Classic Vulvar Intraepithelial Neoplasia With Superimposed Lichen Simplex Chronicus: A Unique Variant Mimicking Differentiated Vulvar Intraepithelial Neoplasia

A large sample-based case-control study of related risk factors of two types of lichenoid vulvar disease (LVD)

PURPOSE

The purpose of this study is to identify the associated factors of two types of lichenoid vulvar disease (LVD) and to compare the differences in related factors between the different pathological types of lichenoid vulvar disease (LVD).

METHODS

The study conducted at the West China second Hospital of Sichuan University included a total of 1770 patients with biopsy-confirmed vulvar lichen simplex chronicus (VLSC)and vulvar lichen sclerosus(VLS), along with 1209 patients with normal vulvovagina as control. Further pathological subtype analysis was carried out on 163 cases of vulvar lichen simplex chronicus and 51 cases of vulvar lichen sclerosus. In addition, Univariate chi-square test and multivariate logistic regression were used to analyze the lichenoid vulvar disease group and vulvovaginal normal control group.

RESULTS

Univariate analysis revealed that there were statistically significant differences (P < 0.05) in factors between the LVD group and the control group, except for living type, sleep habit, history of drinking, and allergic diseases. There was no significant difference in late sleep, spicy diet, and coffee intake in the factors of life and eating habits and the concomitant disease factors. Furthermore, univariate analysis showed that except for eating seafood, humid living environment, residence, caffeinated drinks, hypertension, and vaginitis, there were statistical differences in the related factors of LVSC.

CONCLUSION

The incidence about lichenoid vulvar disease is influenced by various factors such as dietary habits, living environment, mental stress, concomitant diseases, hormone levels and so on, and there were no significant differences in these factors between VLS and VLSC except for income, work stress, systemic immune diseases, and menopause.

The Importance of p16 and p53 Immunohistochemical Staining in Diagnosing Vulvar Lichen Simplex Chronicus Mimicking Vulvar Intraepithelial Neoplasia with False-Positive Human Papillomavirus Type 66

Vulvar intraepithelial neoplasia (VIN), the precursor lesion of vulvar squamous cell carcinoma (VSCC), may present as pruritic or asymptomatic lichenified plaques surrounded by single or multiple discrete or confluent macules or papules. VIN is divided into high-grade squamous intraepithelial lesion (HSIL), which is human papillomavirus (HPV)-driven, and differentiated VIN (DVIN), which develops independently of HPV. Histopathological examination and HPV genotyping polymerase chain reaction (PCR) tests should be performed to distinguish between HSIL and DVIN. Lichenified plaques surrounded by multiple papules are found not only in VIN but also in vulvar lichen simplex chronicus (LSC). This chronic inflammatory skin disease mostly appears in labia majora and is triggered by sweating, rubbing, and mental stress. IHC staining of p16 and p53 are recommended as the most commonly used biomarkers for VIN in diagnostically challenging cases. IHC staining is also beneficial to confirm the accuracy of the HPV detection technique, as p16-negative staining may also represent a false-positive result. We report a case of the importance of p16 and p53 IHC staining in diagnosing vulvar LSC mimicking VIN with false-positive HPV-66. The patient was previously diagnosed with VIN based on clinical examination. HPV-66 was detected by PCR from a vulvar biopsy sample. Histopathological examination revealed stromal lymphocytic infiltration with non-specific chronic dermatitis; neither atypia nor koilocyte was observed. Both p16 and p53 IHC staining were negative. The patient was diagnosed and treated as vulvar LSC with 10 mg cetirizine tablet, emollient, and 0.1% mometasone furoate cream. Clinical improvement was observed as the lesions became asymptomatic hyperpigmented macules in the 4 weeks of follow-up, without recurrence after 3 years of follow-up. Both p16 and p53 IHC staining might help distinguish HSIL and DVIN mutually and from other vulvar mimics in diagnostically challenging cases.

High-grade vulvar intraepithelial neoplasia: comprehensive characterization and long-term vulvar carcinoma risk

AIMS

Adequate diagnosis of human papillomavirus (HPV)-associated high-grade squamous intraepithelial lesion (HSIL) and HPV-independent vulvar intraepithelial neoplasia (VIN) is essential but can be challenging. We comprehensively characterized a large population-based series of vulvar lesions, originally reported as high-grade VIN, and assessed the cancer risk.

