Kavitha K. Reddy, MD
Director of Dermatologic Surgery
Department of Dermatology
Boston University School of Medicine
Gary S. Rogers, MD
Professor of Dermatology
Beverly Hospital Cancer Center
Lahey Health System
Atypical moles, also called dysplastic nevi (DN), are considered by many to reside in the grey portion of the spectrum between benign nevi and melanoma. Because of the difficulty of assessing the behavior of an individual DN, and the association with an increased overall risk of melanoma, physicians and patients have grappled with the choice between observation and surgical excision.1 In the absence of a reliable predictive test or formal management guidelines, many physicians elect complete surgical excision of DN. The prevalence of DN is believed to be at least 8-10 percent in susceptible populations,2,3 posing a large health burden. An improved understanding of their role in and relationship with melanoma thus remains an important objective.
Diagnosis and Current Practices
Clinically, atypical moles exhibit border or color irregularity, have a variable and often larger size than ordinary moles (5-15 mm), and are often found in patients with numerous nevi (often >50-100).4 Clark, Lynch and Elder originally described the clinical and histologic characteristics of these distinctive-appearing nevi in a portion of melanoma-prone families and sporadically in individuals prone to melanoma.5,6 Biopsy of either normal-appearing nevi or clinically atypical nevi reveals a subset with histologic features of atypia, such as atypical melanocytic hyperplasia, lamellar or eosinophilic fibrosis, and lymphocytic inflammatory response; these are termed nevi with architectural disorder, or dysplastic nevi.4 Some prefer to name these Clark’s nevi, noting that the term “dysplastic” may imply that all DN have significant malignant potential.7 Unifying diagnostic criteria have not been established to date for atypical or dysplastic nevi, but a number of groups have suggested criteria.4,8
Surgical Excision after Biopsy
In our study of 580 dysplastic nevi and 216 primary cutaneous melanomas, biopsied DN demonstrated a number of key characteristics (Figure 1).1 Positive histologic margins were more frequently reported as the grade of DN increased. In addition, biopsied DN with a positive histologic margin were treated with subsequent complete excision more frequently as the grade of DN increased.1 Changes in diagnosis upon excision of biopsied DN and rates of associated melanoma were examined. Primary cutaneous melanomas were also reviewed and analyzed to determine the type and depth of melanoma, rate of DN-associated melanoma, and grade of associated DN.1
The study outcomes provide evidence suggesting that mildly and moderately dysplastic nevi may generally behave differently than moderately-to-severely and severely dysplastic nevi.1 Of biopsy-diagnosed DN, two were found to harbor melanoma upon re-excision; both were moderately-to-severely dysplastic nevi. A 3.1 percent rate of melanoma was diagnosed on excision of DN with moderate-to-severe dysplasia. In contrast, there was not any instance in the study of a biopsy-diagnosed mildly or moderately dysplastic nevus containing melanoma upon excision.
Of 216 primary melanomas evaluated, a significant association with moderately-to- severely or severely DN was also evident. In cases where a grade of DN was specified, 93 percent of DN-associated melanomas showed moderately-to-severely or severely DN. Mildly and moderately dysplastic nevi were found significantly less often (6 percent of the time when a grade was specified) in DN-associated melanoma.
Investigation of outcomes of the excision of DN represents a milestone in our understanding of DN and raises important questions for discussion.
In advising patients who have a biopsy diagnosis of dysplastic nevus with a positive margin, discussion about the generally benign nature of most DN, relevant concerns and uncertainties about the ultimate behavior of some nevi, especially high-grade DN, and review of treatment choices is encouraged (Figure 2). By explaining the association with an increased overall risk of melanoma at any site, physicians can help moderate excessive fears about a particular individual nevus, while encouraging appropriate monitoring of the entire skin surface for any suspicious or changing lesions and providing education on melanoma-preventive behaviors.
