Evaluating Rates of Positive Margins After Standard Excision of Cutaneous Adnexal Malignancies.

Background: It is recommended to excise adnexal neoplasms with standard local excision or Mohs micrographic surgery (MMS), although many occur on high-risk sites such as the head and neck (H&N) and exhibit subclinical extension. Minimal evidence exists on the efficacy of standard excisions for these tumors.

Objective: To evaluate the rate of positive surgical margins after standard excision of adnexal tumors.

Methods: Retrospective cohort study of cutaneous adnexal malignancies from the National Cancer Database diagnosed from 2004 to 2019.

Results: The authors identified a total of 4,402 cases treated with standard excision. Tumors on the H&N were approximately twice as likely as those on the trunk and extremities (T&E) to be excised with positive margins (odds ratio 2.146, p < .001), with the highest estimated rate for eccrine adenocarcinoma (12.1%, SE: 2.3%). The subtype with the highest positive margin rate on the T&E was microcystic adnexal carcinoma (8.0%, SE: 2.9). Positive margins were associated with poorer overall survival on multivariable survival analysis (hazard ratio 1.299, p = .015).

Conclusion: The authors present subtype- and site-specific positive margin rates for adnexal tumors treated with standard excision, which suggest that tumors on the H&N and some T&E subtypes, should be considered for MMS.