Adnexal squamous cell carcinoma: incidence of eyelid margin involvement.

PURPOSE: We aimed to perform a review of facial and periorbital squamous cell carcinoma (SCC) cases to assess the relative incidence of eyelid margin involvement. METHODS: This is a retrospective review of all patients with biopsy-proven SCC who were evaluated at a single oculoplastic surgery practice from 2007 to 2019. The charts were reviewed for the anatomical location of the malignancy, and those involving the eyelid were further divided into marginal and non-marginal lesions. Statistical analysis was performed using a one proportion z-test. RESULTS: A total of 76 patients with a diagnosis of biopsy-proven periorbital and facial SCC were identified, 67 involved the ocular adnexa. Thirty-nine (58.2%) patients had lesions located on the eyelid. Of these, 33 (84.6% p < 0.0001, 95% CI 69.45-94.13) had lesions located at the margin, six of the 39 lesions were non-marginal. The remaining lesions were present within the brow (n = 10, 14.9%), medial canthus (n = 10, 14.9%), palpebral conjunctiva (n = 1, 1.5%), or orbit (n = 1, 1.5%). In six patients (8.9%) lesions involved multiple anatomic subunits. CONCLUSION: We present our investigation of the incidence of SCC of the marginal vs. non-marginal eyelid, revealing a statistically significant increased involvement of the eyelid margin. Future investigations are necessary to further elucidate the vulnerability of the eyelid margin to the development of SCC in particular in regards to the role of the unique genetic expression profile of eyelash follicular stem cells.