METHODS AND RESULTS

Baseline high-grade VIN of 751 patients were categorized by histopathological reassessment, integrating the results of immunohistochemistry (p16INK4a , p53, Ki-67) and HPV DNA testing. Integrated analyses resulted in 88.4% HPV-associated lesions (77.0% HSIL, 10.9% low-grade SIL [LSIL], and 0.4% vulvar squamous cell carcinoma [VSCC]), 10.9% HPV-independent lesions (6.1% HPV-independent VIN, 4.7% nondysplastic lesions, and 0.1% VSCC) and 1.1% inconclusive lesions. HSIL demonstrated p16INK4a block-positivity in 99.0%, increased Ki-67 in ≥2/3rd of the epithelium in 93.6%, and HPV positivity in 99.6%. In HSIL, a p53 wildtype mid-epithelial staining pattern was common (51.6%) while this was not observed in HPV-independent lesions. HPV-independent VIN harboured mutant p53 patterns in 65.2% and showed a wide morphological spectrum, ranging from differentiated to nondifferentiated ('HPV-associated-like', in 41.3%). Kaplan-Meier analyses showed a 10-year cancer risk of 8.0% in HPV-associated HSIL, 67.4% in HPV-independent VIN/p53mutant, and 27.8% in HPV-independent VIN/p53wildtype. Strikingly, the 10-year cancer risk was 73.3% in HPV-independent VIN with nondifferentiated ('HPV-associated-like') morphology.

CONCLUSION

Immunohistochemistry by p16INK4a and p53 is highly recommended for optimal categorization into HPV-associated and HPV-independent VIN, which is of utmost importance given the different cancer risk. The high cancer risk of HPV-independent VIN underscores the need for surgical treatment and close follow-up, especially in case of a p53 mutant pattern and/or nondifferentiated morphology.

Interobserver Agreement Across Subspecialties for Diagnosis of Differentiated Vulvar Intraepithelial Neoplasia and Predictive Values of 20 Histologic Features

CONTEXT.—

Differentiated vulvar intraepithelial neoplasia (dVIN) is a human papillomavirus-independent lesion with the potential for rapid progression to invasive squamous cell carcinoma (SCC). The histopathologic features of dVIN are diverse, have overlapping characteristics with lichen sclerosus (LS) and lichen simplex chronicus (LSC), and may be diagnosed by dermatopathologists or gynecologic pathologists because of the vulva's anatomic location.

OBJECTIVES.—

To identify the salient histopathologic features of dVIN, particularly those that predict progression to SCC, and to evaluate interobserver agreement in diagnosing dVIN within the same subspecialty and across subspecialties.

DESIGN.—

One general surgical pathologist, 2 pathology-trained dermatopathologists, and 1 gynecologic pathologist blinded to the final diagnoses were asked to record 20 histopathologic features and to provide their final interpretations on cases of dVIN (n = 65), LS (n = 126), LSC (n = 112), and LS with LSC (n = 6).

RESULTS.—

Interobserver agreement for the 4 diagnoses and 10 histopathologic features was moderate. Logistic regression analysis indicated that keratin pearls, basal pleomorphism, and basal layer disarray were independent variables for diagnosing dVIN (coefficients 1.95, 1.97, and 0.91, respectively; P < .001) and progression to SCC (coefficients 1.96, 1.20, and 1.08, respectively; P < .001).

CONCLUSIONS.—

There is no single histopathologic feature pathognomonic for dVIN; however, the presence of keratin pearls, basal pleomorphism, and basal layer disarray should raise high suspicion for dVIN and concurrent SCC. Expertise in both dermatologic and gynecologic pathology is beneficial for diagnosing dVIN.

Pagetoid Squamous Intraepithelial Neoplasia of the Vulva as a Mimicker of Vulvar Extramammary Paget Disease: Two Cases with Basal Layer Sparing

Human papillomavirus-associated vulvar intraepithelial neoplasia (high-grade squamous intraepithelial neoplasia [HSIL] or VIN of usual type) is a lesion characterized by atypia extending from the basal layer to the upper epidermis. There are only rare reports of vulvar intraepithelial morphology exhibiting a pagetoid pattern of intraepithelial dissemination. We herein report two cases of vulvar HSIL in which a pagetoid pattern of spread and a largely uninvolved basal layer represented a diagnostic pitfall for extramammary Paget disease. Nuclear atypia reminiscent of HSIL in addition to expression of p16, KRT5/6, and p40 were however in favor of pagetoid HSIL. Although there is morphological and immunohistochemical overlap between these two entities, an accurate diagnosis is important, since an erroneous diagnosis of vulvar extramammary Paget disease may lead to an extensive workup comprising radiological imaging, colonoscopy, and cystoscopy.

