The Hair-Cut Sign for Scalp Biopsy Site Identification

Accurate localization of the biopsy site before Mohs micrographic surgery (MMS) can be difficult on the scalp, where hair often obscures key anatomic landmarks. Failure to accurately identify the biopsy site may result in wrong-site surgery, a serious and preventable surgical error. The hair-cut sign is a simple, no-cost technique in which hairs transected during biopsy leave a short tuft that persists as surrounding hairs grow, marking the biopsy site for weeks to months. This technique requires no additional equipment and integrates easily into clinic workflow. It is most effective in patients with longer hair and shorter biopsy-to-surgery intervals and should complement-not replace-standard documentation practices.