A dysplastic (atypical) nevus is a mole with irregular features that look partly like melanoma but is benign or only mildly abnormal under the microscope. Having many atypical moles, especially with a family history of melanoma, raises the lifetime risk of melanoma.
Key symptoms
- Larger mole, often more than 5 mm across
- Uneven color or a blurred border
- Usually no symptoms
- Many moles, often on the back
What you find on exam
- Full skin exam, including the scalp, between the toes and the soles
- ABCDE rule: asymmetry, border, color, diameter, evolution
- Ugly duckling sign: a mole that looks different from the patient's other moles
- Dermoscopy and photographs to track changes over time
Tests
- Excisional biopsy with narrow margins if melanoma is suspected
- Pathology grades the atypia as mild, moderate or severe
- Total body photography for patients with many atypical moles
Treatment basics
- No treatment for stable lesions; regular skin checks
- Re-excision for severe atypia or positive biopsy margins
- Strict sun protection and no tanning beds
- Teach monthly skin self-exams; screen family members if there is a melanoma history
Red flags
- A changing mole: growing, new colors, raised or itching
- Bleeding, crusting or ulceration
- An ugly duckling lesion, or a new atypical mole in an adult over 40
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Sources: NCCPA PANCE Content Blueprint; NBOME COMLEX-USA clinical presentations; AAMC Core Entrustable Professional Activities (Core EPAs). Written by Making Synapses. Making Synapses is not affiliated with these organizations.