P53 in Penile Squamous Cell Carcinoma: A Pattern-Based Immunohistochemical Framework with Molecular Correlation

p53 immunohistochemistry (IHC) has been proposed as a surrogate for TP53 mutations in penile squamous cell carcinomas (PSCC). We aimed to evaluate the performance of a pattern-based evaluation of p53 IHC in PSCC. Human papilloma virus (HPV) DNA testing, p16 and p53 IHC, and whole exome sequencing were performed in a series of 40 PSCC. p53 IHC was evaluated following a pattern-based framework and conventional p53 IHC evaluation. Out of 40 PSCC, 12 (30.0%) were HPV-associated, and 28 (70.0%) were HPV-independent. The agreement between the p53 IHC pattern-based evaluation and TP53 mutational status was almost perfect (k = 0.85). The sensitivity and accuracy of the pattern-based framework for identifying TP53 mutations were 95.5% and 92.5%, respectively, which were higher than the values of conventional p53 IHC interpretation (54.5% and 70.0%, respectively), whereas the specificity was the same (88.9%). In conclusions, the pattern-based framework improves the accuracy of detecting TP53 mutations in PSCC compared to the classical p53 IHC evaluation.

HPV-independent, p53-wild-type vulvar intraepithelial neoplasia: a review of nomenclature and the journey to characterize verruciform and acanthotic precursor lesions of the vulva

Vulvar squamous cell carcinomas and their precursors are currently classified by the World Health Organization based on their association with high-risk human papillomavirus (HPV). HPV independent lesions often harbor driver alterations in TP53, usually seen in the setting of chronic vulvar inflammation. However, a group of pre-invasive vulvar squamous lesions is independent from both HPV and mutant TP53. The lesions described within this category feature marked acanthosis, verruciform growth and altered squamous maturation, and over the last two decades several studies have added to their characterization. They have a documented association with verrucous carcinoma and conventional squamous cell carcinoma of the vulva, suggesting a precursor role. They also harbor recurrent genomic alterations in several oncogenes, mainly PIK3CA and HRAS, indicating a neoplastic nature. In this review, we provide a historical perspective and a comprehensive description of these lesions. We also offer an appraisal of the terminology used over the years, going from Vulvar Acanthosis with Altered Differentiation and Verruciform Lichen Simplex Chronicus to Differentiated Exophytic Vulvar Intraepithelial Lesion and Vulvar Aberrant Maturation, the latter term having been recently proposed by the International Society for the Study of Vulvovaginal Diseases. In line with the recognition of these lesions by the 2020 World Health Organization Classification of Tumours as a neoplastic precursor, we herein propose the term HPV-independent, p53-wild-type verruciform acanthotic Vulvar Intraepithelial Neoplasia (HPVi(p53wt) vaVIN), which better conveys not only the pathology but also the neoplastic nature and the biologic risk inherent to these uncommon and challenging lesions. We outline strict morphologic and immunohistochemical criteria for its diagnosis and distinction from mimickers. Immunohistochemistry for p16 and p53 should be performed routinely in the diagnostic work-up of these lesions, and the morphologic alternative term vaVIN should be reserved for instances in which p16/HPV/p53 status is unknown. We also discuss management considerations and the need to further explore precursors within and beyond the spectrum of verruciform acanthotic vulvar intraepithelial neoplasia.

Comorbid Vulvar Lichen Sclerosus and High-Grade Squamous Intraepithelial Lesions: A Management Conundrum

OBJECTIVE

This study aimed to determine if treating lichen sclerosus (LS) with high-potency topical corticosteroids (TCS) increases the risk of high-grade squamous intraepithelial lesion (HSIL) recurrence in patients with comorbid vulvar LS and HSIL.

METHODS

This is a retrospective study of patients with comorbid vulvar LS and HSIL treated with TCS between 2015 and 2020. Patients with clinically diagnosed or biopsy-proven LS and biopsy-proven HSIL of the vulva were included. Clinical data included demographics, tobacco use, immune-modifying conditions, specimen pathology, treatment types, and HSIL recurrence. Bivariate analysis was performed to compare demographic and clinical characteristics between patients with and without HSIL recurrence.

RESULTS

Twenty-six patients with comorbid LS and HSIL were identified. The median age was 66.0 years and median time in treatment for LS was 5.5 years. Thirteen (50%) had recurrence of HSIL and 13 (50%) did not have recurrence. Exposure to high-potency TCS was present in 20 (77%) patients, with 17 (65%) having use of more than 1-year duration and 9 (35%) having use at the time of HSIL diagnosis. When comparing the groups with and without HSIL recurrence, there was no significant difference in high-potency TCS exposure, duration of use, or use at time of HSIL diagnosis.

