What Is Pilocytic Astrocytoma?

Medically Reviewed by Sabrina Felson, MD on February 23, 2024
3 min read

A pilocytic astrocytoma (PA) or juvenile pilocytic astrocytoma (JPA) is a tumor in the primary central nervous system (CNS). It refers to abnormal growth of the brain and spinal cord cells that make up the CNS.

A pilocytic astrocytoma affects the astrocytes of the brain or spinal cord. These are non-nerve cells that nourish your CNS. PA tumors are usually slower-growing than other tumors of the astrocytes. 

The term "astro" means "stars." PA starts in the star-shaped astrocytes of our brain and spinal cord.

This type of tumor is slow-growing and usually starts in childhood. Some adults may also develop PA.

‌PAs usually don't affect other tissues. Some healthcare specialists overlook them since they are not life-threatening cancers. In fact, PAs are the most treatable and benign (tumors that do not spread to other cells) form of glioma, a cancer with different cell types. But often, mild cancers can cause problems in the future and may damage central nervous system tissues.

The exact cause of a pilocytic astrocytoma is still unknown. But some researchers believe that genetic conditions can cause these tumors. These conditions can be:

  • Li-Fraumeni syndrome, an inherited condition that increases the risk for certain cancers 
  • Nevoid basal cell carcinoma syndrome
  • Neurofibromatosis types 1 and 2
  • Tuberous sclerosis complex
  • Turcot syndrome 

Some immunologic and environmental factors may also cause pilocytic astrocytomas, including:

  • Exposure to ultraviolet (UV) rays
  • Contact with certain chemicals
  • Ionizing radiation

Studies into the cause of PAs are ongoing. ‌

Pilocytic astrocytoma symptoms depend on the size and location of the central nervous system tumor. If the tumor is small, it won't cause any visible symptoms. But if it's large enough to press on the nearby tissues, it can cause severe symptoms. 

PAs usually grow in the lower back of your brain, known as the cerebellum. The cerebellum manages your body's balance and coordination. Some PAs may also grow near the optic nerve that may affect your vision. 

Other PAs can also restrict the usual cerebrospinal fluid (CSF) flow. The fluid performs several functions for your brain and spinal cord. It serves as a cushion, delivers nutrients, and removes waste materials from your brain.

The abnormal build-up of CSF may cause high pressure on the brain, known as intracranial pressure. 

This may lead to: 

  • Balance problems
  • Vision problems
  • Seizures (that are not due to the fever)
  • Headache 
  • Trouble walking 
  • Nausea and vomiting 
  • Dizziness
  • Behavior changes
  • Delays in development
  • Fatigue
  • Coma
  • Unusually fast growth of the head (in infants)

Most of these symptoms can also be caused by other medical problems. So it's essential to visit your doctor as soon as you notice any of these symptoms. 

A tumor causes problems when it starts pressing on brain tissues. When PA becomes problematic, your doctor may recommend treatment.

The common pilocytic astrocytoma treatment methods are:

Radiation therapy or chemotherapy. If the tumor isn't removed in surgery, the doctor opts for one (or many) therapy sessions. They include radiation therapy, chemotherapy, or targeted therapy. These therapies are used primarily on adults to kill any tumor cells left after the surgery. 

Infants and younger children won’t get radiotherapy, but will likely get chemotherapy after surgery to kill remaining cancer cells. 

Post-surgery treatment. Your doctor will wait to see if the tumor comes back after surgery or not. One reason is the slow growth of PAs. Another reason is that radiation therapy may be riskier than the PA growing back.

In some people, a PA can also block the cerebrospinal fluid (CSF) flow from your brain. When this happens, the CSF tends to build up in the brain. 

In such cases, the doctor will perform a surgery to insert a tube called a shunt to clear the CSF passage. When the CSF drains away, the shunt is removed.

The treatment for a PA requires follow-up. You will need to stay in touch with your doctor even after the treatment. This is to see if the tumor is coming back or not.‌

The follow-up visits to the doctor include magnetic resonance imaging (MRI) to get a clear picture of the tumor. These visits usually continue for years.