Folate Receptor Immunohistochemical Staining and Gynecologic Tumors: Initial Experience With 216 Cases.

Folate receptor alpha has been shown to have possible mechanisms of tumorigenesis in malignancies, becoming a potential target for therapy. Mirvetuximab soravtansine is an antifolate receptor alpha monoclonal antibody, with an approved FOLR1-2.1 immunohistochemical biomarker. After IRB approval, a retrospective review of gynecologic pathology cases was performed to identify cases in which FOLR1 immunohistochemistry (IHC) was performed at our institution over a period of 9 months as part of clinical care for therapy eligibility. Clinical data collected included patients' age, tumor histotype, tumor grade, primary tumor site, FIGO stage, dates of recurrence/progression, and use of mirvetuximab therapy. FOLR1 IHC data were recorded, including the date specimen obtained, date IHC was performed, site tested, case type, percentage tumor staining, and intensity. Cases were deemed positive or negative according to current recommendations (75%, 2-3+intensity). Two hundred sixteen cases were identified. Patient ages ranged from 25 to 83 years old (median: 59 yr). Staining intensity was reported as 0 in 15 (6.9%) cases, weak (1+) in 8 (3.7%), moderate (2+) in 27 (12.5%), strong (3+) in 27 (12.5%), weak-to-moderate (1-2+) in 15 (6.9%), and moderate-to-strong (2-3+) in 99 (45.8%); intensity was not provided in 25 (11.6%). Percentage of tumor staining ranged from 0 to 100, with a median of 60. The IHC was overall deemed positive in 98 (45.4%) cases and negative in 118 (54.6%). By histotype, 5 of 17 (29.4%) low-grade serous carcinomas, 88 of 162 (54.3%) high-grade serous carcinomas, 3 of 5 (60%) of carcinosarcomas, and 2 of 6 (33.3%) of mixed carcinomas were positive. No case of clear cell CA, endometrioid CA, Mullerian CA NOS, serous borderline, mucinous CA, or granulosa cell tumor was positive. The primary site of disease was tubo-ovarian in 192 (88.9%) cases, peritoneal in 8 (3.7%) cases, uterine in 3 (1.4%) cases, and unknown in 13 (6%) cases. By site on which immunohistochemical stain was performed: primary site positive in 53 of 96 (55.2%) cases, metastatic site at time of diagnosis/debulking positive in 23 of 41 (52.1%) cases, and metastatic/recurrent cases positive in 22 of 79 (27.8%) cases. There was a statistically significant correlation when comparing the positivity rates between these sites (P = 0.0004). Survival data were examined with high-grade serous carcinoma, with no statistically significant difference between positive and negative cases in overall survival (P = 0.622) or progression-free survival (P = 0.711). Biopsy specimens were positive in 17 (25%) cases, while negative in 51 (75%), whereas resection specimens were positive in 81 (54.7%) and negative in 67 (45.3%), a statistically significant difference (P < 0.0001). Cases that were <19 months old had 38 (36.2%) positive and 67 (63.8%) negative, compared with cases ≥19 months old that had 60 (54.1%) positive and 51 (45.9%) negative, a statistically significant difference (P = 0.0084). Significant differences in FOLR1 staining were noted between histotypes, age of the specimen, type of case tested, and site of disease tested. Further testing is needed to help determine the best tissue to be utilized for this new biomarker.

Extrauterine Mesonephric-like Carcinoma: A Comprehensive Single Institution Study of 33 Cases.

