Reexamining the Threshold for Reexcision of Histologically Transected Dysplastic Nevi

Abstract

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 (0.6%) 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 (Յ1 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.

Surgical re-excision vs. observation for histologically dysplastic naevi: a systematic review of associated clinical outcomes

“…One of these melanomas developed out of the 159 excisional biopsies and the other five melanomas were detected out of 145 partial biopsies, suggesting incomplete initial sampling . Among mild‐to‐moderate HDN in the re‐excision group, one of 170 (0·6%) developed melanoma at the biopsy site . In Reddy et al ., among the 127 moderate‐to‐severe HDN followed for an unspecified amount of time, two (2%) were upgraded to melanoma in situ at the biopsy site after re‐excision .…”

“…In Fleming et al ., among mild‐to‐moderate HDN with a mean follow‐up of 5·5 years (range 14 to 93 years), six of the 304 (2%) in the observation developed melanoma . One of these melanomas developed out of the 159 excisional biopsies and the other five melanomas were detected out of 145 partial biopsies, suggesting incomplete initial sampling . Among mild‐to‐moderate HDN in the re‐excision group, one of 170 (0·6%) developed melanoma at the biopsy site .…”

“…that evaluated exclusively HDN with severe atypia, two (1%) patients were diagnosed with melanoma upon re‐excision and none developed metastatic melanoma at follow‐up of 10 years . In Fleming et al ., among mild‐to‐moderate HDN with a mean follow‐up of 5·5 years (range 14 to 93 years), six of the 304 (2%) in the observation developed melanoma . One of these melanomas developed out of the 159 excisional biopsies and the other five melanomas were detected out of 145 partial biopsies, suggesting incomplete initial sampling .…”

“…Only one study was not conducted in the U.S.A. (it was in New Zealand). More than half (seven of 12, 58%) of the included studies had primary outcomes focused on the development of melanoma at the site of HDN biopsy, with a third of studies assessing recurrence of HDN (four of 12, 33%), and one study assessing both outcomes (one of 12, 8%) . Half of the studies did not provide any demographic information about the study population …”

“…The duration of follow‐up time was not specified at all in a quarter of the studies, a minimum duration of follow‐up was specified in three studies (at least 2 years; at least 5 years) and a maximum duration of follow‐up was specified in part of one study (less than 5 years) . When quantified, follow‐up was less than 5 years (range 2–16 weeks; mean 3·56 years, range 1·17–8·72 years) in two studies, it was between 5 and 10 years in two studies (mean ± SD 5·5 ± 4·6 years; mean 6·17 years, range 5·03–9·78 years) and greater than 10 years in two studies (median 11·9 years, interquartile range 9–14·8 years; mean 17·4 years, range: 0–29·9 years).…”