Experimental Factor Ontology id EFO_0022937 (high grade vulvar squamous intraepithelial lesion) is an intraepithelial lesion of the vulvar squamous epithelium associated with HPV infection. It is characterized by loss of maturation, nuclear hyperchromasia, high nuclear:cytoplasmic ratios, cytological and architectural atypia, and mitoses. Two morphological patterns have been described: basaloid (undifferentiated) and warty (condylomatous, bowenoid). It carries a significant but relatively low risk of progression to squamous cell carcinoma if untreated. (WHO 2020).