Extrauterine mesonephric-like carcinoma (ExUMLC) shares histologic, immunohistochemical (IHC), and molecular (MOL) features with endometrial mesonephric-like carcinoma (EnMLC). Its rarity and histologic overlap with Mullerian carcinomas contribute to underrecognition of ExUMLC. Aggressive behavior of EnMLC is well-documented; behavior of ExUMLC is yet to be characterized. This study presents the clinicopathologic, IHC, and MOL features of 33 ExUMLC identified over a 20-year time period (2002-2022) and compares the behavior of this cohort to more common upper gynecologic Mullerian carcinomas (low-grade endometrioid, LGEC; clear cell, CCC; high-grade serous, HGSC) and EnMLC diagnosed over the same time period. ExUMLC patients ranged from 37 to 74 years old (median=59 y); 13 presented with advanced stage (FIGO III/IV) disease. Most ExUMLC had the characteristic mixture of architectural patterns and cytologic features, as previously described. Two ExUMLC had sarcomatous differentiation, 1 with heterologous rhabdomyosarcoma. Twenty-one ExUMLC (63%) had associated endometriosis, and 7 (21%) arose in a borderline tumor. In 14 (42%) cases, ExUMLC was part of a mixed carcinoma representing >50% of the tumor in 12. Twenty-six cases (79%) were incorrectly classified as follows: LGEC or HGEC (12); adenocarcinoma, not otherwise specified (3); HGSC (3); LGSC (2); mixed carcinoma (1); carcinosarcoma, Mullerian type (2); seromucinous carcinoma (1); transitional pattern of HGSC (1); and female adnexal tumor of probable Wolffian origin (1). Three patients had occult synchronous endometrial LGEC. IHC facilitated diagnosis in all cases with an expression of GATA-3 and/or TTF-1 in conjunction with decreased hormone receptor expression in most tumors. MOL testing (n=20) identified a variety of mutations, most frequently: KRAS (15); TP53 (4); SPOP (4); and PIK3CA (4). ExUMLC and CCC were more likely to be associated with endometriosis ( P <0.0001). ExUMLC and HGSC had more recurrences compared with CCC and LGEC ( P <0.0001). Histologic subtype was associated with longer disease-free survival for LGEC and CCC versus HGSC and ExUMLC ( P <0.001). ExUMLC trended towards a similar poor overall survival as HGSC compared with LGEC and CCC, and EnMLC trended to shorter survival compared with ExUMLC. Neither finding reached significance. No differences were seen between EnMLC and ExUMLC with respect to presenting stage or recurrence. Staging, histotype, and endometriosis were associated with disease-free survival, but on multivariate analysis, only stage remained as an independent predictor of outcome. The tendency of ExUMLC to present at an advanced stage and have distant recurrence points to more aggressive behavior compared with LGEC with which it is most frequently confused, underscoring the importance of an accurate diagnosis.

SOX17: A Highly Sensitive and Specific Immunomarker for Ovarian and Endometrial Carcinomas.

PAX8 is the most commonly used immunomarker to link a carcinoma to the gynecologic tract; however, it lacks specificity. Through mining The Cancer Genome Atlas mRNA expression profile data, we identified SOX17 as a potential specific marker at the mRNA level for gynecologic tumors. To evaluate the utility of this marker in the identification of the gynecologic origin of a given carcinoma, we performed immunochemical staining in a large cohort of ovarian and endometrial cancer cases (n = 416), together with a large cohort of solid tumors from other organs (n = 1544) in tissue microarrays. Similar to PAX8, SOX17 was highly expressed in different subtypes of ovarian carcinoma (97.5% for SOX17 vs 97% for PAX8 in serous carcinoma, 90% vs 90% in endometrioid carcinoma, and 100% vs 100% in clear cell carcinoma), except for mucinous carcinoma (0% vs 27%), and was also highly expressed in different subtypes of endometrial carcinoma (88% vs 84% in endometrioid carcinoma, 100% vs 100% in serous and clear cell carcinoma). SOX17 was not expressed in thyroid and renal cell carcinomas, whereas PAX8 expression was high (86% and 85%, respectively). In addition, SOX17 was expressed at low levels in cervical adenocarcinoma (20%) and had no expression in cervical squamous carcinoma, mesothelioma, and carcinomas from the breast, lung, pancreas, colon, stomach, liver, bladder, and salivary gland. Our data indicate that SOX17 is not only a sensitive but also a specific marker for the origin of ovarian and endometrial carcinomas.

Peritoneal Mesothelioma-An Update.

A remarkable amount of new information has been generated on peritoneal mesothelioma (PeM), ranging from nomenclature changes, including the removal of "malignant" when referring to this neoplasm and the use of the term "tumor" rather than "mesothelioma" to designate the neoplasm formerly known as "well-differentiated papillary mesothelioma", to the acknowledgment that PeMs can be associated with tumor predisposition syndromes or germline mutations. Although the disease is still more frequently seen in caucasian males, PeM is not uncommon in women. In addition, it can represent a diagnostic challenge when it has an uncommon presentation (ie, paraneoplastic syndrome or incidental finding) or when it has confounding histologic features. Ancillary testing, including immunohistochemical stains, in situ hybridization for CDKN2A or NF2 , and molecular studies, in selected cases, allows its correct diagnosis. The molecular landscape of PeM is still a work in progress; however, some findings, such as ALK gene rearrangements and EWSR1/FUS-ATF1 fusions, are specifically seen in PeM of young patients. The biological behavior of PeM is variable; however, cytoreductive surgery and hyperthermic intraperitoneal chemotherapy have markedly improved the survival of patients affected by this disease.

Integrated multi-omic analysis of low-grade ovarian serous carcinoma collected from short and long-term survivors.

