Switching from an AIMP to a melanoma diagnosis

The likelihood of a diagnostic change to melanoma increases with the percentage of visible residual pigment of AIMP on the head, neck, hands and feet, researchers reported at the 2017 American Society for Dermatologic Surgery annual meeting in Chicago on Oct. 5.

It is known that melanoma is detected in as many as 13% of atypical intraepidermal melanocytic proliferation (AIMP) diagnosed lesions on the head, neck, hands, and feet. In this study, led by Jeremy Etzkorn, M.D., of the University of Pennsylvania, researchers closely examined the variables that may predict changing a diagnosis from AIMP to melanoma after the results of Mohs micrographic surgery.

This was a single site, retrospective, observational cross-sectional study of 118 atypical intraepidermal melanocytic proliferation (AIMP) lesions on the head, neck, hands and feet (99 on the head and neck and 19 on the hands and feet). The lesions were treated with Mohs micrographic surgery at the University of Pennsylvania between August 2008 and March 2016.

Of 118 AIMP lesions, 42 (35.6%) diagnoses were changed to melanoma post-op (including 40 in situ and 2 invasive melanoma).

Researchers evaluated the association between changing the diagnosis from AIMP to melanoma based on the following factors:  percentage of pigment remaining after diagnostic biopsy, age, sex, history of previous treatment, number of pre-operative biopsies, melanoma in the initial biopsy’s histopathologic differential diagnosis, the presence of pagetoid spread in the biopsy specimen, lesion extension to the base of the biopsy specimen, lesion extension to the lateral aspect of the biopsy specimen, and the use of an excisional biopsy technique.

Of these, the percentage of pigment remaining after the preoperative biopsy was the only factor that was “significantly” associated with a diagnostic change to melanoma (OR 1.42, 95% CI). In this group, 87.5% of cases had a median of clinically visible residual pigment which compares to 52.65% for the group without a diagnostic change.

“Patients should receive appropriate pre-operative counseling about their elevated risk for diagnostic change to melanoma prior to surgery when significant residual pigment is present after the diagnostic biopsy,” researcher urged.

Reference

Olivia Jew; Christopher Miller, MD; Thuzar Shin, MD, PhD; Joseph Sobanko, MD. “Diagnostic Change from Atypical Intraepidermal Melanocytic Proliferation (AIMP) to Melanoma is More Likely When Clinically Visible Residual Pigment Remains After Biopsy,” American Society for Dermatologic Surgery annual meeting in Chicago, Thursday, Oct. 5, 2017.