[5 min read] Excisionally biopsied dysplastic naevi with positive histologic margins: observe or re-excise?

Can moderately dysplastic naevi that have been excisionally biopsied with no residual clinical pigmentation but with positive histologic margins be closely observed instead of re-excised?

Little evidence exists to guide the management of moderately dysplastic naevi excisionally biopsied without residual clinical pigmentation but with positive histologic margins. US researchers sought to determine the outcomes and risk for the development of subsequent cutaneous melanoma from moderately dysplastic naevi with positive histologic margins observed for three years or more.

They conducted a multi-centre cohort study of 467 moderately dysplastic naevi with positive histologic margins from 438 patients (193 women and 245 men, with an average age of 46.1 years). However, 100 patients developed a cutaneous melanoma at a separate site. Results of multivariate analyses revealed that history of cutaneous melanoma was significantly associated with the risk of development of subsequent cutaneous melanoma at a separate site (odds ratio, 11.74; 95% CI, 5.71-24.15; P < .001), as were prior biopsied dysplastic naevi (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, one was interpreted as melanoma in situ. That patient remains without recurrence or evidence of cutaneous melanoma after five years of follow-up.

To summarise, the study found no cases of cutaneous melanoma at the biopsy site after an average follow-up time of 6.9 years. However, patients with two or more biopsied dysplastic naevi had an increased risk of developing a subsequent cutaneous melanoma at a separate site.

These findings suggest that close observation with routine skin surveillance is a reasonable management approach for moderately dysplastic naevi with positive histologic margins. However, having two or more biopsied dysplastic naevi (with one that is a moderately dysplastic naevus) appears to be associated with increased risk for subsequent cutaneous melanoma at a separate site.

Read more recent research on dysplastic naevi.

Source: Kim CC, Berry EG, Marchetti MA, et al. Risk of Subsequent Cutaneous Melanoma in Moderately Dysplastic Nevi Excisionally Biopsied but With Positive Histologic Margins. JAMA Dermatol. 2018;154(12):1401–1408. doi:10.1001/jamadermatol.2018.3359

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