Vulval squamous cell carcinoma and its precursors

Vulval squamous cell carcinoma (VSCC) can arise through two distinct pathways [human papillomavirus (HPV)-associated and HPV-independent], and these VSCC variants are recognised as different disease entities on the basis of different aetiologies, morphological features, molecular events during oncogenesis, precursor lesions, prognosis, and response to treatment. The precursor of HPV-associated VSCC, variously referred to as high-grade squamous intraepithelial lesion (HSIL) [vulvar intraepithelial neoplasia (VIN) 2/3] or usual-type VIN, is morphologically identical to the more common HSIL (cervical intraepithelial neoplasia 2/3) of the cervix. The precursor lesions of HPV-independent VSCC include differentiated VIN, differentiated exophytic vulvar intraepithelial lesion, and vulvar acanthosis with altered differentiation; these have been under-recognised by pathologists in the past, leading to delays in treatment. This review will discuss the recent advances in diagnostic surgical pathology of VSCC and its precursors, and how these diagnoses can impact on patient management.     

Aberrant promoter methylation of SH3GL2 gene in vulvar squamous cell carcinoma correlates with clinicopathological characteristics and HPV infection status

Objective: This study attempted to examine the methylation status of SH3GL2 gene in different types of human vulvar lesions and its correlation with clinicopathological parameters. Methods: Immunohistochemical analysis was used to identify the expression status of SH3GL2 in vulvar squamous cell carcinoma (VSCC), vulvar intraepithelial neoplasia (VIN) and benign vulvar squamous epithelium tissues. Bisulfite genomic sequencing method was used to detect methylation status of the SH3GL2 gene. Clinicopathological correlation of the alterations was analysed by the chi-square tests. Results: Immunohistochemical analysis showed expression of SH3GL2 in VSCC was significantly downregulated than that in VIN and normal vulvar tissues. In accordance with higher frequency of methylation status in SH3GL2, statistical analysis showed methylation status of SH3GL2 was closely related to tumor TNM stage (P=0.003), but not related to age, tumor volume, tumor differentiation, lymph node metastasis and VIN grade. High-methylation status of SH3GL2 showed significant association with HPV infection status. Conclusions: Our results indicated that the methylation status of SH3GL2 gene was associated with the TNM staging and HPV infection status of VSCC, suggesting that it might play a synergistic role in the development of VSCC.     

Molecular events in the pathogenesis of vulvar squamous cell carcinoma

Vulvar squamous cell carcinomas (VSCC), which constitute over 90% of vulvar malignancies in adults, are classifiable into 2 subgroups that are mostly clinicopathologically distinct, a classification that is fundamentally based whether or not the tumors are HPV-mediated. In this review, we aim to summarize the recent advances in the understanding of molecular events in the pathogenesis of VSCC, including common and targetable mutations, copy number alterations, epigenetics, noncoding RNAs, and tumor immune microenvironment, which may provide insight into the future management of the disease. These events show substantial differences between the 2 subgroups, although significant areas of overlap exist. Recurrent, driver mutations appear to be substantially more prevalent in HPV(-) VSCC. TP53 mutations are the most common somatic mutations in VSCC overall, and are notably predominant in the HPV(-) VSCC, where 30-88% show a mutation. TP53 mutations are associated with worse patient outcomes, and co-mutations between TP53 and either HRAS, PIK3CA or CDKN2A appear to define subsets with even worse outcomes. A wide variety of other somatic mutations have been identified, including a subset with different mutational frequencies between HPV(+) and HPV(-) VSCC. CDKN2A mutations are common, and have been identified in 21 to 55% of HPV(-) VSCC, and in 2 to 25% of HPV(+) VSCC. Hypermethylation of CDKN2A is the most frequently reported epigenetic alteration in VSCC and the expression of some microRNAs may be associated with patient outcomes. The PTEN/PI3K/AKT/mTOR pathway is commonly altered in HPV(+) VSCC, and is accordingly potentially targetable. HPV-positivity/p16 block expression by immunohistochemistry has been found to be an independent prognostic marker for improved survival in VSCC, and may have some predictive value in VSCC patients treated with definitive radiotherapy. 22-39.3% and 68% of VSCC show EGFR amplification and protein overexpression respectively, although the prognostic and predictive value of an EGFR alteration requires additional study. Recurrent chromosomal gains in VSCCs have been found at 1q, 2q, 3q, 4p, 5p, 7p, 8p, 8q, and 12q, and there may be differential patterns of alterations depending on HPV-status. At least one-third of VSCC patients may potentially benefit from immune checkpoint inhibition therapy, based on a high frequency of PD-L1 expression or amplification, or a high tumor mutational burden. Additional studies are ultimately required to better understand the global landscape of genetic and epigenetic alterations in VSCC, and to identify and test potential targets for clinical application.     