CONCLUSIONS

High-potency TCS use for the treatment of LS did not seem to increase the risk of HSIL recurrence in patients with comorbid vulvar LS and HSIL. This suggests that high-potency TCS can be appropriately used for the treatment of LS even when HPV-associated disease is present.

Squamous and Glandular Lesions of the Vulva and Vagina: What's New and What Remains Unanswered?

A number of changes have been introduced into the 5th Edition of the World Health Organization (WHO) Classification of squamous and glandular neoplasms of the vulva and vagina. This review highlights the major shifts in tumor classification, new entities that have been introduced, recommendations for p16 immunohistochemical testing, biomarker use, molecular findings and practical points for pathologists which will affect clinical care. It also touches upon several issues that still remain answered in these rare but undeniably important women's cancers.

Interobserver reproducibility of the diagnosis of differentiated exophytic vulvar intraepithelial lesion (DEVIL) and the distinction from its mimics

AIMS

Most vulvar squamous cell carcinomas are human papillomavirus (HPV)-associated or TP53-mutant. A third category of HPV-independent TP53-wild-type lesions is uncommon and not fully understood. Differentiated exophytic vulvar intraepithelial lesion (DEVIL) has been characterised as a precursor of this latter category. The reproducibility of the diagnosis of DEVIL and its distinction from lesions with overlapping morphology has not been studied. Our aim was to establish the interobserver agreement in the diagnosis of DEVIL and its distinction from neoplastic and reactive conditions of the vulva on haematoxylin and eosin evaluation.

METHODS AND RESULTS

A set of 35 slides was evaluated by eight reviewers (two trainees and six practising gynaecological pathologists). The set included DEVIL, condyloma, established vulvar precursors [high-grade squamous intraepithelial lesion (HSIL) and differentiated vulvar intraepithelial neoplasia (dVIN)] with superimposed acanthosis or verruciform growth, lichen simplex chronicus (LSC), and psoriasis. Kappa (κ) values were calculated. Overall, interobserver agreement was moderate (κ = 0.56), improving to substantial (κ = 0.7) when evaluation was performed by practising pathologists. Agreement was strong for the diagnosis of HSIL (κ = 0.88), and substantial for the diagnosis of DEVIL (κ = 0.61), condyloma (κ = 0.79), and LSC (κ = 0.72). Agreement was moderate for the diagnosis of dVIN (κ = 0.59) and psoriasis (κ = 0.53). Perfect agreement (6/6) among practising pathologists was observed in 43% of cases, and majority agreement (5/6 or 4/6) was observed in 48% of cases.

CONCLUSIONS

Reproducibility in the diagnosis of verruciform vulvar lesions, including the novel DEVIL, is acceptable overall. Reproducibility is higher for well-known lesions such as HSIL and condyloma than for more challenging diagnoses such as DEVIL, dVIN, and psoriasis. Agreement is higher among practising gynaecological pathologists, suggesting that training and experience improve reproducibility. Our findings support the inclusion of DEVIL as a diagnostic entity in the classification of vulvar squamous lesions.

Expanding the Morphologic, Immunohistochemical, and HPV Genotypic Features of High-grade Squamous Intraepithelial Lesions of the Vulva With Morphology Mimicking Differentiated Vulvar Intraepithelial Neoplasia and/or Lichen Sclerosus

Squamous cell carcinoma of the vulva can arise through 2 pathways: human papillomavirus (HPV)-dependent high-grade squamous intraepithelial lesions (previously termed usual vulvar intraepithelial neoplasia) or HPV-independent (differentiated vulvar intraepithelial neoplasia, dVIN). Distinguishing between the 2 types can be clinically and histologically difficult. A subset of high-grade squamous intraepithelial lesions with superimposed chronic inflammation mimicking dVIN has recently been reported; p53 shows characteristic mid-epithelial staining (with basal sparing) in such cases. The pathology databases of 2 academic institutions were searched for vulva specimens with corresponding p53 and p16 immunohistochemical stains, yielding 38 specimens (from 27 patients). In situ hybridization and multiplex polymerase chain reaction-MassArray for high-risk HPV were performed on at least 1 block from each patient. All cases resembled dVIN or lichen sclerosus morphologically, but with a higher degree of atypia. All but 1 case demonstrated mid-epithelial p53 staining with basal sparing by immunohistochemistry. All cases showed block positivity for p16 and at least patchy positivity by HPV in situ hybridization. Of the 23 cases with valid HPV DNA polymerase chain reaction results, 15 were positive and 8 were negative. Of the positive cases, HPV16 was identified in 10 cases, with other high-risk types in the remaining 5. To our knowledge, this is the largest cohort of high-grade squamous intraepithelial lesions mimicking dVIN reported to date. Prior studies reported positivity for HPV16 in all cases tested, however, we found HPV16 in only 67% of HPV positive cases. This case series highlights the importance of immunohistochemistry, and occasionally HPV in situ hybridization, for accurate diagnosis, and expands the spectrum of associated HPV types.

