Malignant melanoma arises from melanocytes in a pigmented area (eg, skin, mucous membranes, eyes, or CNS). With spread, prognosis is poor. Melanomas occur mainly on the skin but also on the mucosa of the oral and genital regions and conjunctiva. Melanomas vary in size, shape, and color (usually pigmented) and in their propensity to invade and metastasize.

Risk factors

• Sun exposure
• Sun burn
• Family and personal history
• Fair skin
• Increased numbers of melanocytic nevi
• Immunosuppression
• Occurrence of lentigo maligna
• Large congenital melanocytic nevus
• Dysplastic nevus syndrome
• Exposure to carcinogens- coal tar, creosote, arsenic and radium
• About 40 to 50% of melanomas develop from pigmented moles
• UV radiation and melanoma- UVA light damages the melanocytes, leading to melanoma. Tanning lamps and beds mainly produce UVA radiation

Symptoms

• A change in an existing mole
• The development of a new, unusual-looking growth on your skin

Unusual moles that may indicate melanoma

• A is for asymmetrical shape- irregular shapes
• B is for irregular border- moles with irregular, notched or scalloped borders
• C is for changes in color- moles with many colors or an uneven distribution of color
• D is for diameter- mole larger than about 1/4 inch (6 millimeters)

Types of malignant melanoma

Superficial spreading melanoma: This type accounts for 2/3 of melanomas, typically asymptomatic

Nodular melanoma:  This type accounts for 10 to 15% of melanomas

Lentigo maligna melanoma:  This type accounts for 5 to 15% of melanomas

Acral-lentiginous melanoma:  This type accounts for only 5 to 10% of melanomas

Diagnosis

Skin biopsy

Staging

• Stage I and II: Localized primary melanoma
• Stage III: Metastasis to regional lymph nodes
• Stage IV: Distant metastatic disease

Skin cancer screening

Older than 40, or more often if you're at high risk of developing skin cancer screening head-to-toe inspection of the skin by a dermatologist every year

Prevention

Avoid the sun between 10 a.m. and 4 p.m. Because the sun's rays are strongest during this period

Choose a broad-spectrum sunscreen that has a sun protection factor (SPF) of at least 15, sunscreens block UVB rays very well, most don't block all UVA rays, apply sunscreen 20 to 30 minutes before sun exposure and reapply it every two hours throughout the day

Wear protective clothing and sun glasses

Prognosis

Melanomas may spread rapidly; causing death within months of its recognition, yet the 5-yr cure rate of early, very superficial lesions is nearly 100%. Thus, cure depends on early diagnosis and early treatment

Once melanoma has metastasized to the lymph nodes, 5-yr survival ranges from 25 to 70 % depending on the degree of ulceration and number of nodes involved

Once melanoma has metastasized to distant sites, 5-yr survival is about 10%

Treatment

• Surgical excision
• Possibly adjuvant interferon-α
• Sometimes excision, imiquimod

 

Treatment is primarily by surgical excision. Although the width of margins is debated, most experts agree that a 1-cm lateral tumor-free margin is adequate for lesions < 1 mm thick. Thicker lesions may deserve larger margins, more radical surgery, and sentenel lymph node biopsy

For metastasis radiotherapy and chemotherapeutic agents are used

Biological therapy (immunotherapy)- interferon and interleukin-2 are used.