The retinoblastoma protein/p16 INK4A pathway but not p53 is disrupted by human papillomavirus in penile squamous cell carcinoma

Stankiewicz E, Prowse D M, Ktori E, Cuzick J, Ambroisine L, Zhang X, Kudahetti S, Watkin N, Corbishley C & Berney D M
(2011) Histopathology 58 , 433–439
The retinoblastoma protein/p16 ^INK4A pathway but not p53 is disrupted by human papillomavirus in penile squamous cell carcinoma Aims: The pathogenesis of penile squamous cell carcinoma (PSCC) is not well understood. Human papillomavirus (HPV) may be involved in carcinogenesis, but few studies have compared cell‐cycle protein expression in HPV positive and negative cancers. The aim was to determine the extent of HPV infection in different histological subtypes of PSCC and its impact on the expression of key cell‐cycle proteins: p53, p21, p16^INK4A and retinoblastoma (RB) protein. Methods and results: One hundred and forty‐eight PSCC samples were examined immunohistochemically for RB, p16^INK4A, p53 and p21 protein expression. One hundred and two cases were typed for HPV by PCR. HPV DNA was detected in 56% of tumours, with HPV16 present in 81%. Basaloid tumours were related strongly to HPV infection (10 of 13), while verrucous were not (three of 13). Fifty‐nine per cent (38 of 64) of usual type SCCs had HPV infection. RB protein correlated negatively (P < 0.0001) and p16^INK4A (P < 0.0001) and p21 (P = 0.0002) correlated positively with HPV infection. p53 did not correlate with HPV infection. Conclusions: HPV infection is present in more than half of penile cancers and it is responsible for RB pathway disruption. However, no link between HPV and p53 immunodetection was found. Only basaloid and half of usual‐type PSSCs correlate with HPV infection, confirming possible separate aetiologies for those tumours.     

Allelic loss in human papillomavirus-positive and -negative vulvar squamous cell carcinomas

Vulvar squamous cell carcinoma (VSCC) is a biologically and morphologically diverse disease, consisting of human papillomavirus (HPV)-positive and -negative tumors that differ in their morphological phenotypes and associated vulvar mucosal disorders. This study analyzed the frequencies of allelic loss (loss of heterozygosity (LOH)) in HPV-positive and -negative VSCCs to identify potential targets for the study of preinvasive diseases, to determine whether HPV status influenced patterns of LOH, and to determine whether these patterns differed from HPV-positive tumors of another genital site, cervical squamous cell carcinomas (CSCC). DNA extracted from microdissected archival sections of two index tumors, one each HPV negative and positive, was analyzed for LOH at 65 chromosomal loci. Loci scoring positive with either sample were included in an analysis of 14 additional cases that were also typed for HPV. Frequencies of LOH at loci were computed in a panel of HPV-positive and -negative VSCCs. Twenty-nine loci demonstrated LOH on the initial screen and were used to screen the remaining 14 tumors. High frequencies of LOH were identified, some of which were similar to a prior karyotypic study (3p, 5q, 8p, 10q, 15q, 18q, and 22q) and others of which had not previously been described in VSCC (1q, 2q, 8q, 10p, 11p, 11q, 17p, and 21q). With the exception of 5q and 10p, there were no significant associations between frequency of LOH and HPV status in VSCC. LOH at 3p and 11q were frequent in both VSCC and CSCC; however, allelic losses at several sites, including 5q, 8q, 17p, 21q, and 22q, were much more common in VSCC. VSCCs exhibit a broad range of allelic losses irrespective of HPV status, with high frequencies of LOH on certain chromosomal arms. This suggests that despite their differences in pathogenesis, both HPV-positive and -negative VSCCs share similarities in type and range of genetic losses during their evolution. Whether the different frequencies of LOH observed between VSCC and CSCC are real or reflect differences in stage and/or tumor size remains to be determined by further comparisons. The role of these altered genetic loci in the genesis of preinvasive vulvar mucosal lesions merits additional study.     