How Can We Treat Vulvar Carcinoma in Pregnancy? A Systematic Review of the Literature

According to our systematic literature review (PRISMA guidelines), only 37 vulvar squamous cell carcinomas (VSCCs) were diagnosed during pregnancy (age range: 17-41 years). The tumor size range was 0.3-15 cm. The treatment was performed after (14/37, 38%), before (10/37, 27%), or before-and-after delivery (11/37, 30%). We found that 21/37 (57%) cases were stage I, 2 II (5%), 11 III (30%), and 3 IVB (8%). HPV-related features (condylomas/warts; HPV infection; high-grade squamous intraepithelial lesion) were reported in 11/37 (30%) cases. We also found that 9/37 (24%) patients had inflammatory conditions (lichen sclerosus/planus, psoriasis, chronic dermatitis). The time-to-recurrence/progression (12/37, 32%) ranged from 0 to 36 (mean 9) months. Eight women died of disease (22%) 2.5-48 months after diagnosis, 2 (5%) were alive with disease, and 23 (62%) were disease-free at the end of follow-up. Pregnant patients must be followed-up. Even if they are small, newly arising vulvar lesions should be biopsied, especially in women with risk factors (HPV, dermatosis, etc.). The treatment of VSCCs diagnosed in late third trimester might be delayed until postpartum. Elective cesarean section may prevent vulvar wound dehiscence. In the few reported cases, pregnancy/fetal outcomes seemed to not be affected by invasive treatments during pregnancy. However, clinicians must be careful; larger cohorts should define the best treatment. Definite guidelines are lacking, so a multidisciplinary approach and discussion with patients are mandatory.

Molecular characterization of invasive and in situ squamous neoplasia of the vulva and implications for morphologic diagnosis and outcome

Human papillomavirus (HPV)-independent vulvar squamous cell carcinoma (VSCC) is an aggressive clinical entity. Current diagnostic guidelines for premalignant lesions are ambiguous, and their molecular profile and progression events are still unclear. We selected 75 samples, from 40 patients, including 33 VSCC, 8 verrucous carcinomas (VC), 13 differentiated-type vulvar intraepithelial neoplasia (dVIN), 11 suspicious for dVIN (?dVIN), 6 differentiated exophytic vulvar intraepithelial lesions (DE-VIL), 2 vulvar acanthosis with altered differentiation (VAAD), and 2 usual-type vulvar intraepithelial neoplasia (uVIN/HSIL). Invasive and precursor lesions were matched in 29 cases. Clinical information, p16 immunohistochemistry, and mutation analysis were performed on all lesions. All dVIN, ?dVIN, DE-VIL, and VAAD were p16 negative, all uVIN/HSIL were p16 positive. In the HPV-independent group, mutations were identified in 6 genes: TP53 (n = 40), PIK3CA (n = 20), HRAS (n = 12), MET (n = 5), PTEN (n = 4), and BRAF (n = 1). TP53 mutations occurred in 73% (22/30) VSCC, 85% (11/13) dVIN, 70% (7/10) ?dVIN and no VC (0/8), DE-VIL (0/6) nor VAAD (0/2). Basal atypia was the only reliable feature of TP53 mutations. ?dVIN lesions that were non-acanthotic and atypical but obscured by inflammation, all harbored TP53 mutations. In lesions without TP53 mutations, PIK3CA (50% VC, 33% DE-VIL, 100% VAAD, 40% VSCC) and HRAS (63% VC, 33% DE-VIL, 0% VAAD, 20% VSCC) mutations were found. Mutational progression from in situ to invasive was seen (7/26, 27%) and usually involved TP53 (4/26, 15%). Cases with TP53 and PIK3CA co-mutations had the worse clinical outcomes (p < 0.001). We recommend testing for p53 in all HPV-independent lesions suspicious for dVIN, even in the presence of marked inflammation or non-acanthotic skin, particularly when close to a margin. VC, VAAD, and DE-VIL, were almost never mutated for TP53, but instead often harbored PIK3CA and HRAS mutations. In VSCC, combined TP53 and PIK3CA mutations may inform prognosis.

