Primitive Neuroectodermal Tumors (PNET)

Primitive neuroectodermal tumors (PNET) and pineoblastoma are a group of tumors defined by their appearance and are thought to develop from primitive (undeveloped) nerve cells in the brain. They appear similar to medulloblastoma and were once considered a single tumor.

PNETs and pineoblastomas are aggressive tumors that tend to attach to parts of the brain that control movement, thought, and sensation. Scientists have not been able to find an identifiable cause or risk factors for these tumors. There doesn't appear to be a genetic predisposition, meaning that these diseases do not seem to run in families.

Symptoms depend on the location of the tumor — each child may experience symptoms differently. Common symptoms include headache, nausea, fatigue, seizures, behavior or personality changes, unexplained weight loss or gain, difficulty looking upward, or weakness on one side of the body.

Your child’s physician may order a number of different tests to best diagnose a tumor. In addition to a physical exam, medical history, and neurological exam (which tests reflexes, muscle strength, eye and mouth movement, coordination, and alertness), your child’s doctor may request other tests, including diagnostic imaging.

Since these tumors are known to spread via cerebrospinal fluid, there is a high chance that they will invade other tissues of the brain and spine, so it is essential that your child have an MRI of both the brain and spine.

After all necessary tests are complete, the best treatment options can be identified.

Your child’s physician will determine a specific course of treatment based on several factors. Some therapies will treat the tumor while others are intended to address complications of the disease or side effects of the treatment. These treatments include neurosurgery, radiation therapy, or chemotherapy.

If your child has hydrocephalus another procedure, called ETV (endoscopic third ventriculostomy), may be necessary. There have been reports of these tumors traveling through shunts into the peritoneal cavity; therefore, all efforts are made to avoid shunt placement in these children.

There can be side effects related to the tumor itself or its treatment. Knowing what these side effects are can help your care team prepare for and, in some cases, prevent these symptoms from occurring.

Patients with PNETs and pineoblastoma are treated at Dana-Farber/Boston Children's Cancer and Blood Disorders Center through the Medulloblastoma Program.