Premalignant and malignant squamous lesions of the vulva

Vulvar premalignant squamous lesions include low- and high-grade intraepithelial neoplasias. High-grade lesions include classic (usual) and differentiated (simplex) vulvar intraepithelial neoplasia (VIN). Classic VIN (cVIN), the most common, is related to human papilloma virus (HPV), occurs in younger patients, and is frequently multifocal. Differentiated VIN (dVIN), less common, is related to lichen sclerosus and other chronic vulvar dermatoses, occurs in older women, and is usually unifocal. Terminology schemes for premalignant lesions are reviewed. Invasive squamous cell carcinoma also occurs in two distinct clinicopathologic settings. Most conventional keratinizing squamous cell carcinomas arise from a background of dVIN and comprise the majority of invasive squamous tumours. Warty and basaloid invasive squamous cell carcinomas likely develop from cVIN and comprise a minority of invasive tumours. Clinical features, microscopic findings, differential diagnoses, immunoprofile, prognosis and treatment of premalignant and malignant lesions are addressed.     

Codon 72 polymorphism of p53 and HPV type 16 E6 variants as risk factors for patients with squamous epithelial lesion of the uterine cervix

The Arg/Arg genotype versus Arg/Pro or Pro/Pro at codon 72 of the p53 gene in association with human papillomavirus (HPV) 16 E6 variants has been implicated as a risk marker in cervical neoplasia. However, research on this topic has produced controversial results. The association of p53 codon 72 polymorphism alone and in combination with specific HPV 16 E6 variants with risk of developing squamous intraepithelial cervical lesion has been investigated in low and high‐grade squamous intraepithelial lesions and in HPV‐negative controls from an Italian population. The data obtained showed statistically significant different distribution of p53 genotypes between healthy controls and precursor lesions, with the p53 arginine homozygous increased in high‐grade squamous intraepithelial lesions. The T350G HPV 16 variant was the most frequent variant observed in the analyzed group of Italian women, showing a slight decreasing with the severity of the lesion. At the same time, the number of the prototype T350 slightly increased with the severity of the cytological lesions. In conclusion, p53 arginine homozygous was found to be increased in high‐grade lesions, supporting the results of previous investigations indicating that HPV‐positive patients with p53 Arg/Arg have an increased risk of developing pre‐cancerous lesions. In addition, T350G HPV 16 variant was over‐represented in p53 Arg homozygous women with cervical lesions. When p53 genotype and HPV 16 variants are considered together, no difference emerges between cases and controls so is not possible to assess that the oncogenic effect of HPV 16 T350G variant may be influenced by the p53 genotype. J. Med. Virol. 85:83–90, 2012. © 2012 Wiley Periodicals, Inc.     

Premalignant and malignant squamous lesions of the vulva

Vulvar premalignant squamous lesions include low- and high-grade intraepithelial neoplasias. High-grade lesions include usual (classic) and differentiated (simplex) vulvar intraepithelial neoplasia (VIN). Usual VIN (uVIN), the most common, is related to human papilloma virus (HPV), occurs in younger patients, and is frequently multifocal. Differentiated VIN (dVIN), less common, is related to lichen sclerosus and other chronic vulvar dermatoses, occurs in older women, and is usually unifocal. Terminology schemes for premalignant lesions are reviewed. Invasive squamous cell carcinoma also occurs in two distinct clinicopathologic settings. Most conventional keratinizing squamous cell carcinomas arise from a background of dVIN and comprise the majority of invasive squamous tumours. Warty and basaloid invasive squamous cell carcinomas likely develop from uVIN and comprise a minority of invasive tumours. Clinical features, microscopic findings, differential diagnoses, immunoprofiles, prognosis and treatment of premalignant and malignant lesions are addressed.     

