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.     

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.     

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.     

Presence and type of oncogenic human papillomavirus in classic and in differentiated vulvar intraepithelial neoplasia and keratinizing vulvar squamous cell carcinoma

The presence and type of oncogenic papillomavirus (HPV) in classic warty/basaloid vulvar intraepithelial neoplasia and in differentiated vulvar intraepithelial neoplasia and keratinizing vulvar squamous cell carcinoma was investigated using three techniques, that is, histology, in situ hybridization, and PCR-ELISA. HPV typing was performed using in situ hybridization and PCR-ELISA. Differentiated vulvar intraepithelial neoplasia and invasive keratinizing vulvar squamous cell carcinoma proved completely negative for HPV by PCR-ELISA, in situ hybridization, and histologic examination, while in classic vulvar intraepithelial neoplasia, a HPV positivity of 66.1% was found. HPV 16 was the predominant type, with HPV 35, 33, and 52 types found rarely and sometimes together with HPV 16. PCR-ELISA proved to be the most suitable method to detect and type mucosal oncogenic HPVs. The absolute absence of HPV DNA in differentiated vulvar intraepithelial neoplasias and in keratinizing vulvar squamous cell carcinoma suggests a strong HPV-independent pathway of malignant progression to invasive carcinoma.     

Specific intraepithelial localization of mast cells in differentiated vulvar intraepithelial neoplasia and its possible contribution to vulvar squamous cell carcinoma development

van de Nieuwenhof H P, Hebeda K M, Bulten J, Otte‐Holler I, Massuger L F A G, de Hullu J A & van Kempen L C L T
(2010) Histopathology 57, 351–362
Specific intraepithelial localization of mast cells in differentiated vulvar intraepithelial neoplasia and its possible contribution to vulvar squamous cell carcinoma development Aims: The aetiology of vulvar squamous cell carcinomas (SCC) that are not causally associated with high‐risk human papillomavirus remains largely elusive. The aim of this study was to analyse the inflammatory response in its presumed precursor lesions, lichen sclerosus (LS) and differentiated vulvar intraepithelial neoplasia (dVIN), and provide evidence that dVIN is a likely precursor of vulvar SCC. Methods and results: Immunohistochemical analyses for CD4+, CD8+, CD20+, CD68+, S100+ and tryptase‐positive immune cells were performed and quantified in LS (n = 7), dVIN (n = 19), SCC (n = 11), and normal vulvar tissue (n = 8). The subepithelial inflammatory response in dVIN and SCC was comparable, but absent in LS. Abundant intraepithelial mast cells were observed in dVIN only, and confirmed by electron microscopy, toluidine blue staining and cKIT expression. Adjacent keratinocytes displayed increased proliferation as determined by MIB‐1 positivity. Electron microscopy revealed intraepithelial mast cell degranulation. Intraepithelial mast cells were not or infrequently observed in vulvar hyperplasia (n = 13), condylomata acuminata (n = 5), keratinocytic intraepidermal neoplasia of sun‐exposed skin (n = 15), epidermal hyperplasia of head and neck (n = 12), and psoriasis (n = 3). Conclusions: These data indicate that dVIN can be recognized by intraepithelial mast cells and that they might promote the progression of dVIN to SCC.     

Differentiated dysplasia is a frequent precursor or associated lesion in invasive squamous cell carcinoma of the oral cavity and pharynx

The source of precursor lesions of squamous cell carcinoma (SCC) of the oral cavity and pharynx, their classification, and grading are controversial. In contrast, vulvar and penile cancer precursor lesions are known to be related to human papillomavirus or chronic inflammation and can be described using the vulvar intraepithelial neoplasia (VIN) classification system (VIN 1–3) or as differentiated vulvar intraepithelial neoplasia (dVIN), respectively. Oral and pharyngeal SCC precursor lesions are more etiologically diverse, and the spectrum of lesions may thus be wider. No international consensus exists regarding the histological types of precursor lesions or the significance of individual types. We therefore reviewed resection specimens and preceding biopsies of 155 patients with SCC of the oral cavity and pharynx (excluding tonsils) and identified five basic patterns of SCC-associated or precursor lesions: (1) pleomorphic (22/155), (2) basaloid (5/155), (3) differentiated (63/155), (4) mixed (42/155), and (5) verrucous (12/155). Keratinization was a common but variable feature in differentiated, mixed, and verrucous dysplasia. In 11/155 patients, no precursor lesion could be identified. Progression of isolated differentiated dysplasia (ranging from months to years) was documented in 13/155 (8 %) of patients. Our data suggest that full-thickness epithelial dysplasia of pleomorphic or basaloid type is present in <20 % of oral and pharyngeal SCC, and differentiated dysplasia is a frequent precursor or associated in situ lesion. Failure to recognize differentiated dysplasia results in the underdiagnosis of many patients at risk for invasive carcinoma. These results indicate a need to refine criteria to distinguish differentiated dysplasia from morphologically related lichenoid lesions.     

