Atypical Nevus

Key Points
A nevus refers to a mole
The term dysplastic nevus is often used interchangeably with “atypical” mole, although many consider the latter to be a clinical term, with “dysplastic nevus” used to describe certain histologic (microscopic) features of the mole
Multiple dysplastic nevi suggest a higher incidence of melanoma, especially if there is a family history of melanoma

Atypical moles often have a characteristic appearance, although individual lesions may not show all the findings. Typically, they are larger than average moles, with many lesions measuring larger than 5-6 millimeters. Borders are usually irregular, notched, or ill-defined. Macular (flat) and papular (raised) areas may be present within a single lesion (also described as a “fried egg” appearance). Color is highly variable and ranges from tan to dark brown to pink.

There is significant debate about whether dysplastic nevi are more likely than ordinary moles to develop into melanoma. There is a reasonably strong consensus, however, that those individuals with multiple dysplastic nevi and a family history of melanoma are at a higher risk for developing melanoma. Such patients should have their moles examined at least yearly. Also, such patients should perform self exams with regularity.

Differential Diagnosis (Other conditions with similar appearance)

Blue Nevus
Seborrheic Keratosis
Dermatofibroma
Spitz Nevus
Lentigo
Malignant Melanoma

Diagnosis
Key Points
An atypical mole is a common diagnosis for a seasoned dermatologist to make clinically; however, a skin biopsy may be recommended to distinguish some dysplastic nevi from melanoma
* Some dermatologists are trained in a technique known as Dermoscopy, which can sometimes increase the clinical sensitivity of the exam

If an atypical mole is identified, a skin biopsy should be strongly considered to rule out early or evolving Melanoma. After removal of the mole, a skin pathologist will make a judgment as to whether the mole is benign, malignant (cancerous), or that it shows enough “dysplasia” to be monitored in order to ensure that it doesn’t develop into a Melanoma.

Treatment

The only treatment is to remove the mole. If the initial biopsy removes the entire mole and there are no features of melanoma, then the area can safely be observed. If severely dysplastic features are identified or if melanoma is suspected by the pathologist, then re-excision of the area is usually recommended. Also, people with dysplastic nevi should certainly avoid tanning beds, excessive sun exposure, and routinely use sunscreen.