Skin Moles

Atypical skin moles do not follow an evolutionary pattern of either persistence with stability or differentiation in the direction of ultimate regression, as seen in common acquired melanocytic skin moles. Rather, atypical skin moles demonstrate a persistent and disordered growth, evident both clinically and histologically. The clinical recognition of atypical skin moles focuses on several characteristics that help distinguish them from common acquired skin moles: shape, border, color, diameter, and topography. Many of these features may also be seen in melanoma, although often to a greater degree.

1- Shape: The shape may be round or oval, like the common acquired mole, although asymmetric notching and/or outgrowth of pseudopodia are usually observed in moles over 3 to 4 mm in diameter.

2- Border: The boundary may be irregular with slightly indiscrete to frankly hazy or fuzzy areas, with traces of pink or brownish pigment spilling into surrounding normal skin.

3- Color: The coloration of atypical skin moles is often variegated, with irregular speckling with tan/brown colors and sometimes including foci of tan/brown/dark brown hues or black pigment. Redness may be seen as a component of atypical skin moles but is not normally seen in common acquired skin moles. This is manifest as a pink background color, the intensity of which may vary from trace to slight to moderate. Sometimes only a focal area of pink or a subtle pink hue at the periphery may be seen. The redness does not blanch readily; the degree of redness varies considerably from mole to mole and from patient to patient.

4- Diameter: atypical skin moles are most easily recognized when larger than 5mm in diameter. The Clark group’s initial description of atypical skin moles in B-K mole syndrome patients had emphasized that they were frequently 5 to 10 mm or larger, and that size was an important clue in identifying atypical skin moles. Large size, however, is not a prerequisite for the diagnosis of atypical skin moles.

5- Topography: The topography within any given atypical mole may include macular and papular components. A minimal elevation to tangential lighting is noted in most of them. The skin surface markings may be showing subtle elevation and coarsening. Scale is only infrequently noted. Erosion is not seen in the nontraumatized atypical mole.

The clinical presentation of patients with atypical skin moles seems as varied as the morphology of individual atypical skin moles. The classical type D-2 phenotype may be first evident with numerous distinctly large, irregular, variegate skin moles, mostly concentrated on the trunk and less numerous on the head, neck, and lower extremities. More commonly, however, atypical skin moles are not strikingly large. From several to a dozen atypical skin moles may be mixed among several to several dozen common acquired skin moles. In patients with a solitary atypical mole, it may be located anywhere.