Immunohistochemistry in vaginal pre-invasive lesions
| Lesion | Histochemistry/immunohistochemistry | Comment |
| HSIL (VaIN 2/3) | p16 block positivity, Ki-67 extends above basal layers through the entire epithelium. p63 and p40 will confirm squamous origin, if in doubt | Ki-67 will stain above the basal layers in LSIL as well and cannot be used to distinguish LSIL from HSIL. p16 is more useful in this distinction. |
| Adenosis | Mucicarmine or periodic acid shift (PAS reaction) with and without diastase will highlight mucin producing cells | |
| Pagetoid spread of urothelial intraepithelial neoplasia | Positive cytokeratin 7, cytokeratin 20, p63, and GATA3 staining149 and uroplakin150 | Exceptionally rare |
| Paget disease | Cells are positive for PAS-D, mucicarmine, CK 7, GCDFP-15, GATA3151 | Exceptionally rare. Stains to distinguish secondary Paget disease of urothelial (including uroplakin150) or anorectal origin (including CDX-2, CK20152) should be considered in appropriate cases |
| Melanoma in situ | Positivity for s100, Melan-A, and HMB 45153 | Exceptionally rare. A panel to distinguish melanoma in situ from Paget disease can be helpful |
HSIL, high-grade squamous intraepithelial lesions; LSIL, low-grade squamous intraepithelial lesions; VaIN, vaginal intraepithelial neoplasia.