Melanoma Information

What is Melanoma

Melanoma is the most serious form of skin cancer. It begins in the pigment cells (melanocytes, see diagram below) that produce skin color. Most melanomas can be treated successfully if they are detected at an early stage. If melanoma is not detected at an early stage, it can spread to other parts of the body and is potentially a lethal form of cancer.

skin diagram.jpg

Since most pigment cells are in the skin, most melanomas start on the skin. They can occur in the eye and rarely in the membranes of the nasal passages, oral, pharyngeal mucosa, vaginal and anal mucosa.

Most melanomas (70%+) begin in or near an existing mole or dark spot on the skin. It is important that you know the size, color and location of moles on your body so that you can take note of changes in existing moles or the appearance of new moles. Some “birthmarks” (congenital moles) can also develop into melanomas.

Ordinary Moles are evenly colored, have sharply defined edges and are round or oval in shape. They can be flat or raised and are less than 6 millimeters (1/4″) in diameter (about the size of a pencil eraser). Melanomas have an irregular appearance and are usually larger than an ordinary mole.

What Causes Melanoma

Excessive exposure to the ultraviolet radiation of the sun is the most important preventable cause of melanoma. People in southern regions, where the sunlight is more intense, are more likely to develop melanoma than those in northern regions. Melanoma has also been linked to excessive sun exposure in the first 10 to 18 years of life. Other possible causes include genetic factors and immune system deficiencies. 

To read more about specific risk factors for melanoma, go to the risk factors tab or click here.

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.

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.

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.

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.

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.

Information provided courtesy
of Chiron Corporation