[Aneurysmal bone cyst of a lumbar vertebra in a child].

An aneurysmal cyst of the 3rd lumbar vertebra was diagnosed in a 6-year-old girl. She presented with right loin pain and a palpable mass in the region of the second and third lumbar vertebrae. X-ray of the vertebrae, but not computerized tomography, was characteristic for the tumor. The diagnosis was confirmed by histologic examination. Aneurysmal cyst of the vertebra is rare in children.