BACKGROUND: Low-grade serous ovarian cancer (LGSOC) is a rare disease that occurs more frequently in younger women than those with high-grade disease. The current treatment is suboptimal and a better understanding of the molecular pathogenesis of this disease is required. In this study, we compared the proteogenomic analyses of LGSOCs from short- and long-term survivors (defined as < 40 and > 60 months, respectively). Our goal was to identify novel mutations, proteins, and mRNA transcripts that are dysregulated in LGSOC, particularly in short-term survivors. METHODS: Initially, targeted sequencing of 409 cancer-related genes was performed on 22 LGSOC and 6 serous borderline ovarian tumor samples. Subsequently, whole-genome sequencing analysis was performed on 14 LGSOC samples (7 long-term survivors and 7 short-term survivors) with matched normal tissue samples. RNA sequencing (RNA-seq), quantitative proteomics, and phosphoproteomic analyses were also performed. RESULTS: We identified single-nucleotide variants (SNVs) (range: 5688-14,833 per sample), insertion and deletion variants (indels) (range: 880-1065), and regions with copy number variants (CNVs) (range: 62-335) among the 14 LGSOC samples. Among all SNVs and indels, 2637 mutation sites were found in the exonic regions. The allele frequencies of the detected variants were low (median12%). The identified recurrent nonsynonymous missense mutations included KRAS, NRAS, EIF1AX, UBR5, and DNM3 mutations. Mutations in DNM3 and UBR5 have not previously been reported in LGSOC. For the two samples, somatic DNM3 nonsynonymous missense mutations in the exonic region were validated using Sanger sequencing. The third sample contained two missense mutations in the intronic region of DNM3, leading to a frameshift mutation detected in RNA transcripts in the RNA-seq data. Among the 14 LGSOC samples, 7754 proteins and 9733 phosphosites were detected by global proteomic analysis. Some of these proteins and signaling pathways, such as BST1, TBXAS1, MPEG1, HBA1, and phosphorylated ASAP1, are potential therapeutic targets. CONCLUSIONS: This is the first study to use whole-genome sequencing to detect somatic mutations in LGSOCs with matched normal tissues. We detected and validated novel mutations in DNM3, which were present in 3 of the 14 samples analyzed. Additionally, we identified novel indels, regions with CNVs, dysregulated mRNA, dysregulated proteins, and phosphosites that are more prevalent in short-term survivors. This integrated proteogenomic analysis can guide research into the pathogenesis and treatment of LGSOC.

Data Set for the Reporting of Ovarian, Fallopian Tube and Primary Peritoneal Carcinoma: Recommendations From the International Collaboration on Cancer Reporting (ICCR).

The move toward consistent and comprehensive surgical pathology reports for cancer resection specimens has been a key development in supporting evidence-based patient management and consistent cancer staging. The International Collaboration on Cancer Reporting (ICCR) previously developed a data set for reporting of the ovarian, fallopian tube and primary peritoneal carcinomas which was published in 2015. In this paper, we provide an update on this data set, as a second edition, that reflects changes in the 2020 World Health Organization (WHO) Classification of Female Genital Tumours as well as some other minor modifications. The data set has been developed by a panel of internationally recognized expert pathologists and a clinician and consists of "core" and "noncore" elements to be included in surgical pathology reports, with detailed commentary to guide users, including references. This data set replaces the widely used first edition, and will facilitate consistent and accurate case reporting, data collection for quality assurance and research, and allow for comparison of epidemiological and pathologic parameters between different populations.

Contemporary primary treatment of women with stage II-IV low-grade serous ovarian/peritoneal cancer (LGSOC): Determinants of relapse and disease-free survival.

OBJECTIVE: The purpose of the present study is to describe a cohort who received contemporary primary treatment for stage II-IV low-grade serous ovarian/peritoneal cancer (LGSOC), including patient characteristics and determinants of relapse and disease-free survival. METHODS: The study included 99 patients: 1) with pathologically confirmed stage II-IV LGSOC of the ovary or peritoneum, 2) who underwent primary treatment consisting of cytoreductive surgery and either a) platinum/taxane chemotherapy followed by aromatase inhibitor maintenance therapy or b) aromatase inhibitor monotherapy, and 3) for whom there was availability of clinical data. Descriptive statistics were used to characterize clinicodemographic features. Subgroups were compared for PFS and OS. Multivariable Cox regression analyses were performed. RESULTS: Median PFS for the entire cohort was 56.8 months (95% CI, 41.3-NE), and median OS was 130.7 months (95% CI, 115.0-146.4). Forty-nine of 99 (49.5%) patients have relapsed to date. For these 49 patients, median time from diagnosis to relapse was 29.6 months (95% CI, 24.6-33.1) (range, 5.4-69.1 months). Only 1/49 (2%) patients who relapsed did so >5 years from diagnosis. Fifty (50.0%) patients have not experienced disease progression or relapse. Median follow-up time for these 50 patients is 86.2 months (range, 25.3-169.0). Thirty-three of the 50 (66.0%) have been followed for >5 years from diagnosis. On regression analyses, factors associated with improved patient outcomes-either PFS, OS, or both-included no gross residual disease, normal serum CA 125 at diagnosis, primary peritoneal site, and presence of extensive psammomatous calcifications. CONCLUSIONS: This is the first report to describe the clinicopathologic features and outcomes of women with stage II-IV LGSOC who received contemporary primary therapy.

