melanoma
Meaning of melanoma: Far less common than the everyday skin cancers but responsible for most deaths from them, because it spreads while it is still small.
Definition of melanoma
Melanoma is a cancer that begins in melanocytes, the cells that make the pigment melanin coloring skin, hair and eyes. It arises most often in the skin, either as a new spot or within an existing mole, but melanocytes also sit in the eye, the lining of the nose and mouth, and parts of the digestive tract, where melanoma occurs less commonly.
How melanoma is built
- melan/o Combining form · Greek black, dark
- -oma Suffix · Greek tumour, mass, swelling
A medical term is read from its ending backwards: the suffix first, then the prefix, then the root. See all 223 word parts.
What makes melanoma different from other skin cancers?
Basal cell and squamous cell carcinomas are far more common, grow where they start and rarely travel. Melanoma arises from a cell type that migrates during development, and it can enter lymphatic vessels and the bloodstream while the tumor on the surface is still thin. Depth is therefore the dominant measurement: the thickness of the tumor through the skin, together with whether the surface has broken down and whether nearby lymph nodes are involved, drives staging far more than the width of the visible spot. This is the reason a small lesion is not automatically a minor one.
What are the main forms?
| Form | Where it appears |
|---|---|
| Superficial spreading | The commonest form, growing outward across the skin before growing downward |
| Nodular | A raised lump that grows downward early |
| Lentigo maligna | Slow-growing, on skin with long-term sun exposure |
| Acral lentiginous | Palms, soles and under the nails; not linked to sun exposure |
| Ocular melanoma | Within the eye, most often the pigmented layer beneath the retina |
| Mucosal | Linings of the nose, mouth, genital tract or gut |
The acral and mucosal forms carry particular weight for people with darker skin, in whom melanoma is much less common overall but is proportionally more likely to appear on a palm, a sole or a nail bed than on sun-exposed skin. A dark streak in a nail or a changing patch on the sole is easily overlooked.
What changes prompt evaluation?
Change is the signal rather than appearance alone: a mole that alters in size, shape, color or border, one that itches, bleeds or crusts, or a new pigmented spot that looks unlike the others on the same person. Not every melanoma is dark. An amelanotic melanoma makes little or no melanin and can appear pink or skin-colored, which delays recognition. Diagnosis requires removing the lesion and examining the tissue under a microscope, since no scan or photograph can settle it.
Also known as
Used in a sentence
A biopsy of the changing mole confirmed a diagnosis of melanoma.
Good to know
Melanoma can spread while the visible lesion is still small, and not all melanomas are pigmented, so a pink or skin-colored lesion and a dark streak under a nail can both represent the disease.
Word origin
Where “melanoma” comes from
Formed from melano-, from Greek melas, melanos, meaning black, and -oma, meaning tumor or mass.