Neurofibroma

What is a neurofibroma?

A neurofibroma is a common non-cancerous type of tumour that starts from the cells normally found in a nerve. It can occur at any age and in any location in the body.

What is a nerve?

Nerves are like long wires made up of groups of cells called neurons. Nerves transmit information (such as temperature, pressure, and pain) between your brain and your body. Nerves are found throughout your body. Some nerves are very small (like those just under the surface of the skin) while others are very large (like those that go to muscles).

Syndromes associated with neurofibromas

Patients with the genetic syndrome neurofibromatosis type 1 (NF1) are at high risk for developing multiple neurofibromas. Neurofibromas that develop in patients with NF1 are also more likely to change over time into a type of cancer. Pathologists describe this as a transformation. The most common type of cancer to arise from a neurofibroma in a patient with NF1 is called a malignant peripheral nerve sheath tumour.

How do pathologists make this diagnosis? 

A pathologist may make a diagnosis of neurofibroma after a small sample of the tumour is removed in a procedure called a biopsy. Or a pathologist may make the diagnosis of neurofibroma if it is removed completely at first, without a biopsy.

Under the microscope, neurofibromas are made of spindle cells that look very similar to the cells in a normal nerve.  These non-cancerous tumours are usually easy to separate from the surrounding normal tissue. Because they are attached to a nerve, these tumours can cause symptoms such as pain or tingling.

Types of neurofibromas

Pathologists divide neurofibromas into different types depending on where in the body the tumour starts and how the tumour grows.

• Cutaneous neurofibroma – These tumours develop close to the skin.
• Intraneural neurofibroma – These tumours develop on the inside of a nerve.
• Diffuse neurofibroma – These tumours tend to grow a little deeper into the fat just below the skin.
• Plexiform neurofibroma – These tumours have an irregular shape and are often associated with neurofibromatosis type 1.

by Bibianna Purgina MD FRCPC (updated September 13, 2021)