Localized Malignant Peritoneal Mesothelioma (LMPeM) in Women: A Clinicopathologic Study of 18 Cases.

Localized malignant peritoneal mesothelioma is a rare tumor with limited information in the literature. In this study, we present our experience with 18 cases seen in our hospital over a period of 43 years (1978 to 2021). Patients' median age was 55 years (y) (range: 33 to 79 y) and most of them were Caucasians. Patients presented with abdominal pain (11), ascites and right leg swelling (1), abdominal mass (1), and as incidental finding (1). Thirty percent of patients reported asbestos exposure, and all patients with available information had family history of tumors; a third had personal history of tumors. Seventy-seven percent had some form of abdominopelvic surgery and/or inflammatory process. Most cases had microscopic features typically seen in malignant mesothelioma; however, some cases had confounding features such as signet-ring cells, spindle cells, clear cell changes, and adenomatoid tumor-like appearance. BAP-1 by immunohistochemistry was lost in 1/3 cases. Only 1 patient underwent genetic testing and had an MSH2 germline mutation. Homozygous deletion of CDKN2A by FISH was not found in 1 tested case, although next-generation sequencing identified a CDKN2A pathogenic mutation. 16/18 (88%) had surgical treatment, and some also received adjuvant chemotherapy. The mean overall survival (OS) of our patients was 80.4 months (95% confidence interval: 54.3-106.52); the 3-year OS was 79%, while the 5-year OS was 52.6%. Fifty-three percent of patients had recurrences and 20% had tumor progression. Although the limited sample precludes definitive conclusions, small tumor size, low-grade cytology, and low mitotic index appeared to be associated with an indolent behavior.

The genomic landscape of low-grade serous ovarian/peritoneal carcinoma and its impact on clinical outcomes.

OBJECTIVE: Low-grade serous carcinoma (LGSOC) is a rare epithelial ovarian/peritoneal cancer characterized by younger age at diagnosis, relative chemoresistance, prolonged overall survival (OS), and mutations in the mitogen activated protein kinase (MAPK) pathway compared to high-grade serous carcinoma. We describe the genomic profile of LGSOC by next generation sequencing (NGS) and evaluated its potential relationship to clinical outcomes. METHODS: The study included 215 women with LGSOC with: 1) pathologically confirmed LGSOC, 2) availability of NGS data, and 3) adequate clinical data. Clinical subgroups were compared for progression-free survival (PFS) and OS. Multivariable Cox regression analysis was performed. RESULTS: Median age at diagnosis was 46.6 years. The majority had a stage III ovarian primary. One or more mutations were identified in 140 (65.1%) cases; 75 (34.9%) had none. The most common mutations were KRAS (n = 71; 33.0%), NRAS (n = 24; 11.2%), and BRAF (n = 18; 8.4%). Patients with MAPK-mutated tumors (n = 113) (52.6%) had a significantly longer OS compared to those with tumors lacking MAPK pathway mutations (n = 102) (47.4%) [median OS, 147.8 months (95% CI,119.0-176.6) versus 89.5 months (95% CI, 61.4-117.7) (p = 0.01)], respectively. Median OS for patients with MAPK-mutated tumors was also significantly better than for patients whose tumors had no mutations (n = 75) [median OS, 147.8 months (95% CI, 119.0-176.6) versus 78.0 months (95% CI, 57.6-98.3)], respectively (p = 0.001). Median OS for patients with non-MAPK-mutated tumors (n = 27) was 125.1 months (95% CI, 83.9-166.3). In multivariable analysis, having a MAPK mutation was associated with improved OS. CONCLUSIONS: Patients with MAPK-mutated tumors have a significantly improved OS compared to those without MAPK-mutated tumors.

Precursors in the ovarian stroma: another pathway to explain the origin of ovarian serous neoplasms.

Ovarian serous neoplasms are thought to arise from the fallopian tube or from the ovarian surface epithelium. The possibility of a third pathway-involving the mesenchymal-epithelial transition and mimicking the formation of the Müllerian duct-arose from observations gathered from our routine cases. The purpose of this study is to determine the association of precursors in the ovarian stroma with different types of ovarian serous neoplasms. Three hundred neoplasms, benign (25), borderline (63), and malignant ovarian serous neoplasms (40 low-grade serous carcinomas [LGSCas] and 172 high-grade serous carcinomas [HGSCas]), were reviewed. Clinicopathologic features analyzed included patient's age, tumor size, stage, histologic pattern, and possible precursors in the ovarian parenchyma (endosalpingiosis, inverted macropapillae, polyploid giant cancer cells, and simple cysts). All benign and borderline cases showed continuity with benign serous cysts or endosalpingiosis. In LGSCas, continuity with serous cysts was found in 29 (72%) of 40 cases, and inverted macropapillae were found in 12 (30%) of 40 cases. In untreated HGSCas, there was continuity with simple cysts in 42% of cases. In addition, these HGSCas contained polyploid giant cancer cells in 20% of cases. There were no different features in the ovaries in cases with or without serous tubal intraepithelial carcinoma. Our study shows that in a subset of cases, ovarian serous neoplasms and the Müllerian duct develop in similar fashion, originating from epithelial cells derived from the mesothelium, or occur de novo from structures derived from mesenchymal-epithelial transition.

