LAUSR

BACKGROUND Microcystic adnexal carcinoma (MAC) is a locally aggressive and deeply infiltrative cutaneous tumor primarily treated with excision; however, there are limited data comparing outcomes by surgical approach. OBJECTIVE To compare surgical outcomes of MAC treated with Mohs micrographic surgery (MMS) and wide local excision (WLE). METHODS A 27-year retrospective cohort study of primary MAC was performed. Surgical (i.e. margin status after resection) and recurrence outcomes (including local recurrence [LR], nodal metastases [NM], and distance metastases [DM]) were analyzed by type of surgical approach (MMS and WLE). RESULTS Sixty-nine MACs were included, of which 34 (49.3%) were treated with MMS and 35 (50.7%) with WLE. All MMS-treated tumors had negative margins after the first surgery attempt. Twenty-one (60.0%) tumors treated with WLE had positive margins after the first surgical attempt and required additional procedures. More tumors treated with WLE developed LR, NM, or DM, although this did not meet statistical significance. LIMITATIONS Retrospective single institution study. CONCLUSION Greater than half of MAC tumors treated with WLE had positive margins after the initial surgery and required multiple procedures for complete removal. Real-time complete margin assessment is important for this locally aggressive and infiltrative tumor.