Clinical Characteristics of Marginally Recurrent Melanoma After Primary Excision: A Multisite Retrospective Analysis of 140 Cases Referred for Mohs Surgery.

Abstract

Marginally recurrent melanoma (MRM) manifests immediately adjacent to or within a scar and arises from incomplete tumor clearance after primary treatment. Little is known about the progression and treatment of MRM after all forms of excision. To determine the invasive growth potential, tumor-stage progression, and outcomes of those with MRM. One hundred forty patients with MRM were collected from 5 practice databases. All patients were treated with Mohs micrographic surgery. They were evaluated for Breslow depth and tumor stage change from the time of primary treatment and recurrent treatment. Of 101 cases initially treated as melanoma in situ, 13 (12.9%) marginally recurred with invasive disease at the time of Mohs micrographic surgery. The median thickness of these recurrent melanomas was 0.58 mm. Of 39 cases initially treated as invasive melanoma, 10 (25.6%) marginally recurred with a greater Breslow depth. The median increase in thickness from initial treatment to recurrence was 1.31 mm. Marginally recurrent melanoma retains its invasive growth potential. This can lead to Breslow depth increase, tumor-stage progression, and a worse prognosis on recurrence. Obtaining tumor-free margins is critical in initial and recurrence treatments.