A 63-year-old female former smoker was examined for 6 mo (A and B) and 12 mo (C) after a surgical excision of severe epithelial dysplasia on the left lateral tongue. A, white-light image of a well-healed scar on the left lateral tongue (arrow); B, the anterior aspect of this scar (arrow) under fluorescent visualization showing a dark brown region of autofluorescence loss. C, at 12 mo, the same area (arrow) showed a persistent autofluorescence loss of increased size; at 20 mo after initial treatment (data not shown), a biopsy from the region of loss (arrow) showed carcinoma in situ.