Integrated Analysis of Ovarian Juvenile Granulosa Cell Tumors Reveals Distinct Epigenetic Signatures and Recurrent TERT Rearrangements.

PURPOSE: Adult granulosa cell tumor (AGCT) is characterized by the somatic FOXL2 p.C134W mutation, and recurrences have been associated with TERT promoter and KMT2D-truncating mutations. Conversely, the molecular underpinnings of the rare juvenile granulosa cell tumor (JGCT) have not been well elucidated. To this end, we applied a tumor-only integrated approach to investigate the genomic, transcriptomic, and epigenomic landscape of 31 JGCTs to identify putative oncogenic drivers. EXPERIMENTAL DESIGN: Multipronged analyses of 31 JGCTs were performed utilizing a clinically validated next-generation sequencing (NGS) panel targeting 580 cancer-related genes for genomic interrogation, in addition to targeted RNA NGS for transcriptomic exploration. Genome-wide DNA methylation profiling was conducted using an Infinium Methylation EPIC array targeting 866,562 CpG methylation sites. RESULTS: We identified frequent KMT2C-truncating mutations along with other mutated genes implicated in the switch/sucrose nonfermentable (SWI/SNF) chromatin remodeling complex, in addition to previously reported hotspot AKT1 and DICER1 mutations. Targeted transcriptome sequencing revealed recurrent TERT rearrangements (13%) involving partners CLPTM1L or DROSHA, and differential gene expression analysis showed FGFR1 upregulation in the TERT non-rearranged JGCTs under direct promoter control. Genome-wide DNA methylation rendered a clear delineation between AGCTs and JGCTs at the epigenomic level, further supporting its diagnostic utility in distinguishing among these tumors. CONCLUSIONS: This is the largest comprehensive molecular study of JGCTs, where we further expand our current understanding of JGCT pathogenesis and demonstrate putative oncogenic drivers and TERT rearrangements in a subset of tumors. Our findings further offer insights into possible targeted therapies in a rare entity.

Uterine Inflammatory Myofibroblastic Neoplasms With Aggressive Behavior, Including an Epithelioid Inflammatory Myofibroblastic Sarcoma: A Clinicopathologic Study of 9 Cases.

The experience with uterine inflammatory myofibroblastic neoplasms with an unfavorable outcome is limited. We present the clinicopathologic features of 9 such cases, including 8 inflammatory myofibroblastic tumors (IMTs) and 1 epithelioid inflammatory myofibroblastic sarcoma (EIMS). Median patient age for the IMT group was 50.5 years; the patient with EIMS was 43 years old. Patients presented with abnormal uterine bleeding, presumed fibroids, pelvic pain, arthralgia and low-grade fever, as well as an incidental finding. Median tumor size for the IMTs was 8.5 cm. The borders were either infiltrative or well-circumscribed. Histologically, IMTs were purely fascicular or myxoid or showed predominance of one or the other pattern. Seven tumors were spindled, and 1 was both spindled and epithelioid. Tumors had variable nuclear atypia, ranging from grade 1 to 3. All tumors had an inflammatory infiltrate-predominantly lymphocytic, majority had necrosis (62.5%) and none had lymphovascular invasion. 7/8 (87.5%) tumors were positive for ALK-1 by immunohistochemistry (IHC). One tumor was negative for ALK-1 by IHC but was positive for ALK fusion by fluorescence in situ hybridization and had TNS1-ALK fusion by next-generation sequencing (NGS). Three other tumors with NGS testing showed one of the following ALK-fusion partners: FN1, DCTN1, and IGFBP5. The EIMS had infiltrative borders, myxoid and hyalinized patterns, epithelioid cells, and no lymphovascular invasion. This tumor was ALK-1 positive by IHC, had ALK rearrangement by fluorescence in situ hybridization and RANBP2-ALK fusion by NGS. Extrauterine disease at time of diagnosis was noted in 2/8 (25%) of IMTs, and in the single case of EIMS. Seven patients had surgery as primary treatment, 1 patient had neoadjuvant chemotherapy and 1 patient declined treatment. Patients with recurrence were treated with a combination of chemotherapy, targeted therapy, radiotherapy or hormonal therapy. Most patients (71.4%) recurred within 24 months (mos). Two thirds of patients were alive with disease at last follow up (mean 43.6 mos). The patient with EIMS was alive with disease at 22 mos. IMT referral cases were initially diagnosed as smooth muscle tumors in 87.5% of cases; while the EIMS was diagnosed as high-grade endometrial stromal sarcoma. Lack of consideration of IMT in the differential diagnosis of smooth muscle tumors with myxoid features can result in misdiagnosis and under-utilization of targeted therapy in these patients.

