Overview

Embryonal tumors of the central nervous system are cancerous (malignant) tumors that start in the fetal (embryonic) cells in the brain. Embryonal tumors can occur at any age, but most often occur in babies and young children.

Types of embryonal tumors include:

• Medulloblastomas. The most common type of embryonal tumor, these fast-growing cancerous brain tumors start in the lower back part of the brain, called the cerebellum. The cerebellum is involved in muscle coordination, balance and movement. Medulloblastomas tend to spread through cerebrospinal fluid (CSF) to other areas around the brain and spinal cord, though they rarely spread to other areas of the body.
• Embryonal tumors with multilayered rosettes (ETMRs). Rare tumors that are cancerous, ETMRs typically occur in infants and young children. These aggressive tumors most often start in the largest part of the brain, called the cerebrum, which controls thinking and voluntary movement. ETMRs can also occur in other parts of the brain and are often characterized by a certain genetic change.
• Medulloepitheliomas. These rare, fast-growing cancerous tumors typically occur in the brain or spinal cord of infants and young children.
• Atypical teratoid/rhabdoid tumors. These rare, cancerous tumors are most often found in the cerebellum of infants and children under 3 years of age.
• Other embryonal tumors. A category called embryonal tumors not otherwise specified includes most cancerous tumors that were formerly called primitive neuroectodermal tumors (PNETs), occurring in the brain and spinal cord.

Signs and symptoms of embryonal tumors vary, depending on the type of tumor, location, severity and other factors, such as pressure buildup within the brain. Symptoms may include, for example, headaches, nausea, vomiting, unusual tiredness, dizziness, double vision, unsteady walk, seizures or other issues.