Pathways of vulvar intraepithelial neoplasia and squamous cell carcinoma

Vulvar squamous cell carcinoma (VSCC) accounts for >90% of the malignant tumours of the vulva. Most VSCCs originate in intraepithelial lesions, named vulvar intraepithelial neoplasia (VIN), that precede the development of VSCC by a variable period of time. Strong evidence has accumulated showing that there are two different aetiopathogenic pathways for the development of VSCC and VIN, one associated with infection by human papillomavirus (HPV), and a second independent of HPV infection. These two different types of VSCC have different epidemiological, pathological and clinical characteristics, and should therefore be considered as two separate entities. Histologically, HPV‐associated VSCCs are of the basaloid or warty type, and arise from VIN of the usual type. Inactivation of p53 and the retinoblastoma tumour suppressor gene product by the viral gene products E6 and E7 is involved in the process of malignant transformation. HPV‐independent VSCCs are histologically keratinizing, are associated with differentiated VIN and lichen sclerosus, and frequently show mutations of p53. p16^INK4a and p53 immunostaining can be useful for classifying VSCC into HPV‐associated or HPV‐independent. Although large, multicentre studies are needed to definitively assess the involvement of HPV in the prognosis of VSCC, most studies have not found clear differences in survival between HPV‐associated and HPV‐independent tumours.     

Review of precancerous vulvar lesions

Classification of squamous vulvar precancerous lesions is based on the concept of vulvar intraepithelial neoplasia (VIN) and incorporates a three grade evaluation of the intensity of dysplastic changes (VIN I, II and III). On the basis of histological features, VIN has been subdivided into the usual VIN (u-VIN) and differentiated VIN (d-VIN), which represent the two basic pathways of the pathogenesis of vulvar squamous cell carcinoma. Although u-VIN is etiologically associated with the human papillomavirus (HPV) infection and histologically corresponds to cervical intraepithelial neoplasia, d-VIN represents the HPV-negative sequence of vulvar carcinogenesis, which is linked to lichen sclerosus (LS) and lichen simplex chronicus (LSC). u-VIN preferentially occurs in relatively young women with a history of cervical, vaginal or vulvar premalignant lesions. On the other hand, d-VIN usually affects postmenopausal women without anamnestic data of other dysplastic lesions of the lower female genital tract. d-VIN is characterized by a higher tendency of stromal invasion than u-VIN and its malignant potential is analogous to carcinoma in situ (VIN III). The histological appearance of d-VIN is subtle with basal atypia and a well-preserved differentiation of the superficial parts of the squamous epithelium, therefore it is frequently misdiagnosed for u-VIN I, LS or LSC in vulvar biopsies. Primarily because of the low diagnostic reproducibility of the u-VIN I category and the doubts about its precancerous potential as well as due to the questionable differentiation between u-VIN II and III, a revised VIN classification was proposed in 2004. The grading of vulvar precancerous lesions was abandoned, the u-VIN I category was discontinued and u-VIN II and III were merged. In the revised terminology, the term u-VIN represents HPV-associated high grade precancerous vulvar lesions (formerly u-VIN II and III) and d-VIN encompasses HPV-negative high grade dysplasias. Keywords: vulvar intraepithelial neoplasia - VIN of the usual type - VIN of the differentiated type - lichen sclerosus - lichen simplex chronicus - HPV.     

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.     

