For patients

Skin cancer glossary

67 terms you may hear in the exam room or read on a pathology report, in plain language.

A

ABCDE rule

A memory aid for melanoma warning signs: asymmetry, border, color, diameter, and evolving.

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Acral lentiginous melanoma

A type of melanoma that grows on the palms, the soles, or under the nails. It is the most common type in people with darker skin.

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Actinic keratosis

A rough, scaly spot caused by years of sun exposure. It is a precancer, and a small share turn into squamous cell carcinoma.

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Adjuvant therapy

Treatment given after surgery to lower the chance that the cancer comes back.

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Amelanotic melanoma

A melanoma with little or no pigment. It looks pink, red, or skin colored instead of brown or black.

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Atypical mole

A benign mole that looks unusual to the eye or under the microscope. Also called a dysplastic nevus. Having several signals a higher lifetime risk of melanoma.

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B

Basal cell carcinoma

The most common skin cancer. It grows slowly and almost never spreads, but it can damage nearby tissue if left alone.

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Benign

Not cancer. A benign growth does not invade nearby tissue or spread.

Biopsy

Removal of a piece of tissue so a pathologist can examine it under a microscope. It is the only way to confirm skin cancer.

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BRAF mutation

A change in the BRAF gene found in about half of skin melanomas. Tumors that carry it can be treated with BRAF and MEK inhibitor pills.

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Breslow depth

The thickness of a melanoma in millimeters, measured by a pathologist under the microscope. It is one of the strongest predictors of outcome for early melanoma.

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Broad spectrum

A sunscreen label that means the product protects against both UVA and UVB rays.

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C

Checkpoint inhibitor

An immunotherapy drug that blocks a natural brake on immune cells so they can attack cancer. Examples are pembrolizumab, nivolumab, and ipilimumab.

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Clark level

An older way of describing how deep a melanoma has grown, using the layers of the skin. Breslow depth has replaced it in staging.

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Clinical trial

A research study that tests a treatment in people under a written plan called a protocol.

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Completion lymph node dissection

Surgery to remove the remaining lymph nodes in an area after cancer is found in a sentinel node. It is done far less often since the MSLT-II trial.

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Cryotherapy

Freezing a growth with liquid nitrogen. Dermatologists use it most for actinic keratoses.

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Curettage and electrodesiccation

Scraping away a small skin cancer with a sharp ring-shaped tool, then treating the base with an electric needle.

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D

Dermatologist

A physician who specializes in diseases of the skin, hair, and nails.

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Dermatopathologist

A physician, trained in dermatology or pathology, with extra fellowship training in diagnosing skin disease under the microscope. This doctor writes the biopsy report.

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Dermis

The thicker layer of skin under the epidermis. It holds blood vessels, lymph vessels, nerves, and hair follicles.

Dermoscopy

Examination of a skin spot with a dermatoscope, a handheld magnifier with a polarized or immersion light.

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E

Epidermis

The thin top layer of the skin. Basal cells, squamous cells, and melanocytes all live here.

Excision

Cutting out a growth along with a margin of normal skin, then closing the wound with stitches.

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H

Hedgehog pathway inhibitor

A pill, vismodegib or sonidegib, that blocks the growth signal driving advanced basal cell carcinoma.

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I

Immunotherapy

Treatment that helps the immune system find and attack cancer cells.

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In situ

Latin for in place. Cancer cells are confined to the top layer of the skin and have not grown deeper.

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In-transit metastasis

Melanoma deposits in the skin or lymph channels between the original tumor and the nearest lymph nodes.

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Invasive

Cancer that has grown past the layer where it started into deeper tissue.

L

Lentigo maligna

A slow-growing melanoma in situ on sun-damaged skin, usually on the face of an older adult.

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Lymph node

A small bean-shaped organ that filters lymph fluid. Melanoma cells that leave the skin usually travel to the nearest lymph nodes first.

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Lymphedema

Swelling of an arm or leg caused by a buildup of lymph fluid, sometimes after lymph node surgery.

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M

Malignant

Cancerous. A malignant tumor can invade nearby tissue and may spread.

Margin

The rim of normal-looking tissue removed around a tumor. A clear or negative margin means no cancer cells were seen at the cut edge.

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MEK inhibitor

A targeted drug paired with a BRAF inhibitor to treat melanomas that carry a BRAF mutation.

