The skull base is the area behind the eyes and nose that slopes down to the back of the head. It forms the floor, or base, of the skull. The spinal cord, multiple nerves and the major blood vessels of the brain, head and neck pass through openings in the skull base.
Not all tumors in the skull base are malignant (cancer). Even benign (non-cancerous) tumors can cause symptoms or threaten the health and well-being of the patient.
Tumors of the skull base are categorized based on the unique characteristics and cell structure of each type. Tumor typing is determined during the patient's diagnostic workup. Radiologists and pathologists who have special expertise in tumors of the head and brain work closely with the head and neck surgeons and the neurosurgeons to determine tumor type.
The tumor type, together with the unique health profile and needs of each patient, helps the skull base team specifically tailor treatment for each patient.
The most common malignant skull base tumors include:
- Adenoid cystic carcinoma
- Esthesioneuroblastoma or olfactory neuroblastoma
- Nasopharyngeal carcinoma
- Non-Hodgkin’s lymphoma
- Squamous cell carcinoma
Other malignant skull base tumors:
- Endolymphatic sac tumor
- Mucoepidermoid carcinoma
- Myeloma/plasma cell tumors
- Neuroendocrine carcinoma
- Sarcomas. The more common sarcomas are as follows:
- Ewing's sarcoma
- Sinonasal undifferentiated carcinoma
The most common benign skull base tumors include:
- Acoustic neuroma (vestibular schwannoma)
- Meningioma (the most common skull base tumor)
- Pituitary tumors
Other benign skull base tumors:
- Cholesterol granuloma, epidermoid and dermoid cysts
- Fibro-osseous lesions. These include the following:
- Fibrous dysplasia
- Ossifying fibroma
- Inverting Papilloma
- Carotid body tumors
- Glomus jugulare
- Glomus tympanicum
- Glomus vagale
- Jugular foramen schwannoma
- Trigeminal schwannoma
Head and neck tumors may also extend to the skull base. Examples include:
- Salivary gland tumors. (The most common types of salivary gland cancers are mucoepidermoid carcinoma and adenoid cystic carcinoma.)
- Skin cancers such as squamous cell carcinoma, melanoma and basal cell carcinoma that can travel along nerves and spread to the brain and skull base
Skull Base Tumor Risk Factors
Anything that increases your chance of getting a skull base tumor is a risk factor. Since skull base tumors are rare, risk factors are hard to determine.
Previous exposure to ionizing radiation and certain occupational exposures have been identified as risk factors for meningioma, some sarcomas and certain sinonasal malignancies. Exposure to wood dust, heavy metals and a history of working with leather are also risk factors for developing some sinus and nose cancers. Certain types of nasopharyngeal cancers are related to childhood exposure with the Epstein-Barr virus.
Sometimes, inherited genetic conditions are linked to skull base tumors. In these cases, our genetics experts are part of the patient’s care team. The types of tumors that may be caused by genetic conditions include:
Bilateral acoustic neuromas, as well as other brain and spine tumors, may be caused by the genetic disorder neurofibromatosis type 2.
Paragangliomas (also called glomus tumors or carotid body tumors) may be caused by a familial predisposition for other tumors.
Pituitary tumors may be associated with multiple endocrine neoplasia 1 (MEN1) or family isolated pituitary adenoma (FIPA) which may be familial and predispose to other tumors.
Not everyone with risk factors gets skull base tumors. However, if you have risk factors, it’s a good idea to discuss them with your doctor.
Research shows that many cancers can be prevented.
Some cases of skull base tumors can be passed down from one generation to the next. Genetic counseling may be right for you. Learn more about the risk to you and your family on our genetic testing page.