Lynn Hoang

Prognostic values of molecular subtypes and SWI/SNF protein expression in de‐differentiated/undifferentiated endometrial carcinoma

AimsClassification and risk stratification of endometrial carcinoma (EC) has transitioned from histopathological features to molecular classification, e.g. the ProMisE classifier, identifying four prognostic subtypes: POLE mutant (POLEmut) with almost no recurrence or disease‐specific death events, mismatch repair deficient (MMRd) and no specific molecular profile (NSMP), with intermediate outcome and p53 abnormal (p53abn) with poor outcomes. However, the applicability of molecular classification is unclear in rare but aggressive histotypes of EC, e.g. de‐differentiated and undifferentiated endometrial cancers (DD/UDEC). Here, we aim to assembled a cohort of DD/UDEC from a single institution and analysed the prognostic significance of ProMisE molecular subtypes and the expression of SWItch/sucrose non‐fermentable (SWI/SNF) chromatin remodelling complex members, previously implicated in the pathogenesis of DD/UDEC.Methods and resultsWe accrued 88 DD/UDEC cases, assessed POLE status by Sanger sequencing and performed immunohistochemistry for p53, mismatch repair and SWI/SNF proteins on the tissue microarrays assembled. Assignment of molecular subtypes was possible in 80 tumours; POLE sequencing failed in the remaining eight cases. There were 12 (15%) POLEmut, 44 (55%) MMRd, 14 (17.5%) p53abn and 10 (12.5%) NSMP DD/UDEC. POLEmut DD/UDECs had excellent outcomes, but the other three molecular subtypes all had poor outcomes, with no significant differences among them. The loss of one or more SWI/SNF proteins [AT‐rich interactive domain‐containing protein 1A (ARID1A), ARID1B, SWI/SNF‐related, matrix‐associated, actin‐dependent regulator of chromatin, subfamily A, member 4 (SMARCA4), SMARCA2], observed in 66% (55 of 83) cases, was not of prognostic significance.ConclusionsThese results indicate that all molecular subtypes of DD/UDEC except POLEmut behave in an aggressive fashion. Further study is needed to determine whether these molecular alterations can be targeted with adjuvant therapy, in order to improve outcomes of patients with DD/UDEC.

Papillary and ductal patterns of mesonephric‐like adenocarcinomas are often overlooked: a retrospective revaluation of over 1000 endometrial carcinomas

AimsMesonephric‐like adenocarcinoma (MLA) of the endometrium is often a diagnostic challenge, due to its morphological resemblance to other more common Müllerian neoplasms. This study aimed to retrospectively identify overlooked MLA in a large endometrial carcinoma cohort, using a combination of immunohistochemistry (IHC), morphology and KRAS sequencing.Methods and resultsIHC was conducted on 1094 endometrial carcinomas, identifying 16 potential MLA cases based on GATA3+ and/or TTF1+ and ER− staining patterns, which subsequently underwent detailed histological review, KRAS sequencing and ProMisE molecular classification. Of the IHC screen‐positive cases, one was positive for both GATA3 and TTF1, nine were positive for GATA3 only and six were positive for TTF1 only. All IHC screen‐positive cases were POLE wild‐type. All five tumours in the NSMP category showed morphological features of MLA, while the three MMRd and eight p53abn tumours did not show MLA morphology. The five cases diagnosed as MLA on review were all originally diagnosed as low‐grade endometrioid adenocarcinoma probably because of rare morphological patterns, being predominantly papillary or ductal. Four of the five cases harboured a KRAS mutation.ConclusionThis study highlights the importance of a comprehensive diagnostic approach for accurately identifying endometrial MLA and for pathologists to be aware of papillary and ductal patterns in endometrial carcinoma assessment. Further exploration into the molecular landscape of MLA is essential for refining diagnostic criteria and developing targeted therapies.

The spectrum of oestrogen receptor expression in endometrial carcinomas of no specific molecular profile

AimsDecreased oestrogen receptor (ER) expression is a marker of poor prognosis in endometrial carcinomas (EC) of no specific molecular profile (NSMP), but the optimal cut‐off to separate high‐risk ‘low ER’ versus low‐risk ‘high ER’ expression has not been defined. Here we characterised the distribution of ER staining in a cohort of ECs.Methods and resultsBiopsy specimens from 120 cases of NSMP EC were stained for ER and assigned an Allred score. In 66 additional cases ER staining of matched biopsy and hysterectomy were compared. Twelve of 120 tumours had an Allred score of 0–3, including three endometrioid carcinomas (EEA) (one G1, two G3), four clear cell carcinomas (CCC), two mesonephric‐like adenocarcinoma (MLA) and one each of: gastric‐type adenocarcinoma, carcinosarcoma and endometrial carcinoma NOS. Three had Allred scores of 4–5: two MLA and one high‐grade carcinoma with yolk sac differentiation. Five had Allred scores of 6: four EEA (one G1, one G2, two G3) and one mixed clear cell and endometrioid carcinoma. The remaining 100 tumours with Allred scores ≥ 7 were all EEA (66 G1, 28 G2, five G3 and one grade unknown). Comparing the biopsy versus hysterectomy ER staining (n = 66), the results were within a single Allred score point, except two cases with strong diffuse expression in the biopsy (Allred 8) and moderate expression in the hysterectomy (Allred 5).ConclusionsMost NSMP ECs (> 80%) show high ER expression (Allred score ≥ 7). All non‐endometrioid carcinomas and a few endometrioid carcinomas had lower ER expression (Allred score ≤ 6) or were completely negative.

