Differential etiopathogenic features of vulvar squamous cell carcinomas in sub-Saharan Africa and Europe

A Narrative Review of the Vulvar Disease Literature With Images of Women of Color

OBJECTIVE

To assess the existing literature on vulvar disease in women of color (WOC).

METHODS

A narrative review was conducted to assess the literature on vulvar disease in WOC and evaluate the presence of images in this population. The search encompassed PubMed and OVID using relevant terms related to vulvar conditions and various groups of WOC. Case reports, as well as posters were excluded. Books on this topic were searched using these two search engines and Google, as well as the Taubman Health Sciences Library at the University of Michigan. This library contains numerous books on vulvar diseases commonly used by health care providers.

RESULTS

This query identified 24 journal publications on vulvar diseases in WOC. Twenty-six books, commonly used by health care providers, were found to have been published with vulvar images of WOC. However, only 1 focused specifically on vulvar diseases in WOC.

CONCLUSIONS

There is a notable scarcity of articles and books addressing vulvar conditions specifically in WOC. This gap in literature limits the understanding of how these conditions may uniquely affect this demographic population. Additional research and resources are essential to effectively represent and meet the health needs of WOC.

Interpretation of p16 and p53 in the Classification of Squamous Cell Carcinoma of the Vulva-An Interobserver Agreement Study

Squamous cell carcinoma of the vulva (vSCC) is currently categorized either as human papillomavirus (HPV) associated or independent. Immunohistochemical stains, p16 INK4a (p16) and p53 are helpful biomarkers to support the designation of vSCC into 1 of the 3 tumor pathways: (1) HPV-associated, (2) HPV-independent, TP53 mutant, or (3) HPV-independent, TP53 wild type. Recently, a framework of p53 expression patterns in vSCC was proposed. In this international and multi-institutional study, we evaluated the interrater agreement for p53 and p16 and tumor pathway classification in a cohort of 50 invasive vSCC across a variety of practice settings (private practice, academic medicine) and levels of expertise (trainees, gynecologic pathologists, dermatopathologists, private practice pathologists). Our study shows that the overall interrater agreement for the interpretation of p16 in vSCC is strong to near perfect, while the agreement for p53 and tumor pathway assignment is overall moderate. Interrater agreement for p53 and tumor pathway is higher (strong) in the academic practice setting. Pathologists without gynecologic subspecialty expertise benefited the most from a brief educational module, which fostered a better understanding and improved comfort level with the p16/p53 stain interpretation and tumor pathway designation in the diagnosis of vSCC. Some interpretative challenges remain, particularly in regard to select p53 patterns and high-risk HPV-in situ hybridization utilization, warranting additional research.

Simultaneous p53 and p16 Immunostaining for Molecular Subclassification of Head and Neck Squamous Cell Carcinomas

PURPOSE

Our aim was to assess the ability of simultaneous immunohistochemical staining (IHC) for p16 and p53 to accurately subclassify head and neck squamous cell carcinomas (HNSCC) as HPV-associated (HPV-A) versus HPV-independent (HPV-I) and compare p53 IHC staining patterns to TP53 mutation status, p16 IHC positivity and HPV status.

METHODS

We stained 31 HNSCCs for p53 and p16, and performed next-generation sequencing (FoundationOne©CDx) on all cases and HPV in-situ hybridization (ISH) when sufficient tissue was available (n = 23). p53 IHC staining patterns were assessed as wildtype (wt) or abnormal (abn) patterns i.e. overexpression, null or cytoplasmic staining.

RESULTS

In a majority of cases (28/31) interpretation of p16 and p53 IHC was straightforward; 10 were considered HPV-A (p16+/p53wt) and 18 cases were HPV-I (p16-/p53abn). In the remaining three tumours the unusual immunophenotype was resolved by molecular testing, specifically (i) subclonal p16 staining and wild type p53 staining in a tumour positive for HPV and with no TP53 mutation (HPV-A), (ii) negative p16 and wild type p53 staining with a TP53 mutation and negative for HPV (HPV-I), and (iii) equivocally increased p16 staining with mutant pattern p53 expression, negative HPV ISH and with a TP53 mutation (HPV-I).

CONCLUSION

Performing p16 and p53 IHC staining simultaneously allows classification of most HNSCC as HPV-A (p16 +, p53 wild type (especially basal sparing or null-like HPV associated staining patterns, which were completely specific for HPV-A SCC) or HPV-I (p16 -, p53 mutant pattern expression), with the potential for limiting additional molecular HPV or mutational testing to selected cases only.

High concordance of molecular subtyping between pre-surgical biopsy and surgical resection specimen (matched-pair analysis) in patients with vulvar squamous cell carcinoma using p16- and p53-immunostaining

OBJECTIVE

Vulvar squamous cell carcinoma (VSCC) can be stratified into three molecular subtypes based on the immunoexpression of p16 and p53: HPV-independent p53-abnormal (p53abn) (most common, biologically aggressive), HPV-associated, with p16-overexpression (second most common, prognostically more favourable) and more recently recognised HPV-independent p53-wildtype (p53wt) (rarest subtype, prognostically intermediate). Our aim was to determine whether molecular subtypes can be reliably identified in pre-operative biopsies and whether these correspond to the subsequent vulvectomy specimen.

METHODS

Matched-paired pre-surgical biopsies and subsequent resection specimen of 57 patients with VSCC were analysed for the immunohistochemical expression of p16 and p53 by performing a three-tiered molecular subtyping to test the accuracy rate.

