The first signs of melanoma may appear when a mole’s appearance changes or there is new colored or unusual-looking growth on the skin. Though melanoma usually starts at a mole, it can originate from normal skin too. Moles on the skin appear uniform in shape and color; melanomas will have characteristics that can distinguish them from normal moles. Nodular melanoma may appear as a new lump on the skin, and the affected mole may itch and bleed later.
To detect melanoma, physicians and dermatologists check for the following characteristics that can be remembered by the mnemonic ABCDEF:
- Asymmetry: An irregular-shaped mole
- Border: Moles with irregular borders – scalloped or notched
- Color: Growths with many colors that are distributed unevenly
- Diameter: A size metric, moles greater than a quarter of an inch (6 millimeters) in diameter are suspects
- Evolving: Moles that change over time, grow in size, and change shape and color
Nodular melanomas are checked for the following parameters, remembered by the acronym EFG:
- Elevation: The mole has grown above the skin level
- Firm: It is firm to touch
- Growth: It is constantly growing
Acral lentiginous melanoma shows up as lengthwise streaks on the nails that are colored brown, tan, or black. The fold inside of the nail cuticle called the proximal nail fold will become colored. In addition, areas on the palms and soles will have dark pigmentation. Acral melanoma on the feet is identified by the following:
- Change in sensation like tenderness, itching, or pain
- A sore that does not heal
- Changes in the surface of a mole in the area, which appears as a lump or nodule, itching and bleeding
- Swelling and redness beyond the border of a lesion and pigment spreading outside the border of a lesion
Mucosal melanoma appears as dark blue or brown, or white spots or lumps in the area. Sometimes these spots may be multicolored. They may also start as small nodules and then progress to bleeding lumps and even ulcers.
Nasal obstructions and nose bleeds may occur if the disease has affected the nasal passages, and there may be a loss of the sense of smell. Anal and rectal melanoma will be indicated by pain in the area, bleeding, or constipation. Vaginal melanoma will show up with discharge, bleeding, itching, and discoloration of the vulva.
Uveal or ocular melanoma is characterized by dark spots on the iris, blurred or double vision, and other vision changes, changes in the shape and size of the pupils, and a change in the position of the eyeball in the socket.
Amelanotic melanomas are not pigmented, but the spots or nodules can be assessed using the ABCDE test.
Causes
Melanoma is caused by certain factors like DNA damage to the cells that are exposed to ultraviolet radiation, mainly from the sun. Doctors believe that exposure to the sun, sun lamps, and tanning tables are the most likely causes of melanoma. Like other forms of cancers, a weakened immune system will permit cancerous cells to multiply and grow without restraint.
Risk factors
Numerous factors support the origin and growth of melanoma:
- Age
- People with fair skin, blond or red hair, light-colored eyes, or freckles
- People who have severe sunburn
- An unusual number of moles, greater than 50, on the body
- Large brown skin marks present at birth, which are also called birthmarks
- Hereditary causes and the history of family members with melanoma
- Xeroderma pigmentosum is a genetic disorder that disables the skin cells from repairing damaged DNA
