Definition: recurrence of a benign melanocytic nevus at the site of previous incomplete removal

Most recur within 6 months of removal

Asymmetry, poor circumscription, and variegate pigmentation

Often confluent nested and single melanocytes at dermoepidermal junction

Dermal scar

Monomorphous melanocytes of original nevus

MOST IMPORTANT: Review of previous biopsy to confirm benignity

Sharp circumscription

Intraepidermal melanocytic proliferation does not extend beyond scar

Absence of striking nuclear atypia

Typical melanocytes of nevus beneath scar