Primary squamous cell carcinoma of the vagina: human papillomavirus detection, p16(INK4A) overexpression and clinicopathological correlations

Fuste V, del Pino M, Perez A, Garcia A, Torne A, Pahisa J & Ordi J
(2010) Histopathology 57, 907–916 Primary squamous cell carcinoma of the vagina: human papillomavirus detection, p16 ^INK4A overexpression and clinicopathological correlations Aim: To determine the role of human papillomavirus (HPV) in the pathogenesis of primary squamous cell carcinoma of the vagina (SCCVa), and to evaluate its clinicopathological significance. Methods and results: All cases of SCCVa diagnosed over a 15‐year period from two hospitals in Barcelona, Spain (n = 32) were retrieved. Patients with a history of carcinoma of the cervix diagnosed <5 years before were excluded. HPV was detected and typed by polymerase chain reaction (PCR) using SPF10 primers. Immunohistochemistry was performed for p16 and p53. HPV was detected in 25 cases (78.1%). HPV16 was the most prevalent type. Patients with HPV‐positive tumours were associated frequently with a history of carcinoma or intraepithelial neoplasia of the cervix or vulva diagnosed more than 5 years before (56% versus 0%; P = 0.01). HPV‐positive tumours were more frequently of non‐keratinizing, basaloid or warty type than HPV‐negative neoplasms (84% versus 14.3%; P < 0.001), and showed diffuse positive immunoreactivity for p16^INK4a (96%, versus 14.3%; P < 0.001). The sensitivity and specificity of p16 to identify HPV‐positive tumours were 96% and 85.7%, respectively. Conclusions: A high number of SCCVs are related to HPV infection and may be identified by immunohistochemistry for p16. HPV‐positive tumours tend to affect women with history of cervical neoplasia.     

The role of TP53 in Cervical carcinogenesis

Functional loss of the tumor suppressor p53 by alterations in its TP53 gene is a frequent event in cancers of different anatomical regions. Cervical cancer is strongly linked to infection by high-risk human papillomavirus (HPV) types. The viral oncoprotein E6 has the ability to associate with and neutralize the function of p53. E6 interacts with a 100-kDa cellular protein, termed E6 associated protein (E6AP; also called ubiquitin-protein ligase E3A or UBE3A), which functions as an ubiquitin protein ligase. The dimeric complex then binds p53 and E6AP catalyzes multi-ubiquitination and degradation of p53. The ability to promote p53 degradation is an exclusive property of E6 from the high-risk HPV types. Indeed, the low-risk E6 proteins lack this activity, although they can bind p53. Consistent with the E6 function of the high-risk HPV types, the majority of cervical cancer cells have a wild-type p53 gene, but the protein levels are strongly decreased. Several independent studies have shown that in a small percentage of cervical tumors the p53 gene is mutated. However, this event appears to be unrelated to the presence or absence of HPV infection and the nature of the tumor.     

HPV-assoziierte Ver?nderungen an Vulva und Vagina

Non-neoplastic HPV-induced alterations of the vulva and vagina are frequent. The traditional three-tier grading system of vulvar intraepithelial neoplasia (VIN) will be replaced by the definition of usual and simplex type of VIN. The usual type is characterized by a strong association to high-risk HPV infections, the occurrence at younger age and multifocality, mostly associated with non-keratinizing squamous cell carcinoma. The differentiated (or simplex) type is rare and shows an association to older age and p53 alterations and is typically diagnosed co-incidentally with keratinizing squamous cell carcinoma. Vaginal intraepithelial neoplasia (VAIN) is still graded into VAIN 1-3 where VAIN?1 and 2 are mostly associated with low-risk HPV infections and a high spontaneous regression rate whereas VAIN 3 represents a high-risk HPV-associated lesion with capable progression into (micro-)invasive carcinoma. The differential diagnosis between a non-neoplastic condylomatous lesion and VIN common type and VAIN may be aided by p16 immunohistochemistry. The HPV-associated invasive vulvo-vaginal cancers are verrucous carcinoma (low-risk HPV) and the high-risk HPV-induced (non-keratinizing) squamous cell carcinoma (NOS), the condylomatous (warty) carcinoma and the very rare vaginal squamo-transitional carcinoma.     

