Residual atypical intraepidermal melanocytic proliferation may predict melanoma diagnosis

Increasing proportions of atypical intraepidermal melanocytic proliferation on various parts of the body may increase the likelihood of a diagnostic change to melanoma after Mohs micrographic surgery, according to findings presented at the American Society for Dermatologic Surgery Annual Meeting.

Jeremy Etzkorn, MD, assistant professor of dermatology at the Hospital of the University of Pennsylvania, Philadelphia, and colleagues suggested that surgical margins and patient counseling for atypical intraepidermal melanocytic proliferation and melanoma may be different.

The retrospective, cross-sectional study included 198 patients with atypical intraepidermal melanocytic proliferation on the head, neck, hands and feet. Eligible participants underwent Mohs micrographic surgery at the University of Pennsylvania between August 2008 and March 2016.

The researchers obtained consent for analysis of patient photographs for 118 atypical intraepidermal melanocytic proliferations, of which 99 were on the head and neck and 19 were on the hands and feet. The researchers compared preoperative and postoperative diagnoses.

Results indicated that 35.6% of the atypical intraepidermal melanocytic proliferation patients experienced a change of diagnosis to melanoma after surgery. This included 40 patients with in situ and two with invasive malignancies.

Multivariable analysis results indicated that the only factor significantly associated with a change in diagnosis was the percentage of pigment remaining after preoperative biopsy (OR = 1.42 per 10% increase in pigment; P = .0001). This factor yielded an area under the curve of 0.803 for diagnostic change.

Patients who experienced a diagnostic change had a median of 87.5% of clinically visible residual pigment. The 25th percentile of residual pigment was 77%, while the 75th percentile was 93.8%. By comparison, among patients without a diagnostic change, the amount of clinical visible residual pigment was 52.65% (Mann-Whitney U comparison statistic, 569; P < .001). For this variable, the 25th percentile was 0%, while the 75th percentile was 79.4%.

“The likelihood of a diagnostic change to melanoma increases with the percentage of visible residual pigment of [atypical intraepidermal melanocytic proliferation] on the head, neck, hands and feet,” they concluded. “Patients should receive appropriate preoperative counseling about their elevated risk for diagnostic change to melanoma prior to surgery when significant residual pigment is present after the diagnostic biopsy.” – by Rob Volansky

Reference:

Etzkorn J, et al. Diagnostic change from atypical intraepidermal melanocytic proliferation (AIMP) to melanoma is more likely when clinically visible residual pigment remains after biopsy. Presented at: American Society for Dermatologic Surgery Annual Meeting; Oct. 5-8, 2017; Chicago.

Disclosures: The authors report no relevant financial disclosures.