Malignant melanoma is a tumor of the pigment-producing cells of the skin. Pigment cells are located all over the dermis (skin) and supply the skin's color. Pigment cells are more heavily concentrated in moles. When one of these pigment cells becomes malignant, it produces a tumor called a melanoma. Melanomas can appear anywhere; in parts of the skin which previously looked normal or in moles which have been present for a long time.
Melanoma is frequently called a skin cancer because it derives from the cells of the skin. This definition is not entirely correct, as melanoma differs from typical skin cancer in two respects. Not only is melanoma fairly rare, it may metastasize to other parts of the body, something which typical skin cancers do not normally do. Because of this tendency to spread, patients with melanoma are usually referred to specialists for treatment.
What is usually meant by the term "skin cancer" is a common tumor called a basal cell carcinoma. These types of tumors tend not to spread and are normally cured by simple treatments such as excision (surgery) or cryosurgery (freezing).
While the exact cause is unknown, melanoma occurs more often in people with fair complexions whose skin burns easily. Melanoma is thought to occur more frequently in people who received a number of blistering sunburns in childhood.
Melanoma is not contagious and cannot be transmitted by physical contact. However, either because of their genetic makeup or their inherited skin coloring, the children of melanoma patients tend to have a slightly elevated risk of developing melanoma.
When melanoma spreads, some of its malignant cells invade either the local blood vessels or the lymphatic vessels, which carry lymph fluid to lymph node groups. If malignant cells invade the lymph vessels, their fluid can carry them to the lymph nodes. If malignant cells invade the blood vessels, they may be carried by the blood to distant parts of the body.
When melanoma spreads, the most likely site for it to reappear is in the lymph nodes that are closest to the original tumor site. For example, if the primary melanoma was on the arm, the closest lymph nodes would be in the armpit. If the primary tumor was on the leg, the closest nodes would be the groin; for the head, the adjacent lymph nodes are in the neck. For a primary melanoma on the trunk, the proximate lymph nodes would be the groin or the armpit.
In 2002, a staging system for malignant melanoma was developed.
Stage I: primary melanoma of a certain size without ulceration, no lymph node involvement, and no metastases (secondary tumors.)
Stage II: primary melanomas that are somewhat larger but which also lack ulceration, lymph node involvement, or metastases.
Stage III: metastasis to the lymph nodes, or in-transit metastases/satellites, with no distant metastases.
Stage IV: Distant metastases. Melanomas which progress to this stage are frequently fatal.
With the destruction of the ozone layer, more harmful ultraviolet (UV) rays reach the skin. The daily use of a sun block of at least Sun Protection Factor (SPF) 15 may help to prevent some skin cancers and premature aging of the skin.
It is important for everyone to be aware of their skin and to note any changes such as small pearly bumps, spots that refuse to heal, or changes in moles, and to seek treatment from a medical doctor at the first sign of such changes.
Many skin cancers have a high rate of cure if caught early enough.