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Objective Broad adoption of digital pathology (DP) is still lacking, and examples for DP connecting diagnostic, research, and educational use cases are missing. We blueprint a holistic DP solution at a large academic medical center ubiquitously integrated into clinical workflows; researchapplications including molecular, genetic, and tissue databases; and educational processes. Materials and Methods We built a vendor-agnostic, integrated viewer for reviewing, annotating, sharing, and quality assurance of digital slides in a clinical or research context. It is the first homegrown viewer cleared by New York State provisional approval in 2020 for primary diagnosis and remote sign-out during the COVID-19 (coronavirus disease 2019) pandemic. We further introduce an interconnected Honest Broker for BioInformatics Technology (HoBBIT) to systematically compile and share large-scale DP research datasets including anonymized images, redacted pathology reports, and clinical data of patients with consent. Results The solution has been operationally used over 3 years by 926 pathologists and researchers evaluating 288 903 digital slides. A total of 51% of these were reviewed within 1 month after scanning. Seamless integration of the viewer into 4 hospital systems clearly increases the adoption of DP. HoBBIT directly impacts the translation of knowledge in pathology into effective new health measures, including artificial intelligence–driven detection models for prostate cancer, basal cell carcinoma, and breast cancer metastases, developed and validated on thousands of cases. Conclusions We highlight major challenges and lessons learned when going digital to provide orientation for other pathologists. Building interconnected solutions will not only increase adoption of DP, but also facilitate next-generation computational pathology at scale for enhanced cancer research.

Objective Uterine carcinosarcoma (UCS) is a rare but aggressive cancer. In early-stage disease data guiding treatment is sparse. The purpose of this review is to summarize the findings from the 2019 NRG oncology group summer symposium meeting as well as a review of the current literature, with a particular focus on molecular targets, ongoing clinical trials, and treatment of early and advanced/recurrent disease. Methods A combination of expert presentations and an extensive literature search was undertaken to summarize the literature in this review. MEDLINE was queried for peer-reviewed publications on UCS. This search was not limited by year or study design, but was limited to English language publications. ClinicalTrials.gov was queried for ongoing trials in UCS. Results UCS is a rare cancer that is biphasic, with the carcinomatous component driving its aggressive nature. Level 3 evidence regarding early stage disease is lacking, but retrospective data suggests adjuvant therapy is warranted. The recent results of GOG 261 have contributed valuable information towards treatment strategy, including use of paclitaxel and carboplatin for UCS. Clinical trials are ongoing to investigate new targeted agents in UCS. Conclusion Ongoing endometrial cancer clinical trials now include UCS patients. In combination with advances in molecular profiling, this will provide patients with UCS improved therapeutic options. Until that time, surgical resection and traditional cytotoxic chemotherapy remains standard of care.

High-grade endometrial stromal sarcoma (HGESS) may harbor YWHAE-NUTM2A/B fusion, ZC3H7B-BCOR fusion, and BCOR internal tandem duplication (ITD). NTRK3 upregulation and pan-Trk expression were reported in soft tissue lesions that share similar morphology and genetic abnormalities. To confirm these findings in HGESS, differential expression analysis was performed at gene level comparing 11 HGESS with 48 other uterine sarcomas, including 9 low-grade endometrial stromal sarcomas, 23 undifferentiated uterine sarcomas, and 16 leiomyosarcomas, using targeted RNA sequencing data. Pan-Trk immunohistochemistry was performed on 35 HGESS, including 10 tumors with RNA expression data, with genotypes previously confirmed by targeted RNA sequencing, fluorescence in situ hybridization, and/or genomic PCR. Unsupervised hierarchical clustering of the top 25% of differentially expressed probes identified three molecular groups: (1) high NTRK3, FGFR3, RET, BCOR, GLI1, and PTCH1 and low ESR1 expression; (2) low NTRK3, FGFR3, RET, BCOR, GLI1, and PTCH1 and high ESR1 expression; and (3) low NTRK3, FGFR3, RET, BCOR, GLI1, PTCH1, and ESR1 expression. Among HGESS, 64% of tumors clustered in group 1, while 27% clustered in group 2. Cytoplasmic and/or nuclear pan-Trk staining of variable extent and intensity was seen in 91% of HGESS regardless of cyclin D1 and/or BCOR positivity. ER and PR expression was seen in 44% of HGESS despite ESR1 downregulation. Two patients with ER and PR positive but ESR1 downregulated stage I HGESS were treated with endocrine therapy, and both recurred at 12 and 36 months after primary resection. By RNA expression, HGESS appear homogenous and distinct from other uterine sarcomas by activation of kinases, including NTRK3, and sonic hedgehog pathway genes along with downregulation of ESR1. Most HGESS demonstrate pan-Trk staining which may serve as a diagnostic biomarker. ESR1 downregulation is seen in some HGESS that express ER and PR which raises implications in the utility of endocrine therapy in these patients.

