A cyst is a sac of tissue filled with another substance, such as air or fluid. Cysts can form in all parts of the body, including the brain.
A cyst may appear similar to a tumor externally, but they have very different causes. A tumor is a solid mass of tissue, and a cyst is a sac filled with a substance.
This article examines the six main types of cyst that can appear in the brain.
A cyst is a hollow sac containing liquid, pus, air, or cells.
Most cysts are benign, or noncancerous, but they can sometimes cause issues if they press on surrounding organs, tissues, or nerves.
The six main types of brain cysts are arachnoid, pineal, colloid, dermoid, epidermoid, and neoplastic.
These cysts develop on the arachnoid membrane. This membrane covers the brain and spinal cord along with two other membranes. Cysts that grow on the arachnoid membrane are usually benign and rarely cause symptoms. However, if symptoms do develop, they include:
Spinal arachnoid cysts can create progressive weakness in the legs or numbness in the hands or feet.
Because most arachnoid cysts do not cause symptoms, doctors usually identify them during an MRI or CT scan for a different issue. Most doctors will not recommend any treatment or surgery unless the cyst is causing symptoms.
If a doctor decides treatment is necessary, they will perform surgery to drain the fluid, which the surrounding tissue will absorb.
Pineal cysts are fluid-filled spaces within the pineal gland. The pineal gland sits near the center of the brain and regulates sleep cycles.
Most pineal cysts are benign and cause little to no symptoms. According to an
Most pineal cysts will not require surgical removal. However, a doctor might suggest surgery if the cysts become larger than 2 centimeters.
Surgery involves making a small hole in the cyst to release the fluid, which will drain into the brain’s fluid spaces.
Colloid cysts develop in the ventricles of the brain. Ventricles are open cavities in the brain full of cerebrospinal fluid.
Colloid cysts are benign, but they can block the flow of cerebrospinal fluid, leading to an excess of fluid in the brain. This is called hydrocephalus. Symptoms of hydrocephalus include
- a headache
- double vision
- memory issues
- difficulty concentrating
- altered states of consciousness and even coma in some advanced stages
Doctors treat colloid cysts with a minimally invasive procedure that removes the cyst via endoscopy.
Dermoid cysts develop from a congenital abnormality in the skin cells.
They occur when the skin layers do not grow together as they should during fetal development. Dermoid cysts are present at birth in the brain or spine.
The cyst consists of tissue under the skin that can include hair follicles, oil glands, sweat glands, and sometimes, bone, teeth, or nerve cells.
While they typically do not cause any symptoms and are not cancerous, most doctors will use surgery to remove the cyst soon after birth.
Unlike dermoid cysts, epidermoid cysts contain simple skin cells, including keratin and dead skin cells.
They occur on the spine when the body accidentally sheds skin cells internally, creating a slowly growing cyst.
While epidermoid cysts themselves are not dangerous, they may compress the spinal cord or spinal nerves as they grow. Epidermoid cysts may cause:
- reduced coordination
- tingling in the arms and legs
- mobility problems
A doctor will usually remove the cysts using microsurgery techniques.
While some cysts can have associations with tumors and cancer, most cysts are benign. Sometimes, as brain tumors and cancers grow, they can cause a cyst to form.
Typically, most brain cysts are benign and do not require surgical removal.
If surgery is necessary, the surgeon will either drain or remove the cyst.
Many brain cysts are congenital, but sometimes, they can indicate an underlying condition, such as cancer or an infection.