The ABCDEs of melanoma: what to look for

A spot showing one feature is not automatically cancer, and a melanoma may not show every feature. The guide is a prompt to arrange an examination rather than a home diagnostic test.

A is asymmetry: one half does not resemble the other. B is border: an edge may look ragged, blurred, notched or poorly defined. C is colour: shades or tones vary within the same spot. D is diameter: a spot may be getting wider, although melanoma can also be small. E is evolving: the spot changes in size, shape, colour or feel, or looks unlike your other marks. Evolution is especially useful because it compares the spot with its earlier appearance and with the rest of your skin.

Look over skin that is easy to miss, including the scalp, back, palms, soles, between the toes and around the nails. Use a mirror or ask someone you trust to help with areas you cannot see clearly. In good light, photograph the spot beside a familiar reference and note its location and the date. Do not cut, burn or treat it with a mole-removal product, because irritation can obscure the appearance and delay proper assessment.

Book a prompt appointment with a dermatologist or primary-care clinician for a new or changing spot, an ABCDE feature, or a mark that stands out from your others. Seek assessment sooner if it is rapidly changing, repeatedly bleeding, crusting, painful, persistently itchy or failing to heal. These changes can have causes other than melanoma, but they deserve direct examination. A clinician may inspect the area with magnification and decide whether a biopsy is needed; appearance alone cannot confirm the diagnosis.

Ask whether the spot should be photographed, monitored or biopsied; what specific change should bring you back sooner; and how to check difficult-to-see areas. Mention when you first noticed it, how it has changed, any bleeding or itching, previous skin cancers, and close relatives with melanoma. Bring earlier photographs if available because they can show evolution that is not obvious during a single visit.