Proficiency Testing of p53 Immunohistochemistry Pattern Read-out in Vulvar Biopsies Demonstrates Frequent Basal Overexpression Interpretation in TP53 Wild-type Cases

Recently, criteria for p53 immunohistochemistry (IHC) interpretation were described in squamous neoplasia of the vulva. This pattern-based approach detailed 2 wild-type patterns (scattered and basal-sparing) and 4 mutant patterns (parabasal/diffuse overexpression, basal overexpression, null, and cytoplasmic). However, the proficiency of pathologist read-out has not been studied. We created an online tool to evaluate p53 IHC interpretation proficiency. p53 IHC on 90 vulvar biopsies (n=31 squamous in situ/premalignant and n=59 benign lesions) were scanned (without corresponding H&E). Fifteen pathologists assessed 45 cases in Module A and assigned each case as wild-type or mutant via the 6 p53 IHC patterns. Following Module A, participants were given the suggested p53 IHC pattern and TP53 sequencing data for each case. After self-review, pathologists completed a second 45 case set (Module B). The average pathologist score per case increased from Module A to Module B (69.8%–87.7%, P=0.0005). Pathologist proficiency was excellent in the parabasal/diffuse (100%–100%), null (93.3%–90.0%), and basal-sparing (88.9%–100%) patterns. The greatest discrepancy was due to the interpretation of the basal overexpression pattern in cases that were TP53 wild-type by sequencing, but this improved with educational intervention. Scores for the scattered pattern improved from 64.9% to 82.8% and basal overexpression from 73.3% to 91.1% after completion of the training module. Pathologists should exhibit caution when interpreting p53 IHC as basal overexpression, as this pattern can be seen in the absence of TP53 alterations. There were 2 cases with convincing p53 IHC abnormal patterns (1 parabasal/diffuse and 1 null) without TP53 mutations by sequencing.

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.

p53-Abnormal “Fields of Dysplasia” in Human Papillomavirus–Independent Vulvar Squamous Cell Carcinoma Impacts Margins and Recurrence Risk

Abnormal p53 (p53abn) immunohistochemical (IHC) staining patterns can be found in vulvar squamous cell carcinoma (VSCC) and differentiated vulvar intraepithelial neoplasia (dVIN). They can also be found in the adjacent skin that shows morphology that falls short of the traditional diagnostic threshold for dVIN. Vulvectomy specimens containing human papillomavirus-independent p53abn VSCC with margins originally reported as negative for invasive and in situ disease were identified. Sections showing the closest approach by invasive or in situ neoplasia to margins were stained with p53 IHC stains. We evaluated the following: (1) detection of morphologically occult p53abn in situ neoplasia, (2) rates of margin status change after p53 IHC staining, and (3) effect of p53abn IHC staining at margins on the 2-year local recurrence rates. Seventy-three human papillomavirus-independent p53abn VSCCs were included. Half (35/73, 48%) had documented an in situ lesion in the original report. The use of p53 IHC staining identified 21 additional cases (29%) with the p53abn in situ lesions that were originally unrecognized. The histology of in situ lesions in the p53abn "field" varied and became more subtle (morphologically occult) farther away from the VSCC. Fifteen (21%) cases had a morphologically occult and previously unrecognized p53abn in situ lesion present at a resection margin, which conferred an increased risk of local recurrence (5/7 [71.4%] vs 6/22 [27.3%], P = .036). The p53abn in situ lesions at a margin were confirmed to have TP53 mutations by sequencing. p53 IHC staining identified morphologically occult p53abn in situ lesions surrounding human papillomavirus-independent VSCC. p53abn IHC staining at a margin was associated with a 3-fold increased risk of local recurrence.

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

AimsDifferentiated 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 resultsWe 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.ConclusionStrong 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.

Bridging historical evidence and contemporary strategies in the adjuvant treatment of early-stage epithelial ovarian cancer

The umbrella term "epithelial ovarian cancer" encompasses 5 histologic sub-types with distinct molecular profiles and varying sensitivities to chemotherapy. Historical trials investigating adjuvant management of early-stage disease have not accounted for this heterogeneity. This review examines the evidence guiding the management of stage I and II epithelial ovarian cancer according to histologic sub-type and discusses its application in contemporary modern setting. Areas of interest for future research are highlighted, with an emphasis on the need for more personalized adjuvant therapy using predictive biomarkers and targeted treatments.