Diagnostic Criteria for Differentiated Vulvar Intraepithelial Neoplasia and Vulvar Aberrant Maturation

OBJECTIVE

The aim of the study was to describe the features required for diagnosis of differentiated vulvar intraepithelial neoplasia (dVIN) and vulvar aberrant maturation (VAM).

MATERIALS AND METHODS

The International Society of the Study of Vulvovaginal Diseases tasked the difficult pathologic diagnoses committee to develop consensus recommendations for clinicopathologic diagnosis of vulvar lichen planus, lichen sclerosus, and dVIN. The dVIN subgroup reviewed the literature and formulated diagnostic criteria that were reviewed by the committee and then approved by the International Society of the Study of Vulvovaginal Diseases membership.

RESULTS

Differentiated vulvar intraepithelial neoplasia is the immediate precursor of human papillomavirus (HPV)-independent vulvar squamous cell carcinoma and shows a spectrum of clinical and microscopic appearances, some overlapping with HPV-related neoplasia. The histopathologic definition of dVIN is basal atypia combined with negative or nonblock-positive p16 and basal overexpressed, aberrant negative, or wild-type p53. The most common pattern of dVIN is keratinizing with acanthosis, aberrant rete ridge pattern, and premature maturation. The morphologic spectrum of keratinizing dVIN includes hypertrophic, atrophic, acantholytic, and subtle forms. A few dVIN cases are nonkeratinizing, with basaloid cells replacing more than 60% of epithelium. Vulvar aberrant maturation is an umbrella term for lesions with aberrant maturation that arise out of lichenoid dermatitis and lack the basal atypia required for dVIN.

CONCLUSIONS

Evaluation of women at risk for dVIN and VAM requires a collaborative approach by clinicians and pathologists experienced in vulvar disorders. Close surveillance of women with lichen sclerosus and use of these recommendations may assist in prevention of HPV-independent squamous cell carcinoma through detection and treatment of dVIN and VAM.

p53 Immunohistochemical Patterns in HPV-Independent Squamous Cell Carcinomas of the Vulva and the Associated Skin Lesions: A Study of 779 Cases

Human papillomavirus (HPV)-independent vulvar squamous cell carcinomas (VSCC) and its precursors frequently harbour TP53 mutations. Recently, six p53 immunohistochemical (IHC) patterns have been defined, which have shown strong correlation with TP53 mutation status. However, few studies have applied this new six-pattern framework and none of them exhaustively compared p53 IHC positivity and patterns between invasive VSCC and adjacent skin lesion. We performed p53 IHC in a series of 779 HPV-independent VSCC with adjacent skin and evaluated the IHC slides following the newly described classification. Some 74.1% invasive VSCC showed abnormal p53 IHC staining. A skin lesion was identified in 450 cases (57.8%), including 254 intraepithelial precursors and 196 inflammatory/reactive lesions. Two hundred and ten of 450 (47%) VSCC with associated skin lesions showed an abnormal p53 IHC stain, with an identical staining pattern between the VSCC and the adjacent skin lesion in 80% of the cases. A total of 144/450 (32%) VSCC showed wild-type p53 IHC both in the invasive VSCC and adjacent skin lesion. Finally, 96/450 (21%) VSCC showed p53 IHC abnormal staining in the invasive VSCC but a wild-type p53 staining in the skin lesion. Most of the discordant cases (70/96; 73%) showed adjacent inflammatory lesions. In conclusion, the p53 IHC staining and pattern are usually identical in the VSCC and the intraepithelial precursor.

Comparison of p53 immunohistochemical staining in differentiated vulvar intraepithelial neoplasia (dVIN) with that in inflammatory dermatoses and benign squamous lesions in the vulva

AIMS

Differentiated vulvar intraepithelial neoplasia (dVIN), the precursor lesion to human papillomavirus-independent vulvar squamous cell carcinoma (VSCC), can be difficult to distinguish from vulvar inflammatory dermatoses. Our goal was to determine if p53 could be a useful biomarker for dVIN, by characterizing p53 percentage, intensity and patterns of staining in dVIN and its histological mimics.

METHODS AND RESULTS

We studied p53 immunohistochemical staining patterns in 16 dVIN cases and 46 vulvar non-neoplastic squamous lesions [12 lichen sclerosus (LS); seven lichen simplex chronicus; three lichen planus (LP); six psoriasis; 13 spongiotic dermatitis (SPO); and five candidiasis]. dVIN cases were adjacent to a p16-negative invasive VSCC in resection specimens. All dVIN cases showed null-type or moderate to strong uniform p53 staining in >70% of basal cells, with moderate to strong continuous parabasal staining extending to two-thirds of the epidermis. This was in contrast to weak or weak to moderate patchy p53 staining in the majority of other lesions. Moderate to strong and increased basal p53 staining (≥70%) was also observed in a subset of LS cases (5/12, 42%), LP cases (1/3, 33%), and SPO cases (36%, 4/11); however, in all categories, this was limited to the basal layer, and any staining in the parabasal layers was patchy.