RESULTS

Most cases 36/57 (63.2%) belonged to the HPV-independent (p53-abn) molecular subtype, followed by HPV-associated 17/57 (29.8%) and HPV-independent (p53wt) 4/57 (7.0%). The overall accuracy rate on biopsy was 91.2% (52/57): 97.3% for p53-abnormal, 94.1% for p16-overexpression and 50% for p16-neg/p53-wt VSCC. Incorrect interpretation of immunohistochemical p53 staining pattern was the reason for discordant results in molecular subtyping in all five cases. In one case there was an underestimation of p53 pattern (wildtype instead of abnormal/aberrant) and in one case an overestimation of the p53 staining pattern (abnormal/aberrant instead of wildtype). In 3/5 there was a "double positive" staining result (p16 overexpression and abnormal/aberrant p53 staining pattern). In that cases additional molecular workup is required for correct molecular subtyping, resulting in an overall need for molecular examination of 3/57 (3.5%).

CONCLUSIONS

Compared to the final resections specimen, the three-tiered molecular classification of VSCC can be determined on pre-surgical biopsies with a high accuracy rate. This enables more precise surgical planning, prediction of the response to (chemo) radiation, selection of targeted therapies and planning of the optimal follow-up strategy for patients in the age of personalised medicine.

Classification of Vulvar Squamous Cell Carcinoma and Precursor Lesions by p16 and p53 Immunohistochemistry: Considerations, Caveats, and an Algorithmic Approach

There is emerging evidence that vulvar squamous cell carcinoma (VSCC) can be prognostically subclassified into 3 groups based on human papillomavirus (HPV) and p53 status: HPV-associated (HPV+), HPV-independent/p53 wild-type (HPV-/p53wt), or HPV-independent/p53 abnormal (HPV-/p53abn). Our goal was to assess the feasibility of separating VSCC and its precursors into these 3 groups using p16 and p53 immunohistochemistry (IHC). A tissue microarray containing 225 VSCC, 43 usual vulvar intraepithelial neoplasia (uVIN/HSIL), 10 verruciform acanthotic vulvar intraepithelial neoplasia (vaVIN), and 34 differentiated VIN (dVIN), was stained for p16 and p53. Noncomplementary p16 and p53 patterns were resolved by repeating p53 IHC and HPV RNA in situ hybridization (ISH) on whole sections, and sequencing for TP53. Of 82 p16-positive VSCC, 73 (89%) had complementary p16 and p53 patterns and were classified into the HPV+ group, 4 (4.9%) had wild-type p53 staining, positive HPV ISH and were classified into the HPV+ group, whereas 5 (6.1%) had p53 abnormal IHC patterns (1 null, 4 overexpression), negativity for HPV ISH, and harbored TP53 mutations (1 splice site, 4 missense); they were classified as HPV-/p53abn. Of 143 p16-negative VSCC, 142 (99.3%) had complementary p53 and p16 patterns: 115 (80.4%) HPV-/p53abn and 27 (18.9%) HPV-/p53wt. One had a basal-sparing p53 pattern, positivity for HPV ISH and was negative for TP53 mutations-HPV+ category. The use of IHC also led to revised diagnoses-HSIL to dVIN (3/43), dVIN to vaVIN (8/34), and dVIN to HSIL (3/34). Overall, 215/225 VSCC (95.6%) could be easily classifiable into 3 groups with p16 and p53 IHC. We identified several caveats, with the major caveat being that "double-positive" p16/p53 should be classified as HPV-/p53abn. We propose an algorithm that will facilitate the application of p16 and p53 IHC to classify VSCC in pathology practice.

Penile Squamous Cell Carcinomas in Sub-Saharan Africa and Europe: Differential Etiopathogenesis

Penile squamous cell carcinomas (PSCC) are classified by the World Health Organization into two categories based on their relationship with the human papillomavirus (HPV): HPV-associated and HPV-independent. We compared a cohort of PSCC from Mozambique, a sub-Saharan country in southeast Africa with a high prevalence of HPV and HIV infection, and Spain, a country in southwestern Europe with a low prevalence of HPV and HIV, to study the distribution of the etiopathogenic categories of these tumors in both sites. A total of 79 PSCC were included in the study (28 from Mozambique and 51 from Spain). All cases underwent HPV-DNA polymerase chain reaction (PCR) testing, genotyping, and immunohistochemistry for p16 and p53. Any PSCC showing either p16 overexpression or HPV-DNA in PCR analysis was considered HPV-associated. Overall, 40/79 (50.6%) tumors were classified as HPV-associated and 39 (49.4%) as HPV-independent. The two sites showed marked differences: 25/28 (89.3%) tumors from Mozambique and only 15/51 (29.4%) from Spain were HPV-associated (p < 0.001). HPV16 was the most frequent HPV type identified in 64.0% (16/25) of the HPV-associated tumors from Mozambique, and 60.0% (9/15) from Spain (p = 0.8). On average, patients from Mozambique were almost two decades younger than those from Spain (mean age 50.9 ± 14.9 and 69.2 ± 13.3, respectively [p < 0.001]). In conclusion, significant etiopathogenic differences between PSCC in Mozambique and Spain were observed, with a remarkably high prevalence of HPV-associated tumors in Mozambique and a relatively low prevalence in Spain. These data may have important consequences for primary prevention of PSCC worldwide.