A spinal tumor is defined by the abnormal proliferation of cells that grow within or around the spinal cord or the bony vertebral column. While the public often uses the general term “spinal cancer,” this broad phrase encompasses a diverse group of specific medical conditions. Medical professionals rely on precise nomenclature and classification systems to identify these growths based on their origin, location, and the type of cells involved. These distinctions in medical terminology are significant because they guide diagnostic procedures and inform treatment strategies.
Understanding Primary and Secondary Spinal Tumors
The fundamental distinction in spinal tumor diagnosis is based on where the growth originated. Primary spinal tumors begin directly within the tissues of the spinal cord, surrounding nerve roots, or the vertebral bone itself. These tumors are relatively uncommon, representing a small fraction of all growths found in the spine. Primary tumors can be either benign (non-cancerous) or malignant (cancerous), though malignant primary spinal tumors are the least common type overall.
Secondary spinal tumors, also known as metastatic tumors, are vastly more prevalent. These growths begin as cancer elsewhere in the body and then spread to the spine, often traveling through the bloodstream. Secondary tumors account for approximately 97% of all spinal tumors. Cancers that most frequently spread to the spine include those originating in the lung, breast, and prostate. Because they have spread from another site, secondary tumors are nearly always malignant.
Anatomic Classification of Spinal Tumors
Beyond the origin, medical classification specifies a tumor’s location relative to the spinal cord and its protective layers. The spinal cord is protected by the dura mater, a tough membrane that forms a fluid-filled sac around the nervous tissue. Tumors are categorized based on their position outside or inside this dural sac.
The largest group of spinal tumors is classified as extradural, meaning they are located outside the dura mater. These tumors frequently involve the bony vertebrae and are most often metastatic growths. Extradural tumors account for 55% to 60% of all spinal tumors. They tend to compress the spinal cord from the outside.
Tumors that lie inside the protective dural membrane are collectively called intradural tumors. This category is further subdivided based on the tumor’s relationship to the actual spinal cord tissue. Intradural tumors make up the remaining 40% to 45% of spinal tumors.
A tumor that is inside the dura but remains outside the substance of the spinal cord is termed intradural-extramedullary. These growths typically arise from the inner lining of the dura mater or the nerve roots that branch off the spinal cord. Representing about 40% of intradural tumors, they exert pressure on the spinal cord without invading the tissue.
The least common type is the intradural-intramedullary tumor, which grows directly within the spinal cord tissue. These tumors are particularly challenging because they often infiltrate the delicate nerve fibers. They account for the remaining 5% to 10% of all spinal tumors.
Common Medical Names for Spinal Cancers
The final layer of medical naming identifies the specific cell type from which the tumor arose, providing the histological diagnosis. For primary tumors developing within the spinal cord tissue (intramedullary), the two most common types are Ependymomas and Astrocytomas. Ependymomas originate from the ependymal cells lining the central canal of the spinal cord. Astrocytomas develop from astrocytes, which are supportive glial cells within the nervous system. These two types account for the majority of intramedullary growths.
In the intradural-extramedullary space, the most frequent primary tumors are Meningiomas and nerve sheath tumors. Meningiomas grow from the meninges, the protective layers surrounding the spinal cord. Nerve sheath tumors, such as Schwannomas and Neurofibromas, arise from the Schwann cells that form the insulating sheath around nerve roots.
For secondary spinal tumors, the naming convention relates back to the original source of the cancer. They are named after the tissue they spread from, such as Metastatic Lung Carcinoma or Metastatic Breast Cancer to the spine. Medical professionals use this precise naming system regardless of whether a tumor is classified as benign or malignant.