Melanoma is a cancer of the skin or mucous membranes, developed at the expense of melanocytes (melanocytic tumor).
Its head is the original skin in the vast majority of cases. However, there are melanomas of the eye (choroidal melanoma), mucous membranes (mouth, anal canal, vagina), and even more rarely internal organs.
Despite what its name suggests, a melanoma is not always dark. Actinic keratosis favors the development of this cancer. Thus, contrary to popular belief, the nevi are not in the vast majority of cases of precancerous states that turn into cancer from sun exposure and multiple systematic excision of nevi in order to avoid the occurrence of melanomas is useless. In addition, the nevus of the trunk and face (usually areas most exposed to UV) were not more likely to turn into melanoma than other skin areas more protected.
It is acknowledged that large congenital nevi have an increased risk of malignant transformation, and a high number of nevi on the body is a marker of risk of developing melanoma, WITHOUT latter results from the conversion of such nevi.
It first appears as a simple pigmented spot.
The sunburn, especially in childhood, and family history are the main risk factors. The regular, moderate sun exposure of skin to tan may have some protective effect,. Although it can occur anywhere, melanoma tends to form more often on the body parts that are covered in daily life but occasionally exposed during sunbathing, as the torso and legs. Similarly, the use of artificial ultraviolet tanning purposes increases the risk of melanoma with a clear correlation with the dose taken.
There also seems to increase a moderate risk of developing melanoma in patients with history of endometriosis or fibroids of the uterus in women.
The skin color also plays an important role.
Its incidence increases more than 2.
The exceptional capabilities of metastasis of melanoma are due to reactivation during the carcinogenesis of a gene called Slug. This is the gene that allows migration in the embryo cells derived from neural crest, which include melanocytes.
The surface forms are divided into three groups:
The surface forms evolve in two stages:
However, in about 30% of cases, nodular melanoma is immediately, without having gone through a stage surface individualized.
Gross pathology: nodular melanoma is a tumor lesion protruding, monochrome, black or bluish gray pink, sometimes amelanotic, which will be accompanied by an inflammatory halo and ulcerate.
Microscopy: There is a proliferation sheet, without libraries, located in the dermis without epidermal.
Breslow: The prognosis of melanoma depends on the depth extension, it is almost always fatal if the invasion is up to the hypodermis. In practice, we measure the tumor thickness in millimeters (Breslow). A thickness greater than or equal to 0.75 mm is a poor prognosis and is more likely to be associated with lymph node metastases, visceral, liver, lung and brain and increased mortality (25% of cases).
The nodular cutaneous melanoma is recognized by a skin based on the dermis, which contains pilosebaceous annexes. The dermis and hypodermis are invaded by a large nodular lesion. By area, this lesion contains thecal of tumor cells wound on top of each other. On some slides, some libraries are visible at the dermal-epidermal junction. At depth, these tumor cells have a more fusiform. The tumor cells are large with a strong core nucleolated. They sometimes contain black pigment (melanin).
The severity of these tumors, when they came to nodular stage, controls the removal of any suspicious pigmented lesion: lesion extensively shaped notched, uneven coloring, naevus that changes.
The prognosis is determined by the thickness of the primary tumor (Breslow) that is expressed in millimeters measured from the point the most superficial to the deepest point of the tumor, supplemented by the Clark index ranging from 1 to 5 next layer of the skin the deepest reaches of the tumor, and the result of the staging (for metastases). At the initial stage of superficial spreading, the prognosis approaches 100. Safety margins, that is to say the surface of healthy skin to be removed with melanoma depends on its thickness. Until the 1980s, the current margin of excision was approximately 4 to 5 cm around the lesion, causing significant scarring or disfigurement. The safety margin is currently advocated by a few millimeters. Specifically we recommend a 5 mm margin for melanoma Intraepidermal, 1 cm for melanomas with a thickness below 1 mm and 2 cm for melanomas thicker (reduced to 1 cm for locations difficult to operate).
The staging is based primarily on the local thickness (Breslow) and on the presence of micro-ulcerations. The sentinel node biopsy (the one draining the site of melanoma) is also a common procedure in the evaluation of its extension.
Various chemotherapy regimens or immunotherapy may be offered for advanced stages, including interferon therapy, the latter giving mixed results. In metastatic forms, several drugs are being tested, with promising results, including an inhibitor of the kinase encoded by the mutated BRAF gene, the vemurafenib and ipilimumab.
It is based on sun protection (especially children) and consultation of a dermatologist in case of modification of an existing mole or the appearance of a black skin lesion. Sun protection is based on the avoidance or the use of protective sunscreen. The dermatologist uses a dermatoscope to observe the lesions.
It is recommended to be wary especially lesions that are (rule '.
Experimentally, vitamin C associated with the copper would have a toxic effect on melanoma cells that accumulate copper ions,,.
Erythema multiforme Vasculitis