Skin CANCER (melanoma)-General
Melanoma is one of the forms of skin cancer. It develops in melanocytes or pigment cells. For ease, we will use the terms skin cancer and melanoma in the singular. But there are different kinds and, even in the case of similar illnesses, each person has specific peculiarities.
Anatomy of the Skin
Our skin consists of three layers. The surface layer bears the epidermis name, the middle layer is called dermis, and the lower layer is referred to as subcutaneous or hypodermis connective tissue.
The epidermis consists mainly of two types of cells: basal cells and pavement cells. In addition, pigment cells are found in the epidermis, the melanocytes. The basal cells of the deep layer of the epidermis are able to divide. The new skin cells are formed at their level. Over a period of one month, these new cells migrate upward and at the same time change shape. At first they are round or oval, then they become more angular and afterwards they flatten (pavement cells).
The dermis is made of connective tissue, also called support tissue. It includes: sweat glands (which produce sweat), hair follicles associated with sebaceous glands, blood and lymphatic vessels, as well as nerve endings.
The Hypodermis mainly serves as a support and consists mainly of greasy tissue.
The skin
The functions of our skin
It protects our organism, for example with regard to infections and ultraviolet (UV) rays.
It allows us to perceive signals from our environment: the cutaneous nerves transmit the painful, sensitive and thermal stimuli to the brain that transforms these stimuli into sensations.
Finally, the skin plays a big role in regulating body temperature, the sweat glands of the skin contributing largely to this regulation.
Some figures
In Belgium, according to the Cancer Registry figures, in 2013, 2635 new cases of skin cancer were recorded. Despite the prevention campaigns, this cancer is in sharp increase.
Before puberty, melanoma is very rare. Thereafter, it may occur at any age, but is proportionately more prevalent before 60 years compared with most other cancers.
Types of melanoma
Melanoma literally means black tumor. This type of skin cancer appears in melanocytes or pigment cells. Normal melanocytes are present in disseminated form throughout the skin. They can also be gathered in small clusters and then form pigmented stains, such as moles (Naevi).
We are talking about melanoma when, at a place in the skin, the pigment cells turn into cancerous cells. The resulting malignant tumor will present itself as a pigmented spot that grows or grows, changes color etc.
Where do melanomas lie?
Melanoma may occur at the level of an existing mole or a pigment cell isolated in a "healthy" skin area with no pre-existing pigment stain. Melanomas can grow at any place in the skin. In women, they appear a little more frequently at the leg level, in men at the trunk level. Areas covered with hair, such as the scalp, can also be reached.
Exceptionally, melanoma may appear in the mucosa of an organ. A mucous membrane is a thin layer of tissue that lines the cavities of the body. These melanomas can affect the mouth, nasal cavity and throat, as well as the vagina and anus. Melanoma sometimes also occurs in the mucous membranes of the eyelids and in the eye itself.
Metastasis of skin cancer
Just like any other cancer, skin cancer can send metastases elsewhere in the body. by lymph, tumor cells reach the lymph nodes of the neck, armpits or groin (depending on the location of the tumor) and multiply to give rise to metaganglion metastasis.
Cancer cells can also be disseminated by blood to other parts of the body, for example to the lungs, liver, other skin site or brain. However, metastases of a melanoma almost always begin to invade the regional lymph nodes, before reaching other organs at a distance by blood.
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