Updates in the pathology of penile intraepithelial neoplasia

Penile intraepithelial neoplasia (PeIN) is the putative histologic precursor of penile squamous cell carcinoma. PeIN is classified into HPV-associated and HPV-independent (differentiated) (dPeIN). While HPV-associated PeIN is has been linked to the oncogenic effect of human papillomavirus (HPV), the HPV-independent pathway is driven by chronic inflammatory conditions. These two biologic pathways are associated with distinct histopathologic features. The most common morphologic patterns of HPV-associated PeIN are basaloid, warty, and mixed PeIN. DPeIN is the morphologic expression of HPV-independent PeIN. This review will focus on the epidemiological, etiologic, and pathogenetic aspects of PeIN, as well as the morphologic patterns of the two major categories of PeIN. Furthermore, recent 2022 WHO updates will be discussed.     

Vulvar keratinizing squamous cell carcinoma in a 26-year-old woman

A 26-year-old Hispanic woman complaining of "itching" and "herpetic lesions" on the vulva for 9 months was seen at a university hospital. On physical examination, multiple vulvar masses were noted. Biopsies taken from these lesions showed invasive keratinizing squamous cell carcinoma. The vulvectomy specimen revealed 4 tumor masses, the largest located on the mons pubis. Although the incidence of vulvar intraepithelial neoplasia has increased in recent years, only very few cases of invasive carcinoma have been reported in young women. The tumors that occur at a younger age characteristically have basaloid or warty histology, in contrast to those occurring in older women, which usually are well-differentiated keratinizing carcinomas. We believe this is an unusual case of vulvar squamous cell carcinoma. In addition to our patient's young age, her tumor had a histologic profile usually found in lesions of an elderly woman. The tumor was negative for human papillomavirus by polymerase chain reaction analysis and was positive for p53 by immunohistochemistry.     

Vulvar carcinomas: search for sequences homologous to human papillomavirus and herpes simplex virus DNA

Ten cases of intraepithelial carcinoma, five with Bowenoid features and five with early invasion, and ten cases of invasive vulvar carcinoma were examined by in situ hybridization and Southern blot analysis using DNA probes for human papillomavirus (HPV) types 6, 11, 16, 18 and 31. HPV DNA was detected in 90% of the intraepithelial cases and in 10% of the invasive cases. All positive cases showed the presence of DNA of HPV type 16. The cases with intraepithelial lesions revealed a strong correlation between the presence of HPV type 16 DNA, cigarette smoking habit, other potential cofactors such as herpes simplex (HSV) DNA sequences and the use of contraceptive drugs, and clinicopathologic features of Bowen's type in situ squamous cell carcinoma. Similar associations were not observed among the cases with invasive disease. While HPV-16 is associated with differentiated Bowenoid type vulvar intraepithelial neoplasia, which appears to be the most common form of early carcinoma of the vulva, the same association was not seen with respect to advanced vulvar invasive squamous cell 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.     

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.     

Monoclonal origin of vulvar intraepithelial neoplasia and some vulvar hyperplasias.

Squamous neoplasms of the female genital tract, including vulvar intraepithelial neoplasia, presumably are derived from a single cell. This study addressed this hypothesis and determined the clonal status of other squamous epithelial alterations associated with vulvar carcinoma, including hyperplasia and lichen sclerosis. X chromosome inactivation patterns of 22 epithelial lesions and matched normal epithelium were determined using a polymerase chain reaction (PCR)-based assay targeting the X-linked human androgen receptor gene (HUMARA). Clonality was inferred by comparing matched lesional and control tissues as follows: 1) monoclonal, if intensity of either PCR product was skewed relative to normal reference epithelium (control), 2) polyclonal, if both lesional and control were unskewed, and 3) unknown, if both lesion and control tissues were skewed toward the same allele. Two cases were excluded because of noninformative homozygous HUMARA alleles. Of 8 vulvar intraepithelial neoplasias analyzed, 7 were scored monoclonal and 1 polyclonal. Of 12 hyperplasias, 6 were monoclonal, including one with lichen sclerosis, 2 were polyclonal, and in 4, the clonal status could not be determined. The PCR-based clonal assay supports a monoclonal derivation for vulvar intraepithelial neoplasia and, in some cases, vulvar hyperplasia, and lichen sclerosis. The finding of monoclonal hyperplasia and lichen sclerosis suggests that clonal expansion may evolve before the development of morphological atypia in these epithelia.     

