Melanoma glossary: words you may see in reports and letters

Key points

Medical words can describe cells, a tissue finding, a test, or a treatment category.
A definition explains a word; it does not interpret an individual report.
Similar terms can answer different questions, such as a subtype and a stage.

This page is general information, not medical advice. Your own doctor or care team is the right source for questions about your skin, diagnosis or treatment.

A word in a report may be unfamiliar even when the idea behind it is straightforward. These definitions explain terms used in melanoma information, skin biology, testing, and sun protection. They are arranged alphabetically. Sources appear at each letter’s end. NCI means National Cancer Institute; ACS means American Cancer Society; FDA means U.S. Food and Drug Administration; WHO means World Health Organization.

The pathology report explanation gives context for tissue findings. The skin biopsy page describes tissue sampling, and the types page explains the different melanoma names. The sunscreen and clothing-label page puts protection terms in context. A doctor or care team can explain how any of these words applies to a particular person's care.

A

Acral lentiginous melanoma: A skin melanoma subtype found on palms, soles, and beneath nails. These can include areas not usually exposed to sunlight.
Adjuvant: NCI uses this word for treatment after surgery intended to reduce recurrence. Your care team can explain which, if any, applies to you.
Atypical mole: A mole differing from an ordinary mole in color, border, or surface. Some doctors use this term for a dysplastic nevus.

Definitions draw on Wikipedia's acral melanoma reference, NCI's melanoma summary, NCI's moles reference.

B

Basal cell carcinoma: A skin cancer beginning in basal cells in the epidermis. It differs from melanoma, which begins in pigment-making melanocytes.
Biopsy: Removal of cells or tissue for examination under a microscope. The sample is studied for features of disease, including cancer.
BRAF: A gene associated with the growth-signaling protein BRAF. ACS also describes related MEK proteins when explaining targeted treatment categories.
Breslow thickness: The depth of melanoma cells in skin, measured from the epidermis to the deepest invasion. It differs from a spot’s width.
Broad spectrum: A sunscreen label term for UVA and UVB protection. FDA distinguishes it from SPF, which primarily concerns UVB sunburn protection.

Definitions draw on NCI's prevention summary, NCI's melanoma summary, Wikipedia's depth reference, the U.S. Food and Drug Administration's sunscreen reference, ACS's BRAF and MEK explanation.

C

Checkpoint inhibitor: NCI describes this category as blocking proteins regulating immune responses. Your care team can explain which, if any, applies to you.
Chemotherapy: NCI describes this category as medicines directed at cancer-cell growth and division. Your care team can explain which, if any, applies to you.
Clinical trial: A study testing medical approaches in people. Cancer trials can examine detection, prevention, treatment, or ways of improving quality of life.
Collagen: A structural protein forming fibers in the material around cells. It contributes to the support and strength of connective tissue.

Definitions draw on NCI's checkpoint explanation, NCI's melanoma summary, NCI's trials explanation, Wikipedia's matrix reference, Wikipedia's dermis reference.

D

Dermatologist: A doctor specializing in skin diseases. A dermatologist may examine a concerning spot and take a tissue sample for diagnosis.
Dermatopathologist: A doctor specially trained to examine skin biopsy samples. This work concerns cells and tissue rather than only surface appearance.
Dermatoscopy: Examination with a magnifying instrument and light source, also called dermoscopy. It gives a clinician a closer view of skin features.
Dermis: The layer beneath the epidermis, containing blood vessels, nerves, glands, and connective tissue. Collagen and elastic fibers supply support and flexibility.
Dysplastic nevus: A mole differing from an ordinary mole in color, edge, or surface. It is associated with risk but rarely becomes melanoma.

Definitions draw on the American Cancer Society's tests reference, Wikipedia's dermatoscopy reference, MedlinePlus's skin reference, NCI's moles reference.

E

Elastin: A connective-tissue protein involved in stretching and returning toward the original shape. It is part of the skin’s elastic-fiber network.
Epidermis: The outer skin layer. Cells form near its bottom and replace cells shed from the surface; melanocytes lie in its lower part.
Excision: Removal of tissue by an operation. An excisional biopsy removes an entire abnormal area; an incisional biopsy samples part of it.
Extracellular matrix: The network of material outside and between cells, including structural proteins. It supports cells and contributes to their physical surroundings.

Definitions draw on Wikipedia's elastin reference, NIAMS's skin lesson, the American Cancer Society's tests reference, Wikipedia's matrix reference.

F

Fibroblast: A connective-tissue cell producing matrix material, including collagen and elastic fibers. Fibroblasts contribute to structural support and participate in wound healing.
Financial toxicity: Financial problems associated with medical costs, also called financial distress. NCI describes this burden in people with cancer, including those with insurance.

Definitions draw on Wikipedia's fibroblast reference, NCI's financial-distress summary.

Immunotherapy to in situ

Immunotherapy: NCI describes this cancer-treatment category as involving the immune system. Your care team can explain which, if any, applies to you.
Informed consent: Learning key study facts before deciding whether to participate. The process includes procedures, risks, and potential benefits, rather than only a signature.
In situ: Abnormal cells remaining where they started rather than invading deeper tissue. In melanoma in situ, the cells are confined to the epidermis.

Definitions draw on NCI's melanoma summary, Wikipedia's trials reference, ACS's staging reference.

K

Keratinocyte: The main epidermal cell type, contributing to its barrier. These cells move outward and change, eventually becoming part of material shed from skin.

Definitions draw on Wikipedia's keratinocyte reference.

