Recognition of Dysplastic Nevi and Risk of Malignant Melanoma

Dysplastic nevi are important to recognize because of an increased risk for development of malignant melanoma.

Clinical criteria for a dysplastic nevus:

(1) maximum diameter of 5 mm or more (one half unlike the other half)

(2) entirely flat, or having a flat component

(3) at least 2 of the following

(3a) variable pigmentation (color varies from one area to another)

(3b) irregular (scalloped or poorly circumscribed border), asymmetric (one half unlike the other half) outline

(3c) indistinct borders

Type and Number of Nevi	Relative Risk for Developing Melanoma
congenital nevi	no increased risk
increased number of small nevi (2-5 mm), without dysplastic nevi	2-fold
increased number of small and large nevi, without dysplastic nevi	4-fold
one dysplastic nevus	2-fold
10 or more dysplastic nevi	12-fold

Number of Nondysplastic Nevi	Relative Risk for Developing Melanoma
0 - 24 small (2 - 5 mm)	1.0
25 - 49 small (2 - 5 mm)	1.8
50 - 99 small (2 - 5 mm)	3.0
>= 100 small (2 - 5 mm)	3.4
1 large (> 5 mm)	1.0
2 - 4 large (> 5 mm)	1.3
5 - 9 large (> 5 mm)	1.7
>= 10 large (> 5 mm)	2.3

Number of Dysplastic Nevi	Relative Risk for Developing Melanoma
1	2.3
2-4	7.3
5-9	4.9
>= 10	12

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