The acquired nevi and the innate giant naevi are two particular forms which can be considered as precursors of mélanoma.

The melanoma is a cutaneous tumor, preview of which is variable according to the shape and the degree of infringement, but which remains considered as "the most grave" of the cutaneous tumors.

The frequency is in constant increase and doubles about all the decades. More frequently met (5000 new cases a year in France) in the feminine population (3 women for 2 people), the average age of arisen is about fifty. It is very rare during childhood, except in case of preexistant giant naevus.

There is a disparity of arisen according to the race. The existence of a phototype of skin clear, sensitive to the blows of sun, of a red hair and numerous tasks of redness constitute risk factors. The existence of direct familair antecedents multiplies the risk of arisen. The " syndrome of dysplasic nevi" is a clinical entity where the risk of hereditary melanoma is very important.

The Ultraviolet sunbeams B ( UVB) are one of the direct causes of arisen of melanoma. It exists a link between the number of "sunstrokes" before the age of 15 years and arisen following of a melanoma. Advices of caution of the dermatologists, face to face of exhibition solar energy, are frequent but not listened.

Primary prevention rests on the eviction of sun at the hours of strong sunshine, and on protection by adapted clothes and cosmetics.

Secondary prevention rests on the fast diagnosis of melanoma and so on the regular dermatologic supervision.

It is necessary to distinguish four anatomoclinic entities of melanoma:

  • SSM (Superficial Spreading Melanoma).
  • MNE ( Nodular Melanoma).
  • ML (Lentiginous Melanoma, often developed on Dubreuilh's melanosis).
  • MAL ( Acral Lentiginous Melanoma).

Diagnosis is clinical and the treatment is essentially surgical.

Some signs suggest melanoma, in front of a pigmented cutaneous lesion:

  • Asymetry.
  • Born from a preexisting naevus.
  • Color: diverse and heterogeneous.
  • Diameter upper than 5 mms.
  • Edges: irregular as a "geographic card" .

The thickness of the cutaneous infringement, measured on the of excised skin is an important predictive factor, and determines the lateral margins of the future surgical excision (surgical safety excision).

The chemotherapy is an element of the treatment in case of metastases. Gene therapy and immunotherapy constitute potential ways of treatment; but are for the moment, under experimentation.

Some giant naevi can be associated to internal hurts interesting brains, as in neuro-cutaneous melanosis. This very rare, but very grave, disease begins mostly before the age of 2 years by different neurological disorders, such as a hydrocephalus (with too important increase of the cranial perimeter), or seizures. A neuropediatric supervision and medical treatment are necessary.

Internal melanic disorders are mostly impossible to remove surgically and their preview is rather dark. An exam by IRM, made in case of neurological abnormality or systematically after 1 year in front of the existence of an important cutaneous infringement, allows to make the diagnosis of neuro - cutaneous melanosis. A spinal puncture, finding melanocyts within the cerebrospinal liquid, confirms the conclusions of the IRM.

 

 

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