Melanoma

Melanoma is a cancer arising from melanocytes, the pigment-producing cells found mainly in skin and also in the eyes and mucous membranes. It can spread to distant organs.

Melanocyte: A pigment-producing cell that makes melanin and transfers it to nearby cells. Melanoma begins when melanocytes acquire changes that allow uncontrolled growth.
Dermoscopy: A skin examination technique using magnification and illumination to reveal structures beneath the skin surface. Dermoscopy helps clinicians assess suspicious pigmented lesions for melanoma features.
Ultraviolet radiation: Electromagnetic radiation with wavelengths shorter than visible light, including UVA and UVB. UV exposure damages DNA in skin cells and is a major preventable melanoma risk.
Basal cell carcinoma: A common skin cancer arising from basal cells of the epidermis, usually growing slowly and rarely metastasizing. Unlike melanoma, it arises from epidermal basal cells and seldom spreads to distant organs.
BRAF: A gene encoding a protein kinase in the RAS–RAF–MEK–ERK cell-signaling pathway. BRAF mutations can keep growth signals active in melanoma cells.
Skin biopsy: The removal of skin tissue for microscopic examination and diagnosis. Biopsy establishes whether a suspicious lesion is melanoma and supplies staging details.
UV signature mutation: A DNA change pattern associated with damage from ultraviolet radiation, especially adjacent pyrimidine substitutions. Many cutaneous melanomas bear mutations consistent with past ultraviolet damage.
Cutaneous squamous cell carcinoma: A skin cancer arising from epidermal keratinocytes that can invade locally and sometimes metastasize. It shares UV-related risks with melanoma but originates in keratinocytes, not melanocytes.
NRAS: A gene encoding a small GTPase that relays signals controlling cell growth and survival. NRAS mutations activate growth signaling in a subset of melanomas.
Breslow depth: The measured thickness of a melanoma from the top of the granular layer to its deepest invasive cell. Breslow depth is a major determinant of primary melanoma stage and prognosis.

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