Compliance with sentinel lymph node biopsy guidelines for invasive melanomas treated with Mohs micrographic surgery

Background Sentinel lymph node biopsy (SLNB) has not been studied for invasive melanomas treated with Mohs micrographic surgery using frozen-section MART-1 immunohistochemical stains (MMS-IHC). The primary objective of this study was to assess the accuracy and compliance with National Comprehensive Cancer Network (NCCN) guidelines for SLNB in a cohort of patients who had invasive melanoma treated with MMS-IHC. Methods This retrospective cohort study included all patients who had primary, invasive, cutaneous melanomas treated with MMS-IHC at a single academic center between March 2006 and April 2018. The primary outcomes were the rates of documenting discussion and performing SLNB in patients who were eligible based on NCCN guidelines. Secondary outcomes were the rate of identifying the sentinel lymph node and the percentage of positive lymph nodes. Results In total, 667 primary, invasive, cutaneous melanomas (American Joint Committee on Cancer T1a-T4b) were treated with MMS-IHC. The median patient age was 69 years (range, 25-101 years). Ninety-two percent of tumors were located on specialty sites (head and/or neck, hands and/or feet, pretibial leg). Discussion of SLNB was documented for 162 of 176 (92%) SLNB-eligible patients, including 127 of 127 (100%) who had melanomas with a Breslow depth >1 mm. SLNB was performed in 109 of 176 (62%) SLNB-eligible patients, including 102 of 158 melanomas (65%) that met NCCN criteria to discuss and offer SLNB and 7 of 18 melanomas (39%) that met criteria to discuss and consider SLNB. The sentinel lymph node was successfully identified in 98 of 109 patients (90%) and was positive in 6 of those 98 patients (6%). Conclusions Combining SLNB and MMS-IHC allows full pathologic staging and confirmation of clear microscopic margins before reconstruction of specialty site invasive melanomas. SLNB can be performed accurately and in compliance with consensus guidelines in patients with melanoma using MMS-IHC.