Purpose: Copy number–high endometrial carcinomas were described by The Cancer Genome Atlas as high-grade endometrioid and serous cancers showing frequent copy-number alterations (CNA), low mutational burden (i.e., non-hypermutant), near-universal TP53 mutation, and unfavorable clinical outcomes. We sought to investigate and compare the clinicopathologic and molecular characteristics of non-hypermutant TP53-altered endometrial carcinomas of four histologic types. Experimental Design: TP53-mutated endometrial carcinomas, defined as TP53-mutant tumors lacking microsatellite instability or pathogenic POLE mutations, were identified (n = 238) in a cohort of 1,239 endometrial carcinomas subjected to clinical massively parallel sequencing of 410–468 cancer-related genes. Somatic mutations and CNAs (n = 238), and clinicopathologic features were determined (n = 185, initial treatment planning at our institution). Results: TP53-mutated endometrial carcinomas encompassed uterine serous (n = 102, 55.1%), high-grade endometrial carcinoma with ambiguous features/not otherwise specified (EC-NOS; n = 44, 23.8%), endometrioid carcinomas of all tumor grades (n = 28, 15.1%), and clear cell carcinomas (n = 11, 5.9%). PTEN mutations were significantly more frequent in endometrioid carcinomas, SPOP mutations in clear cell carcinomas, and CCNE1 amplification in serous carcinomas/EC-NOS; however, none of these genomic alterations were exclusive to any given histologic type. ERBB2 amplification was present at similar frequencies across TP53-mutated histologic types (7.7%–18.6%). Although overall survival was similar across histologic types, serous carcinomas presented more frequently at stage IV, had more persistent and/or recurrent disease, and reduced disease-free survival. Conclusions: TP53-mutated endometrial carcinomas display clinical and molecular similarities across histologic subtypes. Our data provide evidence to suggest performance of ERBB2 assessment in all TP53-mutated endometrial carcinomas. Given the distinct clinical features of serous carcinomas, histologic classification continues to be relevant.

Although diagnosis of high-grade uterine mesenchymal tumors (high-grade UMTs) exhibiting classic morphologic features is straightforward, diagnosis is more challenging in tumors in which prototypical features are poorly developed, focal and/or co-exist with features seen in other neoplasms. Here, we sought to define the repertoire of somatic genetic alterations in diagnostically challenging UMTs with myomelanocytic differentiation, including some reported as perivascular epithelioid cell tumors (PEComas). In 17 samples from 15 women, the tumors were histologically heterogeneous. Immunohistochemical expression of at least one melanocytic marker (HMB45, Melan-A or MiTF) was identified in all tumors, and of myogenic markers (desmin or SMA) in most tumors. Targeted massively parallel sequencing revealed several genetic alterations, most commonly in TP53 (41% mutation, 12% deletion), TSC2 (29% mutation, 6% deletion), RB1 (18% deletion), ATRX (24% mutation), MED12 (12% mutation), BRCA2 (12% deletion), CDKN2A (6% deletion) as well as FGFR3, NTRK1 and ERBB3 amplification (each 6%). Gene rearrangements (JAZF1-SUZ12; DNAJB6-PLAG1 and SFPQ-TFE3) were identified in three tumors. Integrating histopathologic, immunohistochemical and genetic findings, tumors from 4 patients were consistent with malignant PEComa (one TFE3-rearranged); 6 were classified as leiomyosarcomas; 3 showed overlapping features of PEComa and other sarcoma types (leiomyosarcoma or low-grade endometrial stromal sarcoma); and 2 were classified as sarcoma, not otherwise specified. Our findings suggest that diagnostically challenging UMTs with myomelanocytic differentiation represent a heterogeneous group of neoplasms which harbor a diverse repertoire of somatic genetic alterations; these genetic alterations can aid classification.

