Types of Brain Tumor Related Cysts

The subject of cysts contains a number of separate entities. These include arachnoid cysts, colloid cysts, dermoid cysts, epidermoid cysts and Rathke's cleft cysts. The symptoms of these various cysts relate to their size, location and speed of growth. They are all benign.

Arachnoid cyst

These are also known as leptomeningeal cysts. They are congenital lesions present from the time of birth). As mentioned above, their symptoms relate to their size, location and speed of growth. They are often found incidentally when a CT scan or MRI scan is obtained for another reason. Treatment options include observation (with serial CT or MRI scans), cyst-peritoneal shunt (drainage to the abdominal cavity) or craniotomy with resection of the cyst. The particular treatment recommended depends upon the symptoms and location.

Colloid cyst

These are also known as neuroepithelial cysts. Colloid cysts almost always occur in adults. They are most commonly found in the third ventricle (a central portion of the spinal fluid pathway). This location can, if the cyst is large enough, cause blockage of the spinal fluid and lead to hydrocephalus. This leads to an increase in intracranial pressure, the symptoms of which range from simple headache to sudden death. The diagnosis is made by MRI scan. CT scan can also show these cysts but MRI is preferable. There are a number of treatment options. One option is a shunt procedure to drain the excess spinal fluid to the abdominal cavity. Direct approaches to the tumor include a number of larger cranial operations and two "smaller" approaches. One, stereotactic aspiration and two, endoscopic aspiration/removal. Since the best approach has yet to be determined, treatment is decided on an individual case basis.

Dermoid cyst

The dermoid cyst is a benign tumor that originates from some of the cells that later form the skin. They are more commonly seen in the spine than the brain. When found in the brain, they tend to be in the midline. Dermoid cysts are usually seen in children and can be associated with episodes of meningitis. The treatment is surgical removal.

Epidermoid cyst

The epidermoid cyst is also known as a cholesteatoma. Like the epidermoid cyst they also originate from the cells that later form the skin. These cysts are found most commonly in middle-aged adults. Unlike dermoid cysts, epidermoid cysts are more frequently located in the brain than the spine. Epidermoid cysts tend to be located in an area called the cerebello-pontine angle (the usual location for acoustic neuromas). The standard treatment is surgical removal.

Rathke's cleft cyst

These are developmental cysts that arise from cells located in what is called Rathke's cleft or pouch. Rathke's cleft cysts are found in the region of the pituitary gland and are frequently seen as incidental findings at autopsy. Rathke's cleft cysts cause symptoms by causing pressure on adjacent structures such as the optic nerves (causing vision problems) and the pituitary gland causing loss of pituitary function. The treatment, when they cause symptoms, is surgery.

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