Melanoma Causes
Melanoma is a very common
skin cancer that concerns solely melanocytes, cells that lie in the skin's epidermis, the middle layer of eye
(iris, retina), in the inner ear (cochlea, stria), the digestive epithelium (tissue that lines the inside of the
large and small intestine), and the meninges. Melanocytes play many
roles in your body, among them pigmentation of skin and hair. Melanoma occurs when, due to certain pathogenic
factors (see risk factors), some of these cells multiply uncontrollably to form a malignancy.
Intense or excessive sun
exposure, especially in childhood, is the main factor responsible for the development of melanoma. This risk is
even higher if you have fair skin. Although people with white skin are more often victims of melanoma, the
cancer can also affect individuals with dark or pigmented skin. In black people, the cancer develops
particularly on the palms (of hands) and soles (of the feet).
Depending on the
characteristic of the cancer, melanoma is divided into many stereotypes; the most common
include:
- Superficial
spreading melanoma (SSM) -
SSM represent about 70% of melanomas; it is the most common form of cutaneous melanoma in the
lighter-skinned populations. Often developed on the sun-exposed skin areas, a mole of superficial spreading melanoma tends to grow horizontally for
several
months or years before taking its vertical extension where the lesion becomes thick and
nodular.
- Nodular
melanoma (NM) – the lesion of
this form of melanoma tends to grow vertically. Due to its rapidity to grow, nodular melanoma is often considered as the most aggressive form of
melanoma. It is
characterized by a small blue-black or flesh colored spotting lump. Nodular melanoma lesions tend to
penetrate
deeper into the skin and
bleed easily.
- Acral lentiginous melanoma -
also known as subungual melanoma,
acral lentiginous melanoma develops mostly on the palms, soles and under the nails. Unlike
many forms of melanoma, acral lentiginous melanoma is more frequent among black and Asian people, and can
develop on any area of the body which may or may not be exposed to sunlight. Acral
melanoma is characterized by brown spot, flesh-colored nodules, which tends to resemble a wart or
spotting tumor.
Melanoma
Incidence
Melanoma Risk Factors
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