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Importance: Little evidence exists to guide the management of moderately dysplastic nevi excisionally biopsied without residual clinical pigmentation but with positive histologic margins (hereafter referred to as moderately dysplastic nevi with positive histologic margins)., Objective: To determine outcomes and risk for the development of subsequent cutaneous melanoma (CM) from moderately dysplastic nevi with positive histologic margins observed for 3 years or more., Design, Setting, and Participants: A multicenter (9 US academic dermatology sites) retrospective cohort study was conducted of patients 18 years or older with moderately dysplastic nevi with positive histologic margins and 3 years or more of follow-up data collected consecutively from January 1, 1990, to August 31, 2014. Records were reviewed for patient demographics, biopsy type, pathologic findings, and development of subsequent CM at the biopsy site or elsewhere on the body. The χ2 test, the Fisher exact test, and analysis of variance were used to assess univariate association for risk of subsequent CMs, in addition to multivariable logistic regression models. To confirm histologic grading, each site submitted 5 random representative slide cases for central dermatopathologic review. Statistical analysis was performed from October 1, 2017, to June 22, 2018., Main Outcomes and Measures: Development of CM at a biopsy site or elsewhere on the body where there were moderately dysplastic nevi with positive histologic margins., Results: A total of 467 moderately dysplastic nevi with positive histologic margins from 438 patients (193 women and 245 men; mean [SD] age, 46.7 [16.1] years) were evaluated. No cases developed into CM at biopsy sites, with a mean (SD) follow-up time of 6.9 (3.4) years. However, 100 patients (22.8%) developed a CM at a separate site. Results of multivariate analyses revealed that history of CM was significantly associated with the risk of development of subsequent CM at a separate site (odds ratio, 11.74; 95% CI, 5.71-24.15; P < .001), as were prior biopsied dysplastic nevi (odds ratio, 2.55; 95% CI, 1.23-5.28; P = .01). The results of a central dermatopathologic review revealed agreement in 35 of 40 cases (87.5%). Three of 40 cases (7.5%) were upgraded in degree of atypia; of these, 1 was interpreted as melanoma in situ. That patient remains without recurrence or evidence of CM after 5 years of follow-up., Conclusions and Relevance: This study suggests that close observation with routine skin surveillance is a reasonable management approach for moderately dysplastic nevi with positive histologic margins. However, having 2 or more biopsied dysplastic nevi (with 1 that is a moderately dysplastic nevus) appears to be associated with increased risk for subsequent CM at a separate site.

Importance: Controversy persists regarding the appropriate management of incompletely excised, biopsy-proven, mild and moderate dysplastic nevi (DN)., Objective: To determine long-term risk of associated melanoma in biopsied mild or moderate DN with positive histologic margins that were clinically observed vs reexcised with negative margins., Design, Setting, and Participants: Retrospective cohort study of mixed referral and community patients from an academic pigmented lesion clinic and dermatology clinics of the affiliated Veteran Affairs medical center with biopsy-confirmed DN with positive histologic margins diagnosed from May 15, 1991, to July 8, 2015, and followed up through May 30, 2016. A consecutive sample of 1473 histologically confirmed DN was identified using surgical pathology databases at the study sites; 590 cases in 498 patients met eligibility criteria., Main Outcomes and Measures: The primary outcome was the proportion of biopsied DN that progressed to histologically confirmed invasive or in situ melanoma. Secondary outcomes included local nevus recurrence and development of primary melanoma at other anatomic sites., Results: The 498 patients had a mean (range) age of 57.6 (14-93) years and 90% were male. Among 590 positive-margin DN, 191 were reexcised and 399 clinically observed without further surgery; 170 reexcised and 304 observed DN had available follow-up data, with mean (SD) follow-up of 5.5 (4.6) years. Cases in the observation group were more likely to demonstrate nevus recurrence than those that were reexcised (3.3% vs 0%; P = .02). Six of 304 (2.0%) observed DN subsequently developed melanoma at the same site, compared with 1 of 170 (0.06%) that were reexcised (P = .43). Five of 6 observed patients who developed melanoma initially underwent partial biopsy with grossly positive margins; 1 melanoma in situ evolved from an excisionally biopsied moderately dysplastic nevus 5 years later. Only 1 case of thin invasive melanoma (≤1 mm) was observed, and no deaths from melanoma arising from biopsy-proven DN occurred through the latest dermatology follow-up. New primary melanoma developed at other sites in 9.9% of excised and 9.4% of resected DN., Conclusions and Relevance: In cases of mild and moderate DN with microscopically positive margins and no concerning clinical residual lesion, observation, rather than reexcision, was a reasonable management option. Partial biopsies of pigmented lesions suspicious for melanoma may lead to delayed melanoma diagnosis and should be discouraged.