L

Lentigo maligna melanoma: Melanoma developing from lentigo maligna, with cells invading below the epidermis. It commonly occurs on chronically sun-damaged skin in older people.
Lymphedema: Swelling from an abnormal buildup of lymph fluid. NCI describes disrupted lymph flow after node surgery as a possible cause.
Lymph node: A small organ filtering lymph, the clear fluid in the lymphatic system. Nodes contain immune cells and occur throughout the body.
Lymph node dissection: NCI describes removal of a group of lymph nodes separately from sentinel sampling. Your care team can explain which, if any, applies to you.

Definitions draw on Wikipedia's lentigo maligna reference, NCI's lymph node reference.

M

Margin: An edge of tissue removed during surgery. A pathology report can state whether cancer cells were found at that edge.
Melanin: The pigment giving skin its natural color. NIAMS describes absorption of some harmful sunlight, while explaining that pigment does not provide complete protection.
Melanocyte: A cell producing melanin, the pigment responsible for skin color. Melanocytes occur in the lower epidermis and other tissues, including the eye.
Melanoma: Cancer beginning in pigment-making melanocytes. It can begin in the skin or in other tissues that contain these cells.
Metastasis: Spread of cancer to another body site. The new tumor remains the same cancer type as the tumor where it began.
Mitotic rate: A measure of cells actively dividing in a tissue sample. ACS includes it among features a pathologist may examine in melanoma.
Mucosal melanoma: Melanoma beginning in mucous membranes, the moist linings of certain body passages. Its starting location differs from ordinary external skin.

Definitions draw on NCI's pathology reference, NIAMS's skin lesson, Wikipedia's melanocyte reference, NCI's melanoma summary, the American Cancer Society's tests reference, Wikipedia's mucosal melanoma reference.

N

Neoadjuvant: ACS uses this word for treatment before surgery. Your care team can explain which, if any, applies to you.
Nevus: The medical word for a mole; nevi is the plural. An ordinary mole is a cluster of melanocytes and is not cancer.
Nodular melanoma: A skin subtype often appearing as a raised growth, sometimes without dark pigment. Its growth pattern emphasizes depth rather than only width.

Definitions draw on NCI's moles reference, Wikipedia's nodular melanoma reference, ACS's treatment timing explanation.

O

Oncologist: A doctor trained in cancer diagnosis and care. Medical oncologists work with medicines, radiation oncologists with radiation, and surgical oncologists with operations.

Definitions draw on NCI's cancer-care reference, ACS's care-team description.

P

Pathology report: A document describing tissue and examination findings. It can include a diagnosis, the specimen’s visible appearance, microscopic features, and comments.
Photoaging: Skin changes associated with cumulative sunlight exposure. Research distinguishes them from aging due to time while describing some shared biological pathways.
Primary tumor: The tumor where cancer began. It differs from a metastatic tumor formed when cells from that cancer spread to another site.

Definitions draw on NCI's pathology reference, the skin-aging review, NCI's melanoma summary, NCI's eye melanoma summary.

R

Radiation therapy: NCI describes high-energy radiation directed at cancer cells under this category. Your care team can explain which, if any, applies to you.
Recurrence: Return of cancer after treatment. NCI explains that melanoma can return where it began or in another part of the body.

Definitions draw on NCI's melanoma summary.

S

Sentinel lymph node: The node most likely to receive cancer cells first from a primary tumor. More than one node may have this role.
SPF: Sun protection factor, based on tested exposure needed to cause sunburn. FDA describes primarily UVB protection, rather than hours outdoors.
Squamous cell carcinoma: A skin cancer arising in squamous cells of the epidermis. It is grouped with basal cell carcinoma as nonmelanoma skin cancer.
Stage: A description of cancer’s extent. Melanoma staging combines features of the primary tumor with nearby lymph node and distant-site findings.
Superficial spreading melanoma: A skin subtype often extending across the surface before growing deeper. Superficial describes this pattern, rather than excluding deeper growth.

Definitions draw on NCI's lymph node reference, the U.S. Food and Drug Administration's sunscreen reference, NCI's prevention summary, ACS's staging reference, Wikipedia's superficial spreading reference.

T

Targeted therapy: NCI describes a category targeting proteins involved in cancer-cell growth, division, and spread. Your care team can explain which, if any, applies to you.
TNM: A staging system describing the primary tumor, nearby lymph nodes, and distant metastasis. The categories combine to assign an overall stage.

Definitions draw on NCI's melanoma summary, ACS's staging reference, NCI's targeted therapy explanation.

U

Ulceration: A break in skin over a melanoma, described by ACS as a sore. It is considered with thickness and other staging information.
UPF: Ultraviolet protection factor, concerning how much UVA and UVB passes through fabric. It describes fabric shielding rather than sunscreen on uncovered skin.
Uveal melanoma: Melanoma beginning in the uvea within the eye. NCI describes this layer as including the iris, ciliary body, and choroid.
UV Index: A forecast of expected ultraviolet intensity from sunlight. It concerns environmental conditions rather than air temperature or a skin diagnosis.
UV radiation: Ultraviolet radiation, invisible energy from sunlight and certain artificial sources. WHO describes skin and eye damage associated with excessive exposure.

Definitions draw on ACS's staging reference, the Skin Cancer Foundation's clothing reference, NCI's eye melanoma summary, the U.S. Environmental Protection Agency's UV Index explanation, the World Health Organization's UV explanation.

W

Wide local excision: NCI describes removal of melanoma and surrounding normal tissue under this name. Your care team can explain which, if any, applies to you.

Definitions draw on NCI's melanoma summary.