Primitive Neuroectodermal Tumor (PNET)

What are primitive neuroectodermal tumors?

A primitive neuroectodermal tumor (PNET) is a malignant tumor thought to develop from primitive (undeveloped) nerve cells.

PNETs usually develop in the central nervous system and are located in the cerebrum.

These tumors tend to spread easily through cerebrospinal fluid.

PNETs are the most aggressive kinds of tumors found in children.

There are different types of PNETs including medulloblastoma, pineoblastoma, and central nervous system PNET; each are classified by their location in the brain.

What causes primitive neuroectodermal tumors? Who is affected?

During the normal development of a fetus, the primitive nerve cells develop into neurons (nerve cells) which is a process that continues well into adulthood. In some cases, these cells become tumors.

The exact cause of PNETs remains unclear.

Those who have had previous cranial irradiation (exposure to radiation) are at an increased risk of developing a PNET.

PNETs are usually found in infants, children, and young adults under the age of 25.

What are the symptoms of PNETs?

PNETs are aggressive tumors that attach to parts of the brain responsible for movement, thought, and sensation.

Symptoms depend on the location of the tumor and may include headache, nausea, vomiting, fatigue, lethargy, seizures, changes in behavior or personality, and weakness on one side of the body. Each child will experience these symptoms differently.

How are PNETs treated?

Surgery is used to treat and biopsy a tumor to determine a diagnosis and treatment plan.

Surgeons may perform additional procedures if the tumor causes a blockage of cerebral spinal fluid (CSF). Surgeons create a small hole to relieve symptoms of hydrocephalus, the buildup of fluid inside the skull. In some cases, children may have ventriculoperitoneal shunt (VP shunt) surgically placed so excess fluid can drain into the abdomen. Reducing the pressure caused by fluid build-up will help control the symptoms of a brain tumor.

Children will likely receive chemotherapy and/or radiation therapy to shrink the tumor and kill any remaining cancer cells.

For children younger than 3, doctors usually avoid radiation therapy due to its long-term damaging effects.