Importance: The management of clinically atypical nevi/dysplastic nevi (CAN/DN) is controversial, with few data to guide the process. Management recommendations for DN with positive histologic margins were developed by the Delphi method to achieve consensus among members of the Pigmented Lesion Subcommittee (PLS) of the Melanoma Prevention Working Group (MPWG) after reviewing the current evidence., Objectives: To outline key issues related to the management of CAN/DN: (1) biopsies of CAN and how positive margins arise, (2) whether incompletely excised DN evolve into melanoma, (3) current data on the outcomes of DN with positive histologic margins, (4) consensus recommendations, and (5) a proposal for future studies, including a large-scale study to help guide the management of DN with positive margins., Evidence Review: The literature, including recent studies examining management and outcomes of DN with positive margins between 2009 to 2014, was reviewed., Findings: A consensus statement by the PLS of the MPWG following review of the literature, group discussions, and a structured Delphi method consensus., Conclusions and Relevance: This consensus statement reviews the complexities of management of CAN/DN. A review of the literature and 2 rounds of a structured Delphi consensus resulted in the following recommendations: (1) mildly and moderately DN with clear margins do not need to be reexcised, (2) mildly DN biopsied with positive histologic margins without clinical residual pigmentation may be safely observed rather than reexcised, and (3) observation may be a reasonable option for management of moderately DN with positive histologic margins without clinically apparent residual pigmentation; however, more data are needed to make definitive recommendations in this clinical scenario.

Objective: To evaluate the effect of surgical excision, performed after biopsy diagnosis of dysplastic nevus, on final diagnosis, melanoma prevention, and melanoma detection., Design, Setting, and Participants: Outcome study using retrospective review conducted in an academic dermatopathology practice (Boston Medical Center Skin Pathology Laboratory) that receives specimens from community and academic practices across the United States. Consecutive patient pathology samples of dysplastic nevi and cutaneous melanomas evaluated between September 1, 1999 and March 1, 2011, and identified using systematized nomenclature of medicine codes were included., Main Outcomes and Measures: In dysplastic nevi cases, the rate of clinically significant change in diagnosis and the rate of melanoma detection as a result of excision. In melanoma cases, the rate and characteristics of association with dysplastic nevus., Results: Of dysplastic nevi, 196 of 580 (34%) showed a positive biopsy margin, increasing with grade of atypia (P < .001); 127 of 196 with positive biopsy margin received excision (65%), performed more often as grade of atypia increased (P < .001). Two excisions (2 of 127, 1.6%) resulted in a clinically significant change in diagnosis, from biopsy-diagnosed moderately-to-severely dysplastic nevi before excision to melanoma in situ after excision. In melanomas (n = 216), in situ and superficial spreading subtypes were more often associated with dysplastic nevi (20% and 18%, respectively) (P = .002), most often of moderate-to-severe or severe grade., Conclusions and Relevance: Excision of biopsy-diagnosed mildly or moderately dysplastic nevi is unlikely to result in a clinically significant change in diagnosis, and risk of transformation to melanoma appears very low. Moderately-to-severely and severely dysplastic nevi are more often associated with melanoma, and excision may be beneficial for melanoma detection or prevention.