Background: No guidelines for the margin of resection of cutaneous squamous cell carcinoma have been based on data measuring subclinical tumor extension, as have been formulated for basal cell carcinoma.
Objective and methods: Guidelines for appropriate margins of excision of primary cutaneous squamous cell carcinoma were formulated on the basis of a prospective study of subclinical microscopic tumor extension.
Results: Four millimeter margins were adequate for most squamous cell carcinomas. However, certain tumor characteristics were associated with a greater risk of subclinical tumor extension and included size of 2 cm or larger, histologic grade 2 or higher, invasion of the subcutaneous tissue, and location in high-risk areas.
Conclusion: Minimal margins of excision of 4 mm around the clinical borders of the squamous cell carcinoma are proposed for all but the high-risk tumors, in which at least a 6 mm margin is recommended.