Malignant melanoma
From open-encyclopedia.com - the free encyclopedia.
Melanoma is a malignant tumour of melanocytes . Melanocytes predominantly occur in the skin but can be found elsewhere, especially the eye. The vast majority of melanomas originate in the skin.
| Contents |
Causes
Epidemiologic studies suggest that exposure to ultraviolet radiation is one of the major contributors to the development of melanoma. Other candidates are mutations in or total loss of tumor suppressor genes.
Important factors in determining risk
- the intensity and duration of solar exposure
- the age at which solar exposure occurs
- degree of skin pigmentation (see skin types)
Exposure during childhood is a more important risk factor than exposure in adulthood. (This is seen in migration studies in Australia where people tend to retain the risk profile of their country of birth if they migrate to Australia as an adult). Fair and red-headed people are at greater risk.
Some other risk factors include the "Dysplastic naevus syndrome", previous history of melanoma, and history of melanoma in the immediate family.
Symptoms
Diagnosis of melanoma requires expert knowledge, as early stages may look identical to harmless moles or not have any color at all. Signs and symptoms of melanoma may include:
- darkly pigmented skin lesion, sometimes with areas of little pigmentation
- irregularly shaped skin lesion
- growth or change in shape
- itching, ulceration or bleeding
- change in color
Types of melanoma
- Superficial spreading malignant melanoma (SSMM)
- Nodular melanoma
- Acral lentiginous melanoma
- Lentigo maligna melanoma
- Amelanotic melanoma
Prognostic factors
Features that affect prognosis are tumor thickness in millimeters (Breslow's depth), depth related to skin structures (Clark's levels), type of melanoma, presence of ulceration, presence of satellite lesions, and presence of regional or distant metastasis.
With regard to tumor thickness at the time of diagnosis: thin melanomas (<0.75mm) have a good prognosis, i.e. they can usually be cured by surgical excision alone; tumors of more than 4 mm thickness at the time of diagnosis are very often metastatic and can show very aggressive growth.
Treatment
Complete surgical excision with adequate margins and assessment for the presence of detectable metastatic disease along with short and long term follow up is standard. In metastatic melanoma chemotherapy (15-20% respond to dacarbazine, also termed DTIC), immunotherapy (with interleukin 2 or interferon) as well as local perfusion are used by different centers. They can occasionally show dramatic success, but the overall success in metastatic melanoma is quite limited. Radiation therapy is often used after surgical resection for patients with locally or regionally advanced melanoma or for patients with unresectable distant metastases. In research setting other therapies, such as gene therapy, may be tested.
de:Malignes Melanom nl:Melanoom
