: we report the case of a previously healthy 2 year-old boy, with insidious onset, gradually progressive painful spastic sensori-motor paraparesis, evolving since 8 days predominant in the right side. We note a spinal syndrome with sensory level at T6. The vesical dysfunction are not evaluated because of the young age of the patient.

MRI of the spine showed a low-to-intermediate signal intensity, heterogeneous mass with multiple fluid levels invading the posterior arc of the third thoracic vertebra. It was extending into posterior epidural space at D2 through D5 level causing cord compression without myelopathic changes. A D2, D3, D4 laminectomy with near total excision of mass was performed. During surgical exploration of the spine, a grayish fleshy mass, with multiple cysts filled with blood, was removed and sent for histopathology which confirmed the diagnosis of aneurysmal bone cyst.

Conclusion: ABC is a benign tumor that can present with a wide variety of non-specific symptoms. Neurological deficits are not uncommon. Early diagnosis and careful surgical planning is essential. Surgical decompression can lead to significant improvement even in case of severe neurological deficit.