Nomenklatur der plattenepithelialen Präkanzerosen des unteren weiblichen Genitales

The majority of precancerous lesions of the lower female genital tract (intraepithelial neoplasia, IN) are caused by human papillomavirus (HPV) infections resulting in cellular atypia and in turn an altered tissue architecture. Depending on the pathogenesis, a distinction is made between vulvar intraepithelial neoplasia (VIN) classified as classical VIN associated with high-risk HPV infections (u-VIN) and differentiated VIN (d-VIN), which is associated with lichen sclerosus et atrophicus and p53 alterations. In the current World Health Organization (WHO) classification a novel grading system for squamous cell precancerous lesions of the lower female genital tract has been proposed, differentiating low grade squamous intraepithelial lesions (L-SIL) including condyloma and HPV-associated alterations plus VIN 1, vaginal intraepithelial neoplasia (VaIN 1) and cervical intraepithelial neoplasia (CIN 1) from high grade squamous intraepithelial lesions (H-SIL) with VIN 2 and 3, VaIN 2 and 3 as well as CIN 2 and 3. The use of p16 immunohistochemistry can assist the differentiation. The new binary classification, however, contradicts the German cytological nomenclature (Munich nomenclature III), which differentiated three grades of dysplasia in order to avoid overtreatment of patients with moderate IN. The individual nomenclatures are compared to each other. It is recommended to report the grade of precancerous lesions in addition to the SIL classification of the WHO.     

Pathologisch-anatomische Aufarbeitung und Befundung von Präparaten bei Präkanzerosen und Karzinomen der Vulva

On the basis of varying morphology and pathogenesis, two types of vulvar intraepithelial neoplasias (VIN) have been defined: the common type (~98%), classic VIN, is characterised by strong association to high-risk HPV infection (up to 90%), occurrence at younger age (median age 30--40 years) and multifocality. The differentiated (or simplex) type is rare (1%--2%) and is associated with older age (median age 65 years) and p53 alterations. It is usually diagnosed in combination with vulvar (keratinizing) squamous cell carcinoma. The classification currently preferred by the WHO in which VIN are classified into VIN 1--3 is to be replaced due to new data and according to a proposal by the International Society for the Study of Vulvovaginal Diseases (ISSVD) which eliminates VIN 1 and combines VIN 2 and 3 to VIN of common or, depending on histopathology, differentiated type. Prognostically relevant factors in vulvar cancer include stage of disease, inguinal lymph node involvement, size of metastatic deposits and presence of extracapsular extension, depth of invasion and distance of the tumor from resection margins. Tumor grade and the presence of lymphovascular space involvement are controversially discussed.     

Increased angiogenesis in the uterine cervix associated with human papillomavirus infection

