Figure 1.

Low-grade squamous intraepithelial lesion (LSIL/AIN-1). The low-grade lesion is typically characterized by marked superficial cell atypia (bracket) with nuclear enlargement and nuclear membrane contour irregularity with preserved nucleus-to-cytoplasm ratio. Bi-nucleation is often seen (arrow). The lower third of the squamous epithelium has more uniform appearance with minmal nuclear variation. Inset: higher power view of nuclear irregularities, along with perinuclear clearing (koilocytic change, arrowheads) [Hematoxylin and eosin (H&E) 400x; inset 600x]