CMN and Nevus Terms Glossary
This guide was designed to help you understand the terminology you may encounter with regard to large/giant congenital melanocytic 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
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.
Leptomeninges
The inner two layers of membranes that cover the brain and spinal cord. The two layers are the arachnoid and pia mater.
MRI (Magnetic Resonance Imaging)
A diagnostic tool useful for examining the central nervous system including the brain and spinal cord.
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
Abnormal deposits of melanocytes usually resulting in dark pigmentation.
Melanocytosis
The presence of an excessive number of melanocytes.
Meninges
The three membranes that surround 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.
Naevus
See nevus.
Neurocutaneous
Affecting both the skin and nerves.
Nevi
Plural of nevus.
Nevomelanocyte
Cells composing nevi or moles.
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 of awareness, no muscle spasms
Grand Mal (also called clonic-tonic)
Unconscious muscle spasms, loss of consciousness.
Serial Excision
Having several surgeries done over time to remove a large congenital melanocytic nevus.
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 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.