Malignant Peritoneal Mesothelioma Associated With Endometriosis: A Clinicopathologic Study of 15 Cases.

Only a few cases of malignant peritoneal mesothelioma (MPeM) associated with endometriosis have been published; with chronic inflammation of the peritoneum associated with the latter being postulated as an inducing factor in the pathogenesis of this tumor. We assessed the clinicopathologic characteristics of MPeM associated with endometriosis to determine if there were other factors besides inflammation that may contribute to the pathogenesis in this patient population. Fifteen MPeM associated with endometriosis were retrieved from our files. Most presented with abdominal/pelvic pain, mass or distention; median age was 45 yr. Only 16% of patients had a history of asbestos exposure. In contrast, a third of the patients had a personal history of other neoplasms, and >80% had a family history of malignancies. Although most tumors had gross and microscopic features typical of MPeM, some had confounding features including "adhesion-like" appearance or gelatinous cysts/nodules, and signet ring cells. Tumors were epithelioid (9) and biphasic (6). MPeM was misdiagnosed as Müllerian carcinoma in 40% of cases. All patients (n=15) had cytoreductive surgery in addition to other therapies. Only 2/12 patients died of disease (17%). The 3- and 5-yr overall survival was 90%. MPeM associated with endometriosis tends to occur in patients with personal/familial history of malignancies, which may be a predisposing factor. In light of this finding, the role of endometriosis in the pathogenesis of MPeM is likely less relevant. The favorable outcome seen in these patients may be related to germline mutations or the hormonal milieu and needs further investigation.

Efficacy, Safety, and Biomarker Analysis of Combined PD-L1 (Atezolizumab) and VEGF (Bevacizumab) Blockade in Advanced Malignant Peritoneal Mesothelioma.

Malignant peritoneal mesothelioma (MPeM) is a rare but aggressive malignancy with limited treatment options. VEGF inhibition enhances efficacy of immune-checkpoint inhibitors by reworking the immunosuppressive tumor milieu. Efficacy and safety of combined PD-L1 (atezolizumab) and VEGF (bevacizumab) blockade (AtezoBev) was assessed in 20 patients with advanced and unresectable MPeM with progression or intolerance to prior platinum-pemetrexed chemotherapy. The primary endpoint of confirmed objective response rate per RECISTv1.1 by independent radiology review was 40% [8/20; 95% confidence interval (CI), 19.1-64.0] with median response duration of 12.8 months. Six (75%) responses lasted for >10 months. Progression-free and overall survival at one year were 61% (95% CI, 35-80) and 85% (95% CI, 60-95), respectively. Responses occurred notwithstanding low tumor mutation burden and PD-L1 expression status. Baseline epithelial-mesenchymal transition gene expression correlated with therapeutic resistance/response (r = 0.80; P = 0.0010). AtezoBev showed promising and durable efficacy in patients with advanced MPeM with an acceptable safety profile, and these results address a grave unmet need for this orphan disease. SIGNIFICANCE: Efficacy of atezolizumab and bevacizumab vis-à-vis response rates and survival in advanced peritoneal mesothelioma previously treated with chemotherapy surpassed outcomes expected with conventional therapies. Biomarker analyses uncovered epithelial-mesenchymal transition phenotype as an important resistance mechanism and showcase the value and feasibility of performing translationally driven clinical trials in rare tumors.See related commentary by Aldea et al., p. 2674.This article is highlighted in the In This Issue feature, p. 2659.

TP53 variant allele frequency correlates with the chemotherapy response score in ovarian/fallopian tube/peritoneal high-grade serous carcinoma.

