Remember the ABCDE rule when watching moles

DEAR DOCTOR: Why is melanoma so dangerous? I had a squamous cell growth removed, and it was no big deal. However, a mole that had to be biopsied for melanoma (it turned out to be benign) has my doctor worried.

DEAR READER: We’re glad to hear your biopsy results came back negative for melanoma, and we can understand your doctor’s concern. Melanoma isn’t the most common skin cancer, but it is the most serious. This type of cancer can grow quickly and aggressively spread to other parts of the body. Although melanoma accounts for just 1% of all skin cancer diagnoses, it causes the majority of skin cancer deaths. Early diagnosis and treatment is crucial.

Skin cancer is the most common type of cancer, with about 9,500 new cases diagnosed each day. More people are diagnosed with skin cancer each year in the United States than all other types of cancer combined. Like all cancers, it occurs due to abnormal and uncontrolled cellular growth.

Squamous cell and basal cell carcinomas, the first- and secondmost common types of skin cancer, are named after the types of skin cells from which they arise. They tend to grow slowly, and it is uncommon for them to spread. Melanoma arises from melanocytes, cells that produce a brown pigment called melanin. Researchers have discovered that unlike other cancer cells, which have to “learn” how to spread through the body, melanoma cells are equipped with a cellular mechanism that lets them start spreading immediately. That’s why this cancer is so deadly.

Risk factors for melanoma include a history of sunburn, excessive exposure to UV light, the use of tanning beds, having fair skin, a family history of the disease and having a large number of moles or certain types of unusual moles. Normal moles generally have a consistent color — usually tan or brown — and uniform borders. When moles change shape or color, become irregular, get crusty or bleed or grow larger, or when new moles or skin discolorations appear and change, it can be cause for concern. A mole that looks markedly different from the other moles on your body can also indicate something is wrong. These warning signs have been turned into a memory prompt, the “ABCDE rule”:

— Asymmetry: The halves of a mole or birthmark don’t match.

— Border: Edges are irregular, jagged or blurred.

— Color: Color is irregular or patchy, sometimes with areas of red, pink, white or blue.

— Diameter: Moles larger than 1/4 inch across, although melanomas can be smaller than that.

— Evolving: A mole or birthmark that begins to change shape, color or size.

Studies show that regular sunscreen use can cut melanoma risk in half. Considering that the number of melanoma deaths is expected to increase by 22% in 2019, this bit of self-care can be a life-saver. Note and keep a record of the moles on your body and how they change. If you see any of the ABCDE characteristics, contact your doctor immediately. Eve Glazier, M.D., MBA, is an internist and associate professor of medicine at UCLA Health. Elizabeth Ko, M.D., is an internist and assistant professor of medicine at UCLA Health.