Atypical (Dysplastic) Nevi: Unusual Moles Monitored with ABCDE + Dermoscopy
Updated: 1 day ago
Atypical nevi, also called dysplastic nevi, are moles with clinically unusual features. They are typically 5 mm or larger, with irregular borders and uneven, multiple shades of colour. These moles are considered a marker of the risk of developing melanoma, a type of skin cancer. People with 5 or more atypical moles have about a 6-fold higher risk of melanoma, and if there is also a family history of melanoma, they may fall into the FAMMS group (Familial Atypical Multiple Mole Melanoma Syndrome), which is associated with CDKN2A gene mutations. Knowing how to check and monitor your moles properly helps detect any abnormality early.
The ABCDE rule and features of atypical moles
Basic self-checking of moles uses the ABCDE rule, an approach recommended by doctors, as follows.
A: Asymmetry means the mole is not symmetrical; if divided in half, the two sides do not match.
B: Border means the edge is irregular, rough or notched.
C: Color means the colour is uneven, with several shades.
D: Diameter means the width is more than 6 mm.
E: Evolution means there is a change in size, colour or shape.
If one or more of these signs are present, the mole should be examined with a dermoscope, and if three or more are present, a biopsy should be considered. Common clinical features of atypical moles include a fried-egg appearance, with a light brown centre surrounded by darker pigment, and a rough surface texture.
Read more about what a cancerous mole looks like, and which moles are risky.
Monitoring with full body photography and dermoscopy
For people with several atypical moles, systematic monitoring helps detect changes more accurately.
Full body photography: Photographs of the whole skin surface are taken as a baseline for comparison.
Sequential dermoscopy: Suspicious moles are examined with a dermoscope every 6-12 months (more often for high-risk groups).
Warning sign: If a mole changes by 1 mm or more, or a new mole appears, a biopsy should be done promptly.
When should a mole be excised?
Excision is considered based on the biopsy result and the degree of dysplasia.
Mild: Mild dysplasia does not need re-excision if the margins are clear.
Moderate to severe: Moderate to severe dysplasia: re-excision with a 2-5 mm margin is recommended.
Severe: Severe dysplasia: re-excision with a 5 mm margin is recommended, as for melanoma in situ.
Long-term care: Avoid sun exposure, have a full skin examination every 6 months, and consider CDKN2A gene testing if there is a family history.
Frequently asked questions
Do all atypical moles need to be removed? No. Only moles with unusual features are removed. Moles that cause no concern can be followed with sequential dermoscopy.
Does everyone need full-body photography? No. It is needed for people at high risk, such as those with 5 or more atypical moles, the FAMMS group, a history of melanoma, or immunosuppression.
Will a mole come back after it is removed? If it is removed with an adequate margin, it usually does not come back (about 5%), but a recurrent nevus must always be distinguished from melanoma.
Are Thai people at high risk of melanoma? Lower than in fair-skinned people, but acral lentiginous melanoma on the palms, soles and nails is common in Asians, so moles in these areas should be checked with special care.
If you have a mole with an irregular border, uneven colour or any change, it should be examined by a specialist with dermoscopy. We recommend consulting a dermatologist at Siam Dermatology, tel. +66 61 448 7000 or LINE @siamderm
Written by Dr. Patara Voravutinon, Dermatologist · Last reviewed 16 July 2026
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