CONCLUSION

Strong and uniform p53 staining of basal cells, extending into the parabasal layers, and a complete absence of staining (null type) is useful in distinguishing dVIN from other mimics in the vulva. p53 staining of lesser intensity or quantity, particularly basal overexpression only, overlaps with that in vulvar inflammatory lesions.

Putative precancerous lesions of vulvar squamous cell carcinoma

Precursor lesions of vulvar squamous cell carcinoma (VSCC) can be divided into two major biologic and prognostic groups: HPV-associated and HPV-independent VSCC. These two pathways are categorized as usual vulvar intraepithelial neoplasia (uVIN) with progression to basaloid or warty VSCC and differentiated vulvar intraepithelial neoplasia (dVIN) with progression to the more common keratinizing VSCC. While the HPV-dependent pathway to squamous cell carcinoma is well-understood, the development of squamous cell carcinoma from HPV-independent lesions is less clear. The majority of HPV-independent lesions fall into the dVIN category, and mutations in TP53 have been implicated as the driver behind their development. Other less common HPV-independent precursor lesions, termed differentiated exophytic vulvar intraepithelial lesion (DEVIL) and vulvar acanthosis with altered differentiation (VAAD), have also been characterized as precursors to keratinizing and verrucous VSCC. Inflammatory conditions of the vulva such as lichen sclerosus and lichen simplex chronicus also put patients at risk for developing VSCC. We herein evaluate the available evidence and biologic basis for these VSCC precursor lesions, among other speculated entities, and discuss their clinical, diagnostic, and prognostic features.

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.

Major p53 immunohistochemical patterns in in situ and invasive squamous cell carcinomas of the vulva and correlation with TP53 mutation status

The recent literature has shown that vulvar squamous cell carcinoma (VSCC) can be stratified into two prognostically relevant groups based on human papillomavirus (HPV) status. The prognostic value of p53 for further sub-stratification, particularly in the HPV-independent group, has not been agreed upon. This disagreement is likely due to tremendous variations in p53 immunohistochemical (IHC) interpretation. To address this problem, we sought to compare p53 IHC patterns with TP53 mutation status. We studied 61 VSCC (48 conventional VSCC, 2 VSCC with sarcomatoid features, and 11 verrucous carcinomas) and 42 in situ lesions (30 differentiated vulvar intraepithelial neoplasia [dVIN], 9 differentiated exophytic vulvar intraepithelial lesions [deVIL], and 3 high-grade squamous intraepithelial lesions or usual vulvar intraepithelial neoplasia [HSIL/uVIN]). IHC for p16 and p53, and sequencing of TP53 exons 4-9 were performed. HPV in situ hybridization (ISH) was performed in selected cases. We identified six major p53 IHC patterns, two wild-type patterns: (1) scattered, (2) mid-epithelial expression (with basal sparing), and four mutant patterns: (3) basal overexpression, (4) parabasal/diffuse overexpression, (5) absent, and (6) cytoplasmic expression. These IHC patterns were consistent with TP53 mutation status in 58/61 (95%) VSCC and 39/42 (93%) in situ lesions. Cases that exhibited strong scattered staining and those with a weak basal overexpression pattern could be easily confused. The mid-epithelial pattern was exclusively observed in p16-positive lesions; the basal and parabasal layers that had absent p53 staining, appeared to correlate with the cells that were positive for HPV-ISH. This study describes a pattern-based p53 IHC interpretation framework, which can be utilized as a surrogate marker for TP53 mutational status in both VSCC and vulvar in situ lesions.

British Gynaecological Cancer Society (BGCS) vulval cancer guidelines: Recommendations for practice

The purpose of this guideline is to collate evidence and propose evidence-based guidelines for the diagnosis and management of adult patients with vulva carcinoma treated in the UK. Malignant melanoma may present via similar routes and will be discussed. The reader is referred to the Ano-uro-genital Mucosal Melanoma Full Guideline [1] for more detailed recommendations. The management of vulval sarcoma is outside of the scope of this guideline. For further information, including details of guideline development and GRADE of recommendations, please see BGCS website for details (https://www.bgcs.org.uk/professionals/guidelines-for-recent-publications/).