A review of prognostic factors in squamous cell carcinoma of the vulva: Evidence from the last decade

Squamous cell carcinoma of the vulva is a rare gynecologic cancer that is associated with significant patient morbidity and mortality, particularly for recurrent disease. This review summarizes the evidence and continued challenges, regarding the traditional clinicopathologic factors used to prognosticate vulvar squamous cell carcinoma. Articles published within the last 10 years (2010–2020) were identified. Relevant articles concerning the following fifteen prognostic factors were reviewed: HPV/p16 status, vulvar intraepithelial neoplasia, patient age, tumor stage, tumor grade, tumor size, depth of invasion, stromal changes, histologic patterns of invasion, lymphovascular space invasion (LVSI), perineural invasion, lymph node metastases, tumour focality, margin status and lichen sclerosus (LS). The relationship between each prognostic factor and progression-free survival (PFS) and overall survival (OS), including hazard ratios, 95% confidence intervals and p-values, were extracted.     

Small vulvar squamous cell carcinomas and adjacent tissues. A morphologic study

Vulvar squamous cell carcinomas are of different subtypes and degrees of differentiation, and may be associated with adjacent lichen sclerosus and/or varying degrees of dysplasia. The aim of this investigation was to study small carcinomas with a diameter of less than 2 cm in order to find a possible relation between subtypes of carcinomas and adjacent epithelial changes. Fourteen cases of small vulvar squamous cell carcinomas were totally embedded in paraffin. Serial sectioning made a detailed mapping of all different lesions possible, and a two- and three-dimensional imaging was obtained in each case. Seven patients with keratinizing squamous cell carcinomas (median age 65) had adjacent lichen sclerosus. All carcinomas were completely surrounded by areas of VIN1. VIN2 and VIN3 were not found. Seven patients without lichen sclerosus (median age 58) showed squamous cell carcinomas of the keratinizing type (n=2) or the basaloid type (n=5). Five of these cases were incompletely surrounded by varying degrees of dysplasia, mainly VIN2 and VIN3. Two different pathogenetic pathways for the development of vulvar squamous cell carcinoma are likely.     

外阴营养不良、外阴鳞状上皮细胞癌凝集素标记免疫组化分析

目的：探讨外阴营养不良增生型,硬化苔藓型表皮细胞和外阴鳞状上皮细胞癌等细胞膜结构与凝集素受体结合表达特征及它们三者之间的关系。方法：对慢性外阴营养不良表皮增生型,苔藓硬化型及外阴鳞状上皮细胞癌3种状态下的细胞进行了8种凝集素免疫组织化学标记,分析,比较。结果：外阴营养不良增生型表皮各层细胞细胞膜与刀豆凝集素（ConA),扁豆凝集素（LCA）,花生凝集素（PNA）,蓖麻凝集素（RCA－1）和大豆凝集素（SBA）结合强度弱,其表皮细胞细胞核膜与ConA,PNA和麦胚凝集素（WGA）有中等强度结合,外阴营养不良硬化苔藓型表皮各层细胞细胞膜与ConA,RCA-1 SBA和WGA结合强度弱,而与LCA不结合,其12例中的8例与荆豆凝集素（UEA－1）发生较弱的结合,外阴鳞状上皮细胞癌癌细胞与8种凝集素均结合,其12例中的7例其癌细胞膜与双花扁豆凝集素（DBA）弱结合,癌细胞膜与UEA－1强结合,但癌巢中央细胞团不与UEA－1结合,癌细胞细胞核膜与ConA,LCA,RCA-1呈强结合。结论：凝集素标记免疫组织化学染色可作为诊断,鉴别诊断外阴营养不良增生,硬化苔藓型和外阴鳞状上皮细胞癌新的指标,具有恶变潜能的增生型外阴营养不良与外阴鳞状上皮细胞癌,两者细胞核膜凝集素标记有相似之处,提示在外阴组织的癌变过程中,细胞核膜凝集素标记的异常表达是一个早期标识,糖基和糖蛋白代谢的异常可能是细胞发生癌变最早期的表现之一。