Pleomorphic Xanthoastrocytoma (PXA) and Anaplastic Pleomorphic Xanthoastrocytoma (APXA)
Pleomorphic xanthoastrocytoma (PXA) and anaplastic pleomorphic xanthoastrocytoma (APXA) are two types of very rare astrocytomas. They are primary central nervous system (CNS) tumors. This means they begin in the brain or spinal cord.
What are the grades of PXA and APXA?
The tumors are grouped in two grades based on their characteristics.
- Grade II PXAs are low grade tumors. This means the tumor cells grow slowly.
- Grade III APXAs are malignant (cancerous). This means they are fast-growing tumors.
Who is diagnosed with PXAs and APXAs?
PXAs and APXAs can occur at any age, but tend to happen in young adulthood, and affect men and women equally. PXAs and APXAs are more common in people of African descent.
What causes PXAs and APXAs?
The cause of most PXAs and APXAs is not known. People with gene changes that can be passed down through families such as neurofibromatosis type I and familial melanoma/astrocytoma syndrome, are at increased risk for developing PXAs and APXAs.
Where do PXAs and APXAs form?
PXAs and APXAs usually occur in one of the four lobes of the brain. The temporal lobe is the most common location. Rarely, PXAs and APXAs can form in the cerebellum, brainstem, and spinal cord. PXAs and APXAs are usually located close to the surface of the brain tissue. Scientists believe these tumors arise from cells that grow into glial and nerve cells. PXAs and APXAs can look a variety of ways under the microscope and can be challenging to diagnose, as they share characteristics with other primary brain tumors. Review by an expert neuropathologist is recommended to confirm this diagnosis. Molecular testing will often reveal a BRAF gene change in these tumors.
Do PXAs and APXAs spread?
PXAs are slow-growing tumors that usually don’t spread. APXAs are fast-growing tumors that usually invade brain tissue in the lobe of the brain where they started. It’s rare for APXAs and PXAs to spread to other areas of the CNS. There are no reported cases of spread outside of the CNS.
What are symptoms of a PXA or APXA?
Symptoms related to PXAs and APXAs depend on the tumor’s location. People with PXAs may have seizures, epilepsy, and chronic headaches. People with APXAs may have seizures, weakness, numbness, and speech and language changes.
What are treatment options for PXAs and APXAs?
The first treatment for a PXA and APXA is surgery, if possible. The goal of surgery is to obtain tissue to determine the tumor type and to remove as much tumor as possible without causing more symptoms for the person. PXAs can often be treated by surgery alone.
If they come back after surgery, there is no standard treatment for PXAs and APXAs. Possible treatments at this time may include radiation, chemotherapy, targeted therapies, or clinical trials. If a BRAF change is present, clinical trials using a drug to target that may also be an option. Treatments are decided by the patient’s healthcare team based on the patient’s age, remaining tumor after surgery, tumor type, and tumor location.
What do PXAs and APXAs look like on an MRI?
PXAs often form fluid-filled cysts in a mural nodule, which means a cyst within solid tissue with a dense appearance on MRI. APXAs may appear similar to PXAs, but the way they look varies and makes it difficult to tell apart from other primary CNS tumors. The diagnosis of PXA or APXA can’t be made by imaging alone because they look the same as glioblastomas and other high-grade brain cancers.