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Melanocyte

The cell that makes melanin, the pigment in skin, hair, and eyes. Melanoma starts in melanocytes.

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Melanoma

A cancer of melanocytes. It is the skin cancer most likely to spread and is usually curable when found early.

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Merkel cell carcinoma

A rare, fast-growing skin cancer that usually appears as a firm, painless, red or purple bump on sun-exposed skin.

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Metastasis

Spread of cancer from where it started to another part of the body.

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Microsatellites

Tiny deposits of melanoma near the main tumor that can be seen only under the microscope. Finding them raises the stage to III.

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Mitotic rate

The number of dividing cells a pathologist counts per square millimeter of tumor. A higher count points to faster growth.

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Mohs surgery

Surgery that removes a skin cancer one thin layer at a time, checking each layer under a microscope until no cancer remains.

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Mucosal melanoma

Melanoma that starts in the moist lining of the nose, mouth, anus, or genitals. It is rare and unrelated to sun exposure.

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N

Neoadjuvant therapy

Treatment given before surgery, often to shrink the tumor and prime the immune system.

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Nevus

The medical word for a mole. The plural is nevi.

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Nodular melanoma

A melanoma that grows downward early. It often appears as a firm, raised bump that keeps growing.

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O

Oncologist

A physician who treats cancer. Medical oncologists give drug treatment, surgical oncologists operate, and radiation oncologists give radiation.

P

Pathology report

The written result of a biopsy or surgery, prepared by a pathologist. It states the diagnosis and the findings that guide treatment.

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Perineural invasion

Cancer cells tracking along a nerve. It raises the risk of recurrence and can change the treatment plan.

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Photodynamic therapy

Treatment that pairs a light-sensitizing drug with a light source to destroy precancerous cells.

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Photosensitivity

An exaggerated skin reaction to sunlight, often triggered by a medicine.

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Prognosis

The expected course of a disease, usually expressed as the chance of recurrence or survival for a group of similar patients.

R

Recurrence

Cancer that comes back after treatment, at the original site, in nearby lymph nodes, or in a distant organ.

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S

Sentinel lymph node biopsy

A procedure that finds and removes the first lymph node draining the area of a melanoma so a pathologist can check it for cancer cells.

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SPF

Sun protection factor. It measures how well a sunscreen protects against UVB, the rays that cause most sunburn. SPF 30 filters about 97% of UVB.

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Squamous cell carcinoma

The second most common skin cancer. Most are cured with a simple procedure, and a small share spread.

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Stage

A label from 0 to IV that describes how far a cancer has grown or spread at diagnosis. Stage guides treatment.

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Superficial spreading melanoma

The most common type of melanoma. It tends to spread across the skin surface before growing deeper.

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T

Targeted therapy

Drugs that block a specific molecule the cancer depends on, such as a mutated BRAF protein.

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TIL therapy

Tumor-infiltrating lymphocyte therapy. Immune cells are taken from a patient's tumor, grown in a lab, and returned by infusion.

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Tumor-infiltrating lymphocytes

Immune cells found among the tumor cells. Pathology reports grade them as absent, non-brisk, or brisk.

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U

Ulceration

Breakdown of the skin over a melanoma, seen under the microscope. It moves the tumor into a higher-risk category at the same thickness.

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UPF

Ultraviolet protection factor, the rating for clothing. UPF 50 fabric lets about 1/50th of UV through.

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UV index

A daily forecast, on a scale from 0 to 11 and higher, of how strong the sun's ultraviolet radiation will be.

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UVA and UVB

The 2 kinds of ultraviolet light that reach the ground. UVB causes most sunburn. UVA penetrates deeper and passes through window glass. Both damage DNA.

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Uveal melanoma

Melanoma of the middle layer of the eye. It is the most common cancer that starts inside the eye in adults, and it differs genetically from skin melanoma.

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W

Wide local excision

The standard operation for melanoma. The surgeon removes the biopsy site with a margin of normal skin whose width depends on tumor thickness.

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The information provided on this website is not intended to serve as a replacement for the advice, diagnosis, or treatment provided by a qualified medical professional. If you have any questions about a medical condition, you should never hesitate to consult with either your primary care physician or another qualified healthcare provider. You should never disregard the advice of a qualified medical professional or put off getting treatment because of something you have read on this website.
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