Molecular findings in ovarian, fallopian tube, and peritoneal high-grade serous carcinoma (HGSCa) are emerging as potential prognostic indicators. The chemotherapy response score (CRS) has been proposed as a histologic-based prognostic factor in patients with HGSCa treated with neoadjuvant chemotherapy (NACT). No study details the relationship between the mutational landscape of HGSCa and the CRS. This study addresses this issue using next-generation sequencing (NGS). We retrospectively identified 25 HGSCas treated with NACT and pathology material available to calculate the CRS. All cases had NGS on the primary debulking specimen post-NACT. The three-tier Böhm CRS was applied to the omentum or adnexa and calculated as a combined score. Tumor mutation burden (TMB) and TP53 variant allele frequency (VAF) were calculated and used in correlative analysis. All cases had at least one mutation, most commonly TP53 (25 cases, 100%). Other mutations were BRCA2 (one case, 4%), ARID1A (two cases, 8%), and 1 (4%) of each of the following: ERBB2, NTRK3, STK11, NTRK2, TSC1, PIK3CA, NF1, NOTCH3, CDK2, SMAD4, and PMS2. TMB ranged from 2.58 to 7.75 (median 3.84). There was no statistically significant relationship between the TMB and omental CRS, R-squared = 0.011 (P = 0.62); adnexal CRS, R-squared = 0.005 (P = 0.74); or with the combined CRS, R-squared = 0.009 (P = 0.65). Statistically significant correlation was found between the TP53 VAF and the omental CRS (R-squared = 0.28, P = 0.007), adnexal CRS (R-squared = 0.26, P = 0.01), and the combined CRS (R-squared = 0.33, P = 0.0026). The TP53 VAF was adjusted for percent of tumor present on the slide resulting in an average per cell TP53 mutational load, resulting in similar results with a statistically significant correlation between the average per cell TP53 mutational load and the omental CRS (R-squared = 0.27, P = 0.02), adnexal CRS (R-squared = 0.16, P = 0.05), and the combined CRS (R-squared = 0.23, P = 0.02). In summary, NGS confirmed TP53 mutations in all cases of HGSCa. TMB showed no correlation with the CRS. TP53 VAF and average per cell TP53 mutational load showed significant correlation with the CRS, whether graded on the adnexa or omentum or as a combined score, indicating concordance between molecular and histological findings following NACT.

A Modified 2 Tier Chemotherapy Response Score (CRS) and Other Histopathologic Features for Predicting Outcomes of Patients with Advanced Extrauterine High-Grade Serous Carcinoma after Neoadjuvant Chemotherapy.

Background: The impact of chemotherapy response score (CRS) on prognosis has varied among studies. We addressed the prognostic significance of CRS and the prognostic value of previously undescribed histologic features using a cohort of 245 patients. Methods: Retrospective study in patients with advanced extrauterine high-grade serous carcinomas treated with neoadjuvant chemotherapy followed by interval tumor reductive surgery from 1990 to 2018 in our hospital. Gynecologic pathologists assessed tumor CRS and other histologic features. Clinical information was collected, and multivariate analyses were conducted. Results: A modified 2 tier CRS (CRS 1/2 versus CRS 3) was significantly associated, independent of scoring site (omental versus adnexal), with overall survival (OS) (omentum, p = 0.018; adnexa, p = 0.042; entire cohort, p = 0.002) and progression-free survival (PFS) (p = 0.021, p = 0.035, and p = 0.001, respectively). On multivariate survival analysis, 2 tier CRS, oncocytic change, inflammation, and desmoplasia were significant for OS (p = 0.034, p = 0.020, p = 0.007, and p = 0.010, respectively). Likewise, 2 tier CRS, inflammation, and desmoplasia were significant for PFS (p = 0.012, p = 0.003, p = 0.011, respectively). Conclusions: The modified 2 tier CRS was significantly associated with survival, independent of scoring site. Additional histologic features including oncocytic change, inflammation, and desmoplasia can also predict patient outcomes.

Endocervical Adenocarcinoma, Gross Examination, and Processing, Including Intraoperative Evaluation: Recommendations From the International Society of Gynecological Pathologists.

The International Society of Gynecological Pathologists (ISGyP) Endocervical Adenocarcinoma Project aims to provide evidence-based guidance for the pathologic evaluation, classification, and reporting of endocervical adenocarcinoma. This review presents the recommendations pertaining to gross evaluation and intraoperative consultation of specimens obtained from patients in the setting of cervical cancer. The recommendations are the product of review of published peer-reviewed evidence, international guidelines and institutional grossing manuals, as well as deliberation within this working group. The discussion presented herein details the approach to the different specimen types encountered in practice: loop electrosurgical excision procedure, cone, trachelectomy, radical hysterectomy, pelvic exenteration, and lymphadenectomy specimens. Guidelines for intraoperative evaluation of trachelectomy and sentinel lymph node specimens are also addressed. Correlation with ISGyP recommendations on cancer staging, which appear as a separate review in this issue, is also included when appropriate. While conceived in the framework of endocervical adenocarcinoma, most of the discussion and recommendations can also be applied to other cervical malignancies.

The Silva Pattern-based Classification for HPV-associated Invasive Endocervical Adenocarcinoma and the Distinction Between In Situ and Invasive Adenocarcinoma: Relevant Issues and Recommendations From the International Society of Gynecological Pathologists.

