Atypical Skin Moles

The atypical skin mole is a special kind of skin moles, with clinical and histologic features suggestive of an intermediate form between the common acquired skin mole and melanoma. atypical skin moles are important markers for both familial and nonfamilial melanoma. As many as 50% of patients with “sporadic” melanoma have been observed to have atypical skin moles.
The incidence of atypical skin moles in the general population has been estimated to be 1.8% to 10% and possibly as high as 19%. The presence of atypical skin moles has been established as an independent risk factor for melanoma, along with several other cutaneous traits, including red or blonde hair, solar lentigines, skin type 1 or 2, and increased numbers of common acquired skin moles. A clinical study has found the adjusted relative risk of melanoma to be 2 for a single atypical skin mole and 12 for 10 or more atypical skin moles. Another found a relative risk of 1.6 when one to four atypical skin moles were counted and 6.1 for five or more atypical skin moles. The risk ofmelanoma attributable to atypical skin moles may
be further exacerbated by the coexistence of other melanoma risk factors, such as skin type 1 or 2. The increased risk for melanoma is particularly true in the setting of the atypical skin mole syndrome (Dysplastic Nevus Syndrome). Dysplastic Nevus Syndrome encompasses individuals with multiple atypical skin moles arising sporadically or in a setting of a family history of atypical skin moles or melanoma. Dysplastic Nevus Syndrome has been divided into a number of forms. Type A is sporadic dysplastic skin mole without melanoma; type B is familial atypical skin mole without melanoma; type C is sporadic atypical skin mole with a personal history of melanoma; type D-l is familial atypical skin mole with one family member with melanoma; and type D-2 is familial atypical skin mole with two or more family members with melanoma. Meticulous screening of family members may demonstrate that presumptive cases of sporadic Dysplastic Nevus Syndrome are actually familial.
All patients with Dysplastic Nevus Syndrome have an increased risk for developing melanoma, although the magnitude of the risk varies among the Dysplastic Nevus Syndrome types. The relative risk of melanoma is least in patients with Dysplastic Nevus Syndrome types A and B, and has been estimated to be 7 with a cumulative lifetime risk of 6%. The relative risk of melanoma in type D-2 patients may be as high as 1000 or greater compared with the general population. Individuals with Dysplastic Nevus Syndrome also appear to be at an increased risk for multiple primary cutaneous melanomas.One study found a 35.5% cumulative 10-year risk of developing a secondmelanoma in those with Dysplastic Nevus Syndrome and a history of melanoma as compared with a 17% 10-year risk of developing a second melanoma in those with a history of melanoma butwithoutDysplastic Nevus Syndrome . Patients with Dysplastic Nevus Syndrome may also be at increased risk of conjunctival and intraocular melanoma. The recognition of Dysplastic Nevus Syndrome may allow early detection of melanoma and identi?cation of those at risk and provide the opportunity for the initiation of preventive measures.
A great deal of discussion has centered on the validity of the atypical skin mole as a distinct entity and its potential for progression to melanoma. Much disagreement over its nature stems from a lack of uniform clinical and histologic criteria to define it. In fact, even the term atypical skin mole has contributed to the controversy. Strictly speaking, the term atypical is a histologic one. The purist may object to the clinical description of a melanocytic skin mole as “atypical-looking". atypical skin moles generally demonstrate both clinical and histologic evidence of distorted and disordered architecture. A
statement by the National Institutes of Health (NIH) Consensus Conference in 1992 sought to eliminate the variability in nomenclature and recommended that the term dysplastic nevus be replaced with atypical mole and the histologic diagnosis be termed nevi with architectural disorder along with a description of the degree of melanocytic atypia. A 2004 survey revealed that the term dysplastic nevus remains commonplace.