Objective To evaluate the impact of tumor fragmentation on oncologic outcomes in patients with stage I uterine leiomyosarcoma (uLMS). Methods We identified all patients diagnosed with stage I uLMS presenting to our institution within three months of primary surgery, 1/2000–1/2019. Patients with recurrent disease were excluded. The non-morcellated group had total hysterectomy without documented specimen fragmentation; the morcellated group, total hysterectomy with documented specimen fragmentation. We defined fragmentation as manual fragmentation or morcellation (via power morcellator or otherwise) of the specimen in peritoneal cavity or vagina. Appropriate statistical analyses were performed. Results 152 patients met inclusion criteria. 107 (70%) underwent total hysterectomy (non-morcellated); 45 (30%) underwent morcellation. Median age at diagnosis for the entire cohort was 55 years (range 30–91). Median follow-up was 42.1 months (range 1.1–197.8). 40 (26.3%) patients had primary surgery at our institution, 112 (73.7%) at an outside hospital. In total 110 (72.3%) recurred: 72/107 (67.2%) non-morcellated; 38/44 (86.3%) morcellated. Median progression-free survival (PFS) for non-morcellated versus morcellated was 13.8 (95%CI 9.2–20.2) versus 7.3 months (95%CI 3–13.1), HR 1.5 (95%CI 1.02–2.24); P = 0.04. Median overall survival (OS) for non-morcellated versus morcellated was 82.1 (95%CI 52.4–122) versus 47.8 months (95%CI 28.5–129.6), HR 1.1 (95%CI 0.67–1.82); P = 0.7. Among patients with recurrence, 69.4% of non-morcellated recurred at hematogenous sites only, 18.1% recurred in peritoneum only; 28.9% of morcellated recurred at hematogenous sites, 63.2% in peritoneum. Race, lymphovascular invasion, postoperative chemotherapy, were independently associated with PFS. Mitotic index was independently associated with OS. Conclusions Tumor fragmentation/morcellation was associated with significantly higher risk of recurrence and a nearly 4-fold increase in peritoneal recurrence. Prognostic biomarkers remain important in predicting oncologic outcomes, independent of fragmentation or treatment.

Uterine epithelioid and myxoid leiomyosarcomas and inflammatory myofibroblastic tumors are rare mesenchymal neoplasms. Next-generation sequencing recently detected novel PGR fusions in uterine epithelioid leiomyosarcomas that demonstrate characteristic rhabdoid and spindled morphology. PLAG1 gene fusions have also been identified in a subset of myxoid leiomyosarcomas and are associated with PLAG1 overexpression. ALK rearrangements underpin the vast majority of uterine inflammatory myofibroblastic tumors, which demonstrate morphologic, and immunohistochemical features similar to those of inflammatory myofibroblastic tumors elsewhere. This review summarizes the morphologic, immunophenotypic, and molecular genetic features of PGR fusion-positive epithelioid leiomyosarcoma, PLAG1 fusion-positive myxoid leiomyosarcoma, and inflammatory myofibroblastic tumors of the uterus.

Objective Uterine carcinosarcoma (UCS) is a rare but aggressive cancer. In early-stage disease data guiding treatment is sparse. The purpose of this review is to summarize the findings from the 2019 NRG oncology group summer symposium meeting as well as a review of the current literature, with a particular focus on molecular targets, ongoing clinical trials, and treatment of early and advanced/recurrent disease. Methods A combination of expert presentations and an extensive literature search was undertaken to summarize the literature in this review. MEDLINE was queried for peer-reviewed publications on UCS. This search was not limited by year or study design, but was limited to English language publications. ClinicalTrials.gov was queried for ongoing trials in UCS. Results UCS is a rare cancer that is biphasic, with the carcinomatous component driving its aggressive nature. Level 3 evidence regarding early stage disease is lacking, but retrospective data suggests adjuvant therapy is warranted. The recent results of GOG 261 have contributed valuable information towards treatment strategy, including use of paclitaxel and carboplatin for UCS. Clinical trials are ongoing to investigate new targeted agents in UCS. Conclusion Ongoing endometrial cancer clinical trials now include UCS patients. In combination with advances in molecular profiling, this will provide patients with UCS improved therapeutic options. Until that time, surgical resection and traditional cytotoxic chemotherapy remains standard of care.

