Simple bone cyst in cervical vertebral spinous process and laminae: report of a case.

Simple (unicameral or solitary) bone cysts are the only true cysts of primary intraosseous origin. These cysts involve the metaphysis of long tubular bones such as the proximal humerus and proximal femur and, occasionally, the proximal tibia, distal femur, patella, ilium, rib, and calcaneus. They are very rarely found in vertebrae, especially in the cervical vertebral spinous process and laminae. We report a 14-year-old boy with an expansile, bubbly cystic lesion in the spinous process and laminae of the seventh cervical vertebra. Histopathologic examination showed a cyst surrounded by thin fibrous or fibro-osseous wall without any lining epithelial cells, compatible with a simple bone cyst. As far as we know, this is the first case of simple bone cyst involving the spinous process and laminae of a cervical vertebra reported in Taiwan.