- Reddy KK, Farber MJ, Bhawan J, Geronemus RG, Rogers GS. Atypical (dysplastic) nevi: outcomes of surgical excision and association with melanoma. JAMA Dermatol 2013; 149(8):928-934.
- Piepkorn M, Meyer LJ, Goldgar D, et al. The dysplastic melanocytic nevus: a prevalent lesion that correlates poorly with clinical phenotype. J Am Acad Dermatol 1989; 20(3):407-415.
- Steijlen PM, Bergman W, Hermans J, et al. The efficacy of histopathological criteria required for diagnosing dysplastic naevi. Histopathology 1988; 12(3):289-300.
- Duffy K, Grossman D. The dysplastic nevus: from historical perspective to management in the modern era: part I. Historical, histologic, and clinical aspects. J Am Acad Dermatol 2012; 67(1):1.e1-16; quiz 17-8. doi: 10.1016/j.jaad.2012.02.047.
- Elder DE, Goldman LI, Goldman SC, et al. Dysplastic nevus syndrome: a phenotypic association of sporadic cutaneous melanoma. Cancer 1980; 46(8):1787-1794.
- Clark WH, Jr., Reimer RR, Greene M, et al. Origin of familial malignant melanomas from heritable melanocytic lesions. ‘The B-K mole syndrome’. Arch Dermatol 1978; 114(5):732-738.
- Metcalf JS, Maize JC. Clark’s nevus. Semin Cutan Med Surg 1999; 18(1):43-46.
- NIH Consensus Conference. Diagnosis and treatment of early melanoma. JAMA 1992; 268(10):1314-1319.
- Gandini S, Sera F, Cattaruzza MS, et al. Meta-analysis of risk factors for cutaneous melanoma: I. Common and atypical naevi. Eur J Cancer 2005; 41(1):28-44.
- Tripp JM, Kopf AW, Marghoob AA, Bart RS. Management of dysplastic nevi: a survey of fellows of the American Academy of Dermatology. J Am Acad Dermatol 2002; 46(5):674-682.
- Elston D, McNiff J, Maize J, Sr. Histologically dysplastic nevi that extend to a specimen border. J Am Acad Dermatol 2013; 68(4):682-683.
- Elston D. Practical advice regarding problematic pigmented lesions. J Am Acad Dermatol 2012; 67(1):148-155.
- Bronsnick T, Kazi N, Kirkorian AY, Rao BK. Outcomes of biopsies and excisions of dysplastic acral nevi: a study of 187 lesions. Dermatol Surg 2014; 40(4):455-459.
- Abello-Poblete MV, Correa-Selm LM, Giambrone D, et al. Histologic outcomes of excised moderate and severe dysplastic nevi. Dermatol Surg 2014; 40(1):40-45.
- Tsao H, Bevona C, Goggins W, Quinn T. The transformation rate of moles (melanocytic nevi) into cutaneous melanoma: a population-based estimate. Arch Dermatol 2003; 139(3):282-288.
- Skender-Kalnenas TM, English DR, Heenan PJ. Benign melanocytic lesions: risk markers or precursors of cutaneous melanoma? J Am Acad Dermatol 1995; 33(6):1000-1007.
- Hocker TL, Alikhan A, Comfere NI, Peters MS. Favorable long-term outcomes in patients with histologically dysplastic nevi that approach a specimen border. J Am Acad Dermatol 2013; 68(4):545-551.
- Kmetz EC, Sanders H, Fisher G, et al. The role of observation in the management of atypical nevi. South Med J 2009; 102(1):45-48.
- King R, Hayzen BA, Page RN, et al. Recurrent nevus phenomenon: a clinicopathologic study of 357 cases and histologic comparison with melanoma with regression. Mod Pathol 2009; 22(5):611-617.
- Goodson AG, Florell SR, Boucher KM, Grossman D. Low rates of clinical recurrence after biopsy of benign to moderately dysplastic melanocytic nevi. J Am Acad Dermatol 2010; 62(4):591-596.