melanoma (malignant melanoma)
a highly malignant tumour of melanin-forming cells, the melanocytes. Such tumours usually occur in the skin (pale skin, genetic predisposition, and excessive exposure to sunlight, particularly repeated sunburn, are the most important factors); it may arise from a pre-existing mole or naevus or from apparently normal skin. It can rarely occur at other sites than the skin. Melanomas are usually dark, but may also be free of pigment (amelanotic melanomas). Spread of this cancer to other parts of the body, especially to the lymph nodes and liver, is common if the original melanoma is thick. The prognosis is inversely related to the thickness of the tumour; almost all patients with tumours less than 0.76 mm survive following surgical excision. The mainstay of treatment is surgery, but melanoma can be responsive to immunotherapy and is currently the subject of investigational treatments using melanoma vaccines; the response rate to conventional chemotherapy is poor. Primary prevention programmes reducing episodes of sunburn are advanced in some parts of the world, such as Australia.
The treatment includes surgical removal of the tumor. If melanoma is found early, while it is still small and thin, and if it is completely removed, then the chance of cure is high. The likelihood that the melanoma will come back or spread depends on how deeply it has gone into the layers of the skin. For melanomas that come back or spread, treatments include chemo- and immunotherapy, or radiation therapy. Five year survival rates in the United States are on average 91%.
Melanoma is less common than other skin cancers. However, it is much more dangerous if it is not found in the early stages. It causes the majority (75%) of deaths related to skin cancer. Globally in 2012 melanoma occurred in 232,000 people and result in 55,000 deaths. Australia and New Zealand have the highest rates of melanoma in the world. It has become more common in the last 20 years in areas that are mostly Caucasian.


SYMPTOMS

Eye melanoma may not cause signs and symptoms. When they do occur, signs and symptoms of eye melanoma can include:

A growing dark spot on the iris
A sensation of flashing lights
A change in the shape of the dark circle (pupil) at the center of your eye
Poor or blurry vision in one eye
Loss of peripheral vision
Sensation of flashes and specs of dust in your vision (floaters)
Diagnosis
Visual diagnosis of melanomas is still the most common method employed by health professionals. Moles that are irregular in color or shape are often treated as candidates of melanoma. To detect melanomas (and increase survival rates), it is recommended to learn what they look like (see 'ABCDE' mnemonic below), to be aware of moles and check for changes (shape, size, color, itching or bleeding) and to show any suspicious moles to a doctor with an interest and skills in skin malignancy.
A popular method for remembering the signs and symptoms of melanoma is the mnemonic 'ABCDE':
Asymmetrical skin lesion.
Border of the lesion is irregular.
Color: melanomas usually have multiple colors.
Diameter: moles greater than 6 mm are more likely to be melanomas than smaller moles.
Enlarging: Enlarging or evolving
A weakness in this system is the diameter. Many melanomas present themselves as lesions smaller than 6 mm in diameter; and all melanomas were malignant on day 1 of growth, which is merely a dot. An astute physician will examine all abnormal moles, including ones less than 6 mm in diameter. Seborrheic keratosis may meet some or all of the ABCD criteria, and can lead to false alarms among laypeople and sometimes even physicians. An experienced doctor can generally distinguish seborrheic keratosis from melanoma upon examination, or with dermatoscopy.
Some advocate the system 'ABCDE', with E for evolution. Certainly moles that change and evolve will be a concern. Alternatively, some refer to E as elevation. Elevation can help identify a melanoma, but lack of elevation does not mean that the lesion is not a melanoma. Most melanomas are detected in the very early stage, or in-situ stage, before they become elevated. By the time elevation is visible, they may have progressed to the more dangerous invasive stage.
Nodular melanomas do not fulfill these criteria, having their own mnemonic, 'EFG':
Elevated: the lesion is raised above the surrounding skin.
Firm: the nodule is solid to the touch.
Growing: the nodule is increasing in size.
A recent and novel method of melanoma detection is the 'ugly duckling sign'. It is simple, easy to teach, and highly effective in detecting melanoma. Simply, correlation of common characteristics of a person's skin lesion is made. Lesions which greatly deviate from the common characteristics are labeled as an 'Ugly Duckling', and further professional exam is required. The 'Little Red Riding Hood' sign suggests that individuals with fair skin and light-colored hair might have difficult-to-diagnose amelanotic melanomas. Extra care and caution should be rendered when examining such individuals, as they might have multiple melanomas and severely dysplastic nevi. A dermatoscope must be used to detect 'ugly ducklings', as many melanomas in these individuals resemble non-melanomas or are considered to be 'wolves in sheep clothing'. These fair-skinned individuals often have lightly pigmented or amelanotic melanomas which will not present easy-to-observe color changes and variation in colors. The borders of these amelanotic melanomas are often indistinct, making visual identification without a dermatoscope very difficult.

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