Dermoscopy explained: how a dermatoscope helps assess moles

Normal skin reflects light from the surface, which hides structures below. A dermatoscope uses either a liquid interface or polarised light to cut surface glare, allowing the clinician to see pigment networks, dots, globules, streaks, blue-white areas and blood vessel patterns. These features are scored or pattern-matched to decide whether a lesion looks benign, indeterminate or suspicious.

• Regular versus irregular pigment networks.

• Symmetry of colour and structure.

• Presence of blue-grey areas, regression structures or atypical vessels.

• Streaks or globules at the edge.

• Patterns typical of benign lesions, such as seborrhoeic keratoses or haemangiomas.

• Patterns associated with basal cell carcinoma, such as arborising vessels.

Studies show that dermoscopy, in trained hands, improves sensitivity for melanoma compared with the naked eye and reduces the number of benign lesions removed unnecessarily. NICE guidance on suspected cancer encourages the use of dermoscopy by healthcare professionals who have been trained to use it. Without training, benefit is lost, which is why asking about experience is reasonable.

Images can be stored and compared over time. Sequential digital dermoscopy is used for people with many moles or high risk, to detect subtle change. A lesion that stays the same over months is more likely to be benign, while change warrants action. This approach depends on consistent image quality and follow-up appointments, which should be arranged at the start.

Some melanomas lack typical features, particularly small, amelanotic or fast-growing nodular lesions. Dermoscopy cannot replace histology when doubt remains. It may also be less informative on palms, soles, nails and mucosal surfaces, where patterns differ. Software and artificial intelligence tools that analyse dermoscopic images are developing, but they should be used as aids to a clinician, not as stand-alone verdicts.

Ask whether the clinician has formal dermoscopy training, whether images will be stored with your consent and how they will be compared at review. Ask what the plan is if a lesion is borderline. Ask how your images will be kept secure and for how long.

For most people dermoscopy is quick and unremarkable. The clinician may apply a drop of gel or alcohol to the skin and press the device lightly against the lesion for a few seconds. You may hear the click of a camera if images are stored. Hair may need to be moved aside for scalp lesions. If something looks concerning, the clinician will explain what they have seen and what happens next, such as a biopsy or referral. You can ask to see the image on screen.