We studied the relationship between angiogenesis (using the CD34 antibody), the presence of human papilloma virus (HPV) infection, HPV E6 protein expression and the accumulation of p53 protein at various phases of tumour progression in the uterine cervix. Expression of CD34, p53 and HPV E6 protein was evaluated by immunocytochemistry. Presence of the mutant p53 was detected using a mutant specific ELISA, and the type of HPV was determined by the Polymerase Chain Reaction. A total of 230 cervical tissue samples were analyzed and included 40 cases of apparently normal cervical epithelium, 37 low grade squamous intraepithelial lesions (SILs), 43 high grade SILs, 36 well-differentiated squamous cell carcinomas (DSCC), 31 moderately differentiated (MDSCC) and 43 poorly differentiated carcinomas (PDSCC). There was an excellent correlation between the extent of angiogenesis and histological abnormality (r = 0.912, p = 0.000004). The least extent of angiogenesis was seen in normal cervical tissue and low grade SILs where the mean (low power) intra lesional vascular density (ILVD) was 12 +/- 1.13 and 25.66 +/- 5.20, respectively. In high grade squamous intraepithelial lesions (SILs), the mean ILVD value was 80.84 +/- 25.57. In well-differentiated squamous cell carcinomas (WDSCC's) the mean value was 144.22 +/- 28.67 while in moderately differentiated squamous cell carcinomas (MDSCC's) the mean value was 166.29 +/- 34.95 and in poorly differentiated tumours (PDSCC's) 192.42 +/- 27.98. The extent of angiogenesis also correlated to presence of HPV (r = 0.505, p = 0.00001). Increased CD34 expression was associated with the presence of HPV types 16 and 18. A similar correlation was also evident in HPV, 16/18 infected cases expressing the E6 protein (r = 0.612, p = 0.000001). CD34 expression also correlated well with p53 accumulation (r = 0.859, p = 0.000002). Presence of HPV infection significantly correlated with the extent of histological abnormality (r = 0.467, p = 0.00001). Expression of E6 also showed this significant correlation (r = 0.644, p = 0.00002). Accumulation of p53 was significantly more elevated in HPV 16-infected lesions (r = 0.518, p = 0.00001) and E6-expressing cells (r = 0.650, p = 0.000004). Only 12 of the 230 cases analyzed showed presence of the mutant p53 protein. Angiogenesis appears to increase with histological abnormality in the uterine cervix. Angiogenesis also appears to be influenced by high risk HPV infection, the expression of the E6 transforming protein and the p53 tumour suppressor protein.     

Isolation and functional analysis of five HPVE6 variants with respect to p53 degradation

Persistent infection with high risk human papillomavirus is a necessary risk factor in the etiology of invasive cervical carcinoma. With regard to molecular details, the best studied types are HPV16 and HPV18 which are found in 70% of cervical cancer worldwide, however factors associated with the progression of individual cervical intraepithelial neoplasias into cancer are still poorly understood. Intratype amino acid variations in the immortalizing and transforming early proteins E6 and E7 were described to be associated with progressive disease and linked to increased viral persistence or progression. One of the key actions of high risk HPVE6 proteins is the inhibition of the function of p53, a tumor suppressor protein, by enhancing its degradation through the ubiquitin pathway. In this study, variants of five HPV type E6 proteins (HPV35, 53, 56, 66, and 70) isolated from patient materials are described and functional analysis of them were done with respect to p53 degradation. Interestingly the E6 protein of HPV type 53, which has no consistent risk classification in the literature showed the highest variability in our study. The analysis of all variants revealed no differences with regard to the degradation ability for p53 compared to the prototype E6 proteins, suggesting that the variants tested revealed no altered functions related to the carcinogenicity of the respective HPV types. It therefore seems more likely that variations in the E6 gene sequence may allow evasion from the hosts immune system, supporting increased viral persistence.     

Interplay between human papilloma virus infection and p53 gene alterations in head and neck squamous cell carcinoma of an Indian patient population

AIM: To investigate the complex interplay between human papilloma virus (HPV) infection and p53 gene alteration in 92 head and neck squamous cell carcinoma (HNSCC) and 28 leukoplakia samples from eastern India. METHODS: DNA isolated from the patient samples was subjected to HPV detection, loss of heterozygosity (LOH) analysis of the chromosome 17p region harbouring p53, genotyping at the p53 codon 72 locus and sequencing of the entire p53 gene to identify somatic mutations. Codon 72 heterozygotes carrying the p53 mutation were further cloned and resequenced to identify the allele harbouring the mutation. RESULTS: HPV positivity in the HNSCC samples was 69%; 21% of the HNSCC were found to harbour p53 mutations in the coding region of the gene. The absence of the p53 mutation in HPV positive tumours was statistically significant compared to the HPV negative tumours (p = 0.01), but the same did not hold true for p53 LOH (p = 1.0). Among the germline p53 codon 72 heterozygotes, the Pro allele was preferentially lost (p = 0.02) while the Arg allele was mutated in the majority of cases. The risk of HPV mediated tumourigenesis increased with the increase in number of Arg alleles at the codon 72 locus. CONCLUSION: It is proposed that genetic and epigenetic alteration of p53 follow distinct pathways during the development of HNSCC from normal epithelium via dysplasia. The p53 mutation and HPV mediated p53 inactivation possibly constitute two independent pathways of tumourigenesis.