A mole that is changing: what to look for and when to get it checked

Moles are collections of pigment cells. They change slowly with age, sun exposure and hormones, and most changes are benign. Melanoma, a cancer of these cells, can develop in an existing mole or as a new lesion, which is why change is the single most important warning sign.

• Normal mole evolution: gradual raising or lightening of a mole with age, or darkening during pregnancy and sun exposure.

• Benign changes from rubbing, injury, folliculitis or inflammation.

• Atypical (dysplastic) naevi: larger, irregular moles that carry a higher risk and may need monitoring or removal.

• Seborrhoeic keratoses, which are waxy, stuck-on growths that can resemble moles.

• Blue naevi and benign haemangiomas, which can appear dark or reddish.

• Basal cell carcinoma, which may look like a pearly or ulcerating lesion.

• Squamous cell carcinoma and actinic keratosis, with scaly or crusting growths.

• Melanoma: an irregular, changing, multi-coloured lesion, possibly itching, bleeding or crusting.

Asymmetry, jagged borders, several colours (black, brown, red, white, blue), a diameter over 6 mm, a mole that is growing or raised, bleeding, crusting, ulceration, itching, a new dark streak under a nail, a persistent sore that does not heal, and being a different "ugly duckling" lesion are warning signs.

• Urgent GP appointment: any mole with suspicious features or change, so that an urgent skin cancer referral can be made.

• Same-day GP: a mole that is bleeding heavily or ulcerating.

• GP within days to weeks: a new mole in an adult, or a mole that has changed over recent months.

• Routine: stable moles you simply want checked; consider mole mapping if you have many.

The doctor asks how long the mole has been there, how it has changed, itching or bleeding, sun exposure, sunburns, sunbed use, personal and family history of melanoma, number of moles and skin type. They examine the lesion with a dermatoscope and check other moles, lymph nodes and skin.

• Dermoscopy: a magnified examination that helps tell benign from suspicious lesions.

• Excision biopsy: removal of the whole lesion with a small margin for pathology, the standard for suspected melanoma.

• Sentinel lymph node biopsy or imaging: considered for melanomas of certain thickness.

• Total body photography or mole mapping: to monitor multiple or atypical moles.

• Genetic counselling for strong family history.

Check your skin monthly, including back, scalp, soles and between toes, using a mirror or asking someone to help, and photograph moles to track change. Use shade, clothing and SPF 30 or higher sunscreen, and avoid sunburn and sunbeds. Do not try to remove a mole yourself.

The NHS route is a GP and urgent dermatology under the suspected skin cancer pathway. Private dermatology and mole mapping clinics offer direct access to dermoscopy and excision.