Mohs Micrographic Surgery With Immunohistochemistry for the Treatment of Periocular Melanoma In Situ

Abstract

Purpose: Mohs micrographic surgery with immunohistochemistry allows for same-day comprehensive margin assessment of melanoma in situ prior to subspecialty reconstruction. This study describes the oncologic and reconstructive outcomes of eyelid and periorbital melanoma in situ and identifies risk factors for complex reconstructive demands. Methods: Retrospective case series of all patients treated with Mohs micrographic surgery with immunohistochemistry for melanoma in situ affecting the eyelids or periorbital region from 2008 to 2018 at a single institution. Tumors were assigned to the eyelid group if the clinically visible tumor involved the skin inside the orbital rim. Reconstructive variables were compared between the eyelid and periorbital cohorts. Results: There were 24 eyelid and 141 periorbital tumors included. The initial surgical margin for all tumors was 5.34 ± 1.54 mm and multiple Mohs stages were required in 24.2% of cases. Eyelid tumors included more recurrences (p = 0.003), and the average defect size was larger (14.0 ± 13.3 cm2 vs. 7.7 ± 5.4 cm2, p = 0.03). Risk factors for complex reconstruction included: initial tumor diameter >2 cm (odds ratio [OR]: 3.84, 95% confidence interval [CI]: 1.95–7.57) and eyelid involved by initial tumor (OR: 4.88, 95% CI: 1.94–12.28). At an average follow-up of 4.8 years, there were no melanoma-related deaths and 1 local recurrence (0.6% recurrence rate). Conclusions: Mohs micrographic surgery with immunohistochemistry achieves excellent local control rates for periocular melanoma in situ. An initial surgical margin of 5 mm is frequently insufficient to achieve clear margins. The resulting defects are large, and the complexity of reconstruction can be predicted by tumor size and clinical involvement of eyelid skin.