Performance of the pattern-based interpretation of p53 immunohistochemistry as a surrogate for TP53 mutations in vulvar squamous cell carcinoma

Aims

The most commonly mutated gene in vulvar squamous cell carcinoma (VSCC) is TP53 and its prognostic value, particularly in HPV‐independent VSCC, is uncertain. In other tumours, p53 immunohistochemistry (IHC) is an excellent surrogate marker for TP53 mutations. In order to study this in VSCC, we assigned six p53 IHC patterns into two final classes: ‘wild‐type’ or ‘mutant’. We determined the performance and interobserver variability of this pattern‐based p53 IHC approach.

Methods and results

Two experienced gynaecological pathologists scored the predefined p53 IHC patterns of 59 VSCC, independently and blinded for molecular data. Agreement was calculated by Cohen's kappa. All disagreements regarding p53 IHC patterns were resolved by a consensus meeting. After DNA isolation, the presence of pathogenic TP53 variants was determined by next‐generation sequencing (NGS). Sensitivity, specificity and accuracy of p53 IHC as a surrogate marker for TP53 mutation status were calculated. Initial p53 IHC pattern interpretation showed substantial agreement between both observers (k = 0.71, P < 0.001). After consensus, 18 cases (30.5%) were assigned a final p53 IHC class as TP53 wild‐type and 41 cases (69.5%) as mutant. The accuracy between the p53 IHC class and TP53 mutation status, after the consensus meeting, was 96.6%. Moreover, the sensitivity and specificity were high 95.3% [95% confidence interval (CI) = 82.9–99.1% and 100% (95% CI = 75.9–100%)].

Conclusions

Pattern‐based p53 IHC classification is highly reproducible among experienced gynaecological pathologists and accurately reflects TP53 mutations in VSCC. This approach to p53 IHC interpretation offers guidance and provides necessary clarity for resolving the proposed prognostic relevance of final p53 IHC class within HPV‐independent VSCC.

A Comprehensive Review of Biomarker Use in the Gynecologic Tract Including Differential Diagnoses and Diagnostic Pitfalls

Morphologic (ie, hematoxylin and eosin) evaluation of the Mullerian tract remains the gold standard for diagnostic evaluation; nevertheless, ancillary/biomarker studies are increasingly utilized in daily practice to assist in the subclassification of gynecologic lesions and tumors. The most frequently utilized "biomarker" technique is immunohistochemistry; however, in situ hybridization (chromogenic and fluorescence), chromosomal evaluation, and molecular analysis can also be utilized to aid in diagnosis. This review focuses on the use of immunohistochemistry in the Mullerian tract, and discusses common antibody panels, sensitivity and specificity of specific antibodies, and points out potential diagnostic pitfalls when using such antibodies.

Precursor lesions of vulvar squamous cell carcinoma - histology and biomarkers: A systematic review

The precursor lesion of vulvar squamous cell carcinoma (VSCC), namely vulvar intraepithelial neoplasia (VIN), is classified as: human papillomavirus (HPV)-related high grade squamous intraepithelial lesion (HSIL), and HPV-independent differentiated VIN (dVIN). Traditionally, histology and immunohistochemistry (IHC) have been the basis of diagnosis and classification of VIN. HSIL shows conspicuous histological atypia, and positivity on p16-IHC, whereas dVIN shows less obvious histological atypia, and overexpression or null-pattern on p53-IHC. For both types of VIN, other diagnostic immunohistochemical markers have also been evaluated. Molecular characterization of VIN has been attempted in few recent studies, and novel genotypic subtypes of HPV-independent VSCC and VIN have been identified. This systematic review appraises the VSCC precursors identified so far, focusing on histology and biomarkers (immunohistochemical and molecular). To gain further insights into the carcinogenesis and to identify additional potential biomarkers, gene expression omnibus (GEO) datasets on VSCC were analyzed; the results are presented.

New Directions in Vulvar Cancer Pathology

PURPOSE OF REVIEW

The aim of this article is to provide clinicians and pathologists with an understanding of the aetiopathology, pathogenesis and classification of vulval neoplasia and their molecular correlates.

RECENT FINDINGS

There is an increased understanding of subcellular changes in vulvar malignancies. These provide the direction for further research and aid personalised treatment for patients. The article explores concepts of the aetiology of vulvar cancer and updates the reader with the equivalence of terminology of preneoplastic vulval disease. The differential diagnosis of squamous neoplasia and their clinicopathological correlation is detailed. The salient findings from recent literature into the understanding of the disease of squamous cell neoplasia and rare vulvar malignancies are summarised.