Types of Melanoma

Congenital Nevus
May be giant or small, and may be present at birth or shortly after birth. May occur anywhere on body. Giant congenital nevus is rare occurring in about 1 of 20,000 births with a lifetime risk of malignant transformation of 2-40%. Small congenital nevus occurs in 1 of 100 births and lifetime risk of malignant transformation is not known.
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Lentigo Maligna (Hutchinsons Freckle)
Flat pigmented lesion which gradually enlarges, light tan to dark brown or black with irregular notched borders. Usually located on the face, neck, or arms of the elderly. Begins as MM in-situ and may take 5 to 50 years to become invasive. Usually occurs in 7th decade, accounts for 5% of MM, 3 times more common in females.
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Superficial Spreading Malignant Melanoma
Slightly raised lesion with an irregular border and variable, unevenly distributed pigmentation with shades of red, blue, brown, purple, and black. May be found anywhere on the body but usually on the upper back of men and women and the lower extremities of females. Most common of MM’s(about 70-75%). With early diagnosis, the 5-year survival rate approaches 95%. Long phase of horizontal growth prior to vertical growth and metastasis. Usually occurs in 5th decade, and is equally common in men and women.
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Acral Lentiginous Malignant Melanoma
Initially the lesion is flat with irregular margins and pigmentation, the lesion rapidly becomes raised and nodular. Soles, palms of hands, nailbeds, and oral mucosa are usual locations. Early vertical growth and rapid metastasis. May occur in Asian and African Americans, and accounts for 5-10% of MMs.
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Nodular Malignant Melanoma
Lesion is raised, nodular and sometimes ulcerated. Borders are irregular and color variegated. Occasionally the tumor has no apparent visible pigmentation (amelanotic MM). May occur on any part of the body, but most commonly on legs and trunk. Does not seem to have a horizontal growth phase, usually grows vertically quickly with metastasis. It is twice as common in men and usually occurs in the 5th decade.
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