Nevus Outreach, Inc., The association for Large Nevi and related disorders.
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CMN Glossary

This guide was designed to help you understand the terminology you may encounter with regard to large/giant congenital nevi (CMN) and neurocutaneous melanocytosis (NCM). It briefly defines in layman’s terms the technical terminology used by doctors and medical professionals. If you have further questions after reviewing this glossary, please contact your doctor or Nevus Outreach.

Biopsy Removal of a small piece of tissue for microscopic examination for diagnostic purposes.

Brain Regions


An illustrated cross-section of the human brain with each part labeled.

Cancer Uncontrolled growth of cells.

Congenital Present at birth or within the first year of life.

Contrast A substance, or dye, given in the vein, to enhance the MRI or CT films.

CT Scan (Computed Tomography) Also called CAT (Computed Axial Tomography) A diagnostic tool for the examination of the body, such as the brain. CT is generally less expensive but less sensitive than MRI in detecting abnormalities.

Cultured Epithelial Autografts See cultured skin.

Cultured Skin One limited option of treatment for a nevus. Small sections of the superficial layer (epidermis) of the patient’s normal skin are removed and then allowed to grow in the laboratory. Once they have grown sufficiently large they can be used as thin grafts to cover an excised nevus.

Drain A tube or wick sometimes inserted during an operation to ensure that any fluid accumulated beneath the skin is immediately removed. Typically inserted within the wound beneath undermined areas or a transposed flap.

EEG (electroencephalogram) Amplification, recording, and analysis of the activity of the brain. An EEG is helpful in diagnosing seizures and other convulsive disorders.

EMLA™ (Eutectic Mixture of Local Anesthetics) A cream used to numb the skin before laser treatments.

Excise To cut away or take out surgically.

Flap An area of skin and subcutaneous tissue that can be elevated and moved to an adjacent area.

Gadolinium A dye given in the vein, that is used as a contrast during MRI to help diagnose mass lesions in patients with NCM.

Hair There are two types of hair:

  • Vellus soft, colorless hair
  • Terminal thick, coarse, colored hair

Hereditary A condition that may be transmitted from one generation to the next.

Hydrocephalus Enlargement of the brain ventricles because of increased fluid. Nevus cells inside the central nervous system blocking the circulation of fluid can be the cause.

Incision A surgical cut.

MRI (Magnetic Resonance Imaging) A diagnostic tool useful for examining the central nervous system.

Malignant An uncontrolled growth of cells that can spread throughout the body.

Melanin The pigment particles that give color to hair, skin and eyes.

Melanocyte A cell that produces melanin.

Melanoma A tumor or mole that is malignant.

Melanosis Proliferations of melanocytes usually resulting in dark pigmentation.

Meninges The three membranes that envelope the brain and spinal cord, called the dura mater, arachnoid and pia mater. The inner two layers are called the leptomeninges.

Mole A collection of pigmented cells in the skin.

Neurocutaneous Existing on both the skin and nervous system.

Nevi Plural of nevus.

Nevomelanocyte Cells composing nevi or moles.

Naevus See nevus.

Nevus A mole or pigmented birthmark.

Papilledema Swelling of the optic disk caused by increased pressure within the brain.

Pigment Any organic coloring matter.

Posterior Axial Along or covering the spine.

Seizure Any sudden and recurring abnormal functioning of the brain. In order of severity, seizures can be classified as:

  • Focal Confined to one part of the body. These can generalize and become grand mal seizures.
  • Petit Mal Brief absences, no muscle spasms
  • Grand Mal (also called clonic-tonic) Unconscious muscle spasms

Serial Excision Having several surgeries done over time to remove a large congenital nevus.


An illustration showing the components of human skin.

  • Epidermis Upper protective layer of skin
  • Dermis “Working” layer of skin, contains hair follicles and other skin structures
  • Subcutaneous Fat (adipose tissue) Thin layer of padding, sometimes not found under “nevus skin.”

Skin Graft Using healthy skin from one area of the body and to cover a part that has lost its skin. This may be full thickness (including all of the dermis) or split/partial thickness (including only part of the dermis).

Simple Excision A single surgical removal.

Tissue (Skin) Expansion Expandable bags are placed under the uninvolved skin and slowly inflated with saline. This causes more uninvolved skin to be created and this extra skin can be used to replace part of a nevus removed during a surgical excision, allowing more nevus to be removed.

V-P Shunt (Ventricular-Peritoneal Shunt) Tube connecting the ventricles of the brain to the abdominal cavity. A passage connecting two anatomical channels and diverting blood or other fluid from one to the other.

Frequently Asked Questions

Child with a nevus at the Nevus Outreach Conference


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