A challenging case of an intramedullary dermoid cyst of the cervical spine - A literature review

Abstract

A comprehensive differential diagnosis of intramedullary lesions of the sub-axial cervical spine must begin with the most common namely the diffuse fibrillary astrocytoma. Ependymoma's are not as common at this site and even rarer are epidermoids; teratomas; hemangioblastomas; lipomas, and drop metastases. Extremely rare lesions are intramedullary dermoid cysts and intramedullary schwannomas. We aimed to review the topic of intra-medullary dermoid cysts of the sub-axial cervical spine.Dermoid tumors are histologically distinct from epidermoids in that they are lined with dermis containing skin appendages for example hair and sebaceous glands. Epidermoids on the other hand are lined with stratified squamous epilthelium and contain only desquamated keratin. While congenital dermoid cysts account for only 1% of spinal cord tumors they are known to have a predilection for the lumbosacral spine. This predilection sees a 60% incidence at this site with only 10% occurring in the thoracic spine. A mere 5% of dermoid cysts occur in the cervical spine. Dermoid cysts are considered to be hamartomas that usually occur when mesodermal tissue becomes incorporated into the spinal canal during folding of the neural plate and the formation of the subsequent neural tube. While usually intra-dural and extramedullary in a dorsal location they do occur less commonly at an intramedullary site. An MRI is the diagnostic modality of choice and the features of fluid, soft tissue, calcium and fat are regarded as diagnostic of a dermoid tumor.Albeit rare dermoid cysts do occur at a purely intramedullary location in the sub-axial cervical spine and a comprehensive differential diagnosis must include this tumor type. Whilst displaying linear growth and not the exponential growth of a true tumor the cyst wall of these lesions demand meticulous resection techniques.