Chapter 1: Histopathology of gynaecological cancers
Vulvar tumours
The majority of vulvar cancers are squamous cell carcinomas (VSCCs), which are divided into HPV-associated and HPV-independent tumours.
Other entities diagnosed at this location include Paget disease, invasive adenocarcinoma, basal cell carcinoma, melanoma, adnexal tumours, mesenchymal tumours and metastases (Figure 1.19).
Figure 1.19: Vulvar melanoma; H&E staining and expression of HMB45, Melan A and vimentin
Abbreviations: H&E, haematoxylin and eosin.
Credit: Courtesy of the authors
Immunostaining for p16 is a surrogate marker of HPV infection, although there is not full concordance between HPV infection and p16 staining.
Squamous cell neoplasia, HPV-associated: low-grade and high-grade vulvar intraepithelial neoplasia (VIN) is the precursor of HPV-associated VSCC (Figure 1.20).
Figure 1.20: High-grade VIN
Abbreviations: VIN, vulvar intraepithelial neoplasia.
Credit: Courtesy of the authors.
Transformation by HPV involves the same mechanism as in cervical carcinoma, and p16 immunostaining and HPV typing are used similarly in the diagnostic setting.
HPV-associated VSCCs affect younger women compared with HPV-independent VSCCs and have better stage-matched survival than the latter. Histopathological grading has no prognostic value.
Squamous cell neoplasia, HPV-independent: differentiated VIN (dVIN), often associated with lichen sclerosus, is the precursor of HPV-independent VSCC.
Tumours often carry TP53 mutations, and aberrant p53 immunostaining is seen in dVIN and invasive carcinomas (Figure 1.21).
Figure 1.21: Differentiated VIN (dVIN)
Abbreviations: VIN, vulvar intraepithelial neoplasia.
Credit: Courtesy of the authors
The initial site of metastasis from VSCC, both HPV-associated and HPV-independent, is inguinal lymph nodes.
Revision Questions
- Which malignant tumour is most common in the vulva?
- Does HPV status have a role in classifying VSCC?
- What is the name of the precursor lesions of VSCC and which immunostains are relevant?