The Silva pattern-based classification for human papilloma virus-associated invasive adenocarcinoma has emerged as a reliable system to predict risk of lymph node metastasis and recurrences. Although not a part of any staging system yet, it has been incorporated in synoptic reports as established by the College of American Pathologists (CAP) and the International Collaboration on Cancer Reporting (ICCR). Moreover, the current National Comprehensive Cancer Network (NCCN) guidelines include this classification as an "emergent concept." In order to facilitate the understating and application of this new classification by all pathologists, the ISGyP Endocervical Adenocarcinoma Project Working Group presents herein all the current evidence on the Silva classification and aims to provide recommendations for its implementation in practice, including interpretation, reporting, and application to biopsy and resection specimens. In addition, this article addresses the distinction of human papilloma virus-associated adenocarcinoma in situ and gastric type adenocarcinoma in situ from their invasive counterparts.

Immunohistochemical Loss of DPC4 in Tumors With Mucinous Differentiation Arising in or Involving the Gynecologic Tract.

DPC4 immunohistochemistry (IHC) is usually part of the work-up of mucinous neoplasms in the ovary where the distinction between an ovarian primary and metastatic pancreaticobiliary adenocarcinoma (PanACa) must be made. Although DPC4 IHC is lost in about 55% (46%-61%) of PanACas and typically retained in most primary ovarian mucinous neoplasms, no study has evaluated the expression of this marker in a large cohort of neoplasms arising in or involving gynecologic (GYN) organs. In this study, we retrospectively analyzed the expression of DPC4 IHC in a total of 251 tumors and lesions related to the GYN tract in which DPC4 IHC stain was performed during the initial pathology evaluation. Of these, 138 were primary GYN tumors and lesions, 31 were metastatic GYN tumors involving non-GYN sites, and 83 were metastatic non-GYN tumors involving the GYN tract. We identified 27 cases with loss of DPC4 IHC expression of which 20 cases met the inclusion criteria (i.e. clinical information was available to determine the site of tumor origin). We observed that loss of DPC4 nuclear expression was most commonly seen in tumors of endocervical origin (n=7), of which 5 were gastric-type cervical adenocarcinomas (GCxACa) and 2 were usual-type cervical adenocarcinomas, either primary or metastatic. This was followed by tumors of the pancreaticobiliary tract (n=5), ovary (n=2), and appendix (n=1). In addition, 1 gastric-type vaginal adenocarcinoma (GVaACa) also showed loss of DPC4. Our findings indicate that in female patients with mucinous neoplasms involving the ovary or other sites, with loss of DPC4 by IHC, and negative pancreaticobiliary imaging, the possibility of an occult GCx/GVaACa, and rarely an ovarian primary must be considered.

High-grade Neuroendocrine Carcinomas of the Vulva: A Clinicopathologic Study of 16 Cases.

Vulvar high-grade neuroendocrine carcinomas (HGNECs) are rare and primarily thought to represent Merkel cell carcinoma (MCC). We present the clinicopathologic features of 16 such cases, the largest series to date. Patients were most often White, postmenopausal, and symptomatic from a palpable vulvar mass/nodule. Tumors ranged from 0.7 to 6 cm and most commonly involved the labium majus. Majority of the cases were pure HGNECs (15/16) with small cell (SC) morphology (14/16); 2 were large cell neuroendocrine carcinomas, of which 1 was combined with moderately differentiated adenocarcinoma. All tumors expressed synaptophysin. Of the 14 HGNECs with SC morphology, 6 were CK20-positive MCCs with characteristic CAM5.2 and neurofilament (NF) expression. Five of these MCCs were positive for Merkel cell polyoma virus large T-antigen (MCPyVLTAg). In contrast, 6 HGNECs with SC morphology were negative for CK20, NF, and MCPyVLTAg and classified as SCNECs. High-risk human papilloma virus was positive in all SCNECs and negative in all MCCs. One case of HGNEC with SC morphology could not be entirely characterized due to lack of tissue for ancillary testing. Five of 12 (42%) cases had a discrepant diagnosis initially rendered. Most patients (10/15) presented with International Federation of Gynecology and Obstetrics stage III or IV disease. Usual sites of metastasis included inguinal lymph node, liver, bone, and lung. Twelve patients underwent surgery with adjuvant chemotherapy and/or radiation therapy, 1 received adjuvant immunotherapy, and 1 patient received neoadjuvant chemotherapy followed by surgery and adjuvant radiation therapy. Median overall survival was 24 months (range: 7 to 103 mo), and overall 5-year survival was 12% (95% confidence interval: 1% to 39%). In summary, vulvar HGNECs are rare, aggressive neoplasms that can be further subclassified into MCC, SCNEC, and large cell neuroendocrine carcinoma. CK20, CAM5.2, NF, TTF-1, MCPyVLTAg, and high-risk human papilloma virus facilitate the distinction of MCC from SCNEC. Proper identification of vulvar HGNECs is critical for patient management.