BACKGROUND : Deep transection of invasive melanoma precludes accurate measurement of Breslow depth, which may affect tumor staging.

OBJECTIVE : To determine the frequency of upstaging of transected invasive melanomas after excision, characterize the impact on National Comprehensive Cancer Network (NCNN)-recommended treatment, and determine predictors of subsequent upstaging.

MATERIALS AND METHODS : A retrospective review of invasive melanomas between January 2017 and December 2019 at a single institution. Deeply transected biopsy reports were compared with subsequent excisions to calculate the frequency of upstaging.

RESULTS : Three hundred sixty (49.6%) of 726 invasive melanomas identified were transected. Forty-nine (13.6%) transected tumors had upstaging that would have altered NCCN-recommended management. "Broadly" transected tumors had upstaging that would have resulted in a change in the management in 5/23 cases (21.7%) versus 2/41 cases (4.9%) for "focally" transected tumors (p = .038). Breslow depth increased by 0.59 mm on average for "broad" transection versus 0.06 mm for "focal" transection (p =< .01). Of the 89 transected pT1a melanomas, specimens with gross residual tumor or pigment after biopsy were upstaged in 8/17 (47.1%) of cases versus 5/72 (6.9%) of specimens without (p =< .01).

CONCLUSION : Upstaging of deeply transected invasive melanomas that would alter NCCN-recommended management occurred in 13.6% of cases. Broad transection and gross residual tumor or pigment after biopsy predicted higher likelihood of upstaging.