Contralateral Synchronous Hair Growth of Homologous Digits Following Unilateral Depilation: A Case Report

Background: Whether unilateral local depilation can trigger hair growth in contralateral corresponding regions remains unknown. Methods: A 16-year-old female underwent chemical depilation exclusively on the left little, ring, and middle fingers (intervention group). The untreated right homologous digits served as the control group, while the bilateral index fingers and thumbs served as blank controls. Results: Fifteen days post-intervention, the left treated digits exhibited initial regrowth. Synchronously, the untreated right little, ring, and middle fingers demonstrated a significant increase in hair follicle density and length (18, 30, and 30 hairs, respectively), compared to their left counterparts (7, 18, and 20 hairs). In contrast, the blank control digits showed no significant bilateral differences. Conclusions: This case report documents synchronous contralateral follicular activation in homologous digits following unilateral chemical depilation. This phenomenon suggests a potential unknown neural reflex or systemic symmetric communication mechanism, warranting further investigation.