Extramammary Paget disease (EMPD) is a rare cutaneous adenocarcinoma of the anogenital region most commonly treated with surgical excision. Surgical margin clearance is often problematic and recurrence rates remain high indicating the need for additional therapeutic options. Topical immunomodulators have been used with reported success suggesting EMPD may respond to other immunotherapies. This study investigates EMPD protein expression of targetable B7 family members and cancer/testis antigens (CTAs) B7-H3, B7-H4, PD-L1, PD-L2, MAGE-A, and NY-ESO-1 and components of antigen presenting machinery B2M and MHC-I. Fifty-seven specimens from 48 patients (31 female and 17 male), representing in situ, invasive, and metastatic disease of primary and secondary origin were stained and scored (627 total slides). The percentage of cases expressing each immune regulatory molecule in the in situ followed by invasive tumor components was: B7-H3 (94, 90), B7-H4 (82, 78), PD-L1 (6, 10), MAGE-A (39, 50), NY-ESO-1 (16, 20), B2M (100, 89), and MHC-I (78, 79). PD-L2 was negative in all cases. There was high correlation between marker expression within the in situ and invasive tumor components of the same case. B7-H4 was preferentially expressed in primary cutaneous EMPD. Co-expression of B7 family members B7-H3 and B7-H4 was found within the in situ and invasive tumor components of 74% and 48% of cases, respectively. These findings provide an initial characterization of EMPD tumor cell expression of B7-H3, B7-H4, PD-L1, PD-L2, MAGE-A, and NY-ESO-1 and indicate the potential for new immunotherapeutic options for patients with EMPD.

Sinonasal undifferentiated carcinoma (SNUC) is an aggressive malignancy harboring IDH2 R172 mutations in >80% cases. We explored the potential of genome-wide DNA methylation profiling to elucidate tumor biology and improve the diagnosis of sinonasal undifferentiated carcinoma and its histologic mimics. Forty-two cases, including sinonasal undifferentiated, large cell neuroendocrine, small cell neuroendocrine, and SMARCB1-deficient carcinomas and olfactory neuroblastoma, were profiled by Illumina Infinium Methylation EPIC array interrogating >850,000 CpG sites. The data were analyzed using a custom bioinformatics pipeline. IDH2 mutation status was determined by the targeted exome sequencing (MSK- IMPACTTM) in most cases. H3K27 methylation level was assessed by the immunohistochemistry-based H-score. DNA methylation-based semi-supervised hierarchical clustering analysis segregated IDH2 mutants, mostly sinonasal undifferentiated (n = 10) and large cell neuroendocrine carcinomas (n = 4), from other sinonasal tumors, and formed a single cluster irrespective of the histologic type. t-distributed stochastic neighbor embedding dimensionality reduction analysis showed no overlap between IDH2 mutants, SMARCB1-deficient carcinoma and olfactory neuroblastoma. IDH2 mutants demonstrated a global methylation phenotype and an increase in repressive trimethylation of H3K27 in comparison to IDH2 wild-type tumors (p < 0.001). Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed no difference in pathway activation between IDH2-mutated sinonasal undifferentiated and large cell neuroendocrine carcinomas. In comparison to SMARCB1-deficient, IDH2-mutated carcinomas were associated with better disease-free survival (p = 0.034) and lower propensity for lung metastasis (p = 0.002). ARID1A mutations were common in small cell neuroendocrine carcinoma but not among IDH2 mutants (3/3 versus 0/18 and p < 0.001). IDH2 mutations in sinonasal carcinomas induce a hypermethylator phenotype and define a molecular subgroup of tumors arising in this location. IDH2- mutated sinonasal undifferentiated carcinoma and large cell neuroendocrine carcinoma likely represent a phenotypic spectrum of the same entity, which is distinct from small cell neuroendocrine and SMARCB1-deficient sinonasal carcinomas. DNA methylation-based analysis of the sinonasal tumors has potential to improve the diagnostic accuracy and classification of tumors arising in this location.

Genetic alterations in uterine myxoid leiomyosarcoma are unknown. We investigate the clinicopathologic features of 19 uterine tumors previously diagnosed as myxoid leiomyosarcomas in which tumoral RNA was subjected to targeted RNA sequencing. PLAG1, BCOR, BCORL1, HMGA2, and ALK break-apart fluorescence in situ hybridization (FISH) and BCOR, PLAG1, and ALK immunohistochemistry were performed in cases which failed or lacked fusions by sequencing. The diagnosis of myxoid leiomyosarcoma was confirmed in 15 cases after exclusion of 4 tumors with BCOR and ALK rearrangements. These 15 patients presented at a median age of 50 years with stage I (3), II (2), III (2), and IV (1), respectively; stage was unknown in 7 cases. Tumor size ranged from 10 to 24 cm. Matrix was myxoid in all tumors and also eosinophilic in 2. Cells were spindled, epithelioid, and both in 10, 2 and 3 tumors and showed mild, moderate, and severe nuclear atypia in 3, 8, and 4 tumors, respectively. Mitotic index ranged from

AIMS To characterise the genetic alterations in adult primary uterine rhabdomyosarcomas (uRMSs) and to investigate whether these tumours are genetically distinct from uterine carcinosarcomas (UCSs). METHODS AND RESULTS Three tumours originally diagnosed as primary adult pleomorphic uRMS were subjected to massively parallel sequencing targeting 468 cancer-related genes and RNA-sequencing. Mutational profiles were compared with those of UCSs (n = 57) obtained from The Cancer Genome Atlas. Sequencing data analyses were performed using validated bioinformatic approaches. Pathogenic TP53 mutations and high levels of genomic instability were detected in the three cases. uRMS1 harboured a likely pathogenic YTHDF2-FOXR1 fusion. uRMS2 harboured a PPP2R1A hotspot mutation and amplification of multiple genes, including WHSC1L1, FGFR1, MDM2, and CCNE1, whereas uRMS3 harboured an FBXW7 hotspot mutation and an ANKRD11 homozygous deletion. Hierarchical clustering of somatic mutations and copy number alterations revealed that these tumours initially diagnosed as pleomorphic uRMSs and UCSs were similar. Subsequent comprehensive pathological re-review of the three uRMSs revealed previously unidentified minute pan-cytokeratin-positive atypical glands in one case (uRMS3), favouring its reclassification as UCS with extensive rhabdomyosarcomatous overgrowth. CONCLUSIONS Adult pleomorphic uRMSs harbour TP53 mutations and high levels of copy number alterations. Our findings underscore the challenge in discriminating between uRMS and UCS with rhabdomyosarcomatous differentiation.

Highlights • In a bleeding postmenopausal woman with didelphys uterus, endometrial biopsy should be taken from both uterine cavities. • Sentinel lymph node mapping has not been previously described in the setting of endometrial cancer and uterine didelphys. • Routine sentinel lymph node mapping was successfully performed in a patient with endometrial cancer and uterine didelphys.

OBJECTIVE: To characterize and compare the molecular subtypes and profiles of prospectively-accrued newly-diagnosed early- and advanced-stage endometrial cancers (ECs). METHODS: EC patients consented to an IRB-approved protocol of massively parallel sequencing of 410–468 cancer-related genes; 175 ECs of 7 histologic types (n=135 FIGO stages I/II, n=40 FIGO stages III/IV) were included. Previously reported sequencing data from 99 additional advanced-stage ECs were retrieved for comparisons. RESULTS: Irrespective of histologic type, all 175 ECs could be stratified into the molecular subtypes, with 75 (43%) being of p53 wild-type, 49 (28%) MMR-deficient, 39 (22%) p53 abnormal and 12 (7%) of POLE molecular subtypes. Subtype distribution, mutational and copy number profiles varied according to histologic type. In endometrioid ECs, genetic alterations varied according to histologic grade. Potential therapeutic targets, including high tumor mutational burden, ERBB2 amplification and PIK3CA hotspot mutations, were found across histologic types in 63% (n=110) of all ECs. Compared to their early-stage counterparts, advanced-stage endometrioid ECs had a significantly higher fraction of genome altered (median 0.1% vs 12%, p0.05) and PIK3CA mutations (46% vs 27%, p>0.05). Whole-genome doubling was found in advanced- but not early-stage carcinosarcomas and clear cell carcinomas. CONCLUSIONS: Our findings demonstrate the molecular heterogeneity within and across histologic types of EC and the increased genomic complexity of advanced-stage ECs. Molecular subtypes are present across EC histologic types and may help stratify EC patients for prognostic and therapeutic purposes.

NTRK fusion-positive uterine sarcoma is a recently recognized mesenchymal tumor that is defined by its morphologic resemblance to soft tissue fibrosarcoma, NTRK gene rearrangements, and potential response to Trk inhibition. Reported lesions affect premenopausal women with a median age of 32 yr, and most arise in the uterine cervix. Haphazard, storiform, or herringbone patterns of spindle cells with mild to moderate nuclear atypia are characteristic. SMA, CD34, and S100 are variably positive, but tumors are negative for desmin, ER, PR, and SOX10 and retain H3K27me3 expression. While pan-Trk immunohistochemistry is positive in these tumors, it has decreased sensitivity and specificity in the evaluation of sarcomas in general and the detection of NTRK3 rearrangements. A variety of molecular methods such as fluorescence in situ hybridization and next-generation sequencing may be useful in confirming NTRK fusion in fibrosarcoma-like uterine sarcomas.

Aims Uterine sarcomas can be grouped into tumours with pathognomonic genetic fusions such as low-grade endometrial stromal sarcoma (LGESS), high-grade endometrial stromal sarcoma (HGESS) and inflammatory myofibroblastic tumour (IMT), and tumours lacking genetic fusions such as leiomyosarