Skull Base Rhabdomyosarcoma
Rhabdomyosarcoma is a rare type of cancer that starts in skeletal muscle cells, the muscles that control all of your voluntary muscle movements. A rhabdomyosarcoma can form anywhere in the body. A skull base rhabdomyosarcoma forms in the head and neck, around the area where the spine connects to the skull. It may involve structures near the eyes or sinuses.
Facts about skull base rhabdomyosarcoma
Rhabdomyosarcoma is most common in children, but it is still quite rare, affecting only about four in 1 million children each year, and boys slightly more often than girls. Although adults can also get a rhabdomyosarcoma, that occurrence is even rarer. The vast majority of people who get this disease are younger than 15 years old.
About 40 percent of rhabdomyosarcomas develop in the head or neck, and about 15 percent of these cancers involve the base of the skull. Doctors do not know the cause of rhabdomyosarcoma, but some genetic conditions (meaning they are passed down through families) increase a child's risk. Genes may play a role in 10 to 30 percent of these cancers.
Genetic conditions that may be associated with rhabdomyosarcoma include Li-Fraumeni syndrome, neurofibromatosis, Beckwith-Wiedemann syndrome, and Costello syndrome.
Types of rhabdomyosarcoma
A rhabdomyosarcoma is categorized as one of two types:
Embryonal type is the most common, accounting for two-thirds of all cases. It is more common in younger children and is the most likely type to affect the base of the skull area.
Alveolar type is more common in teenagers and more likely to form in the arms or the legs. This type grows more quickly and is more likely to metastasize, or spread to other areas of the body.
Symptoms of rhabdomyosarcoma depend on the location of the cancer. Skull base rhabdomyosarcomas cannot be seen from the outside and may not cause any symptoms until they grow large or spread.
These are common symptoms:
Headache, ear, or eye pain
Nerve weakness or numbness in the head and neck area
Bulging or crossed eyes
Symptoms of rhabdomyosarcoma that has spread may include swollen nodes in the neck, bone pain, weakness, cough, and weight loss.
Diagnosis of skull base rhabdomyosarcoma begins with a complete history and physical exam. Imaging tests and blood tests are also important for making this diagnosis and for determining if the cancer has metastasized. These are important diagnostic studies:
X-rays of the skull and chest
CT scan of the skull base area
MRI of the base of the skull, considered the best test for detecting rhabdomyosarcoma
Bone scan, an imaging test to see if any cancer cells have spread to the bones
Lumbar puncture (spinal tap), in which a sample of spinal fluid is removed to check for cancer cells
Biopsy, in which a small sample of cancer cells is removed to examine under a microscope to make a more exact diagnosis
Once all the diagnostic studies have been done and the cancer has been seen under a microscope, it is possible to determine the best treatment.
These are the primary options:
Chemotherapy. Cancer-killing drugs are always used to help prevent a skull base rhabdomyosarcoma from coming back. Two or more types of chemotherapy drugs, given through an intravenous line, may be used.
Radiation therapy. Targeted X-rays may be used to kill cancer cells. Alveolar type cancers nearly always need radiation treatment. Radiation also may be added to chemotherapy in embryonal types if all of the cancer cannot be removed through surgery.
Surgery. Skull base cancers are difficult to reach. One approach that may be used is endoscopic endonasal surgery, involving a thin, lighted scope with a camera on the end. The surgeon can pass this scope through the nose to reach the base of the skull and operate through the scope to remove the cancer.
Your doctor will determine the most appropriate treatment or combination of treatments. Usually, all skull base rhabdomyosarcomas are treated with chemotherapy. Surgery is used to remove as much of the cancer as possible. If all of the cancer cannot be removed or if the cancer has spread, a combination of chemotherapy and radiation therapy may be used.
Managing skull base rhabdomyosarcoma
Skull base rhabdomyosarcoma usually occurs in children, and managing the disease involves a team of experts. Parents should learn as much as they can about this cancer and work closely with their child's doctors before, during, and after treatment. Follow-up care is important and may include blood tests and imaging studies to see if the cancer has returned. Psychological and social support can also greatly help both parents and children.