TABLE 3.

Definition of Basal Nuclear Atypia in Vulvar Squamous Neoplasia

Nuclear feature	Common feature of atypia	Less common feature of atypia
Chromatin	Hyperchromatic • Dense chromatin • Nucleoli not well seen	Vesicular • Open chromatin • Enlarged eosinophilic nucleoli • Double or multiple nucleoli • Occasional binucleation
Enlargement	Diffuse marked enlargement • More than triple the size of a lymphocyte nucleus Obviously different to nuclei in nonneoplastic epithelium	Variable enlargement • Most nuclei double the size of a lymphocyte nucleus Difference between abnormal and normal nuclei highlighted by overexpressed p53
Pleomorphism	Marked cell-to-cell variation Irregularly shaped cells	Cell-to-cell variation present Majority of cells show uniform shape with enlarged vesicular nuclei
Mitoses	Increased • >1 per 1-mm basal layer length	Abnormal mitotic figures • Y-shaped, X-shaped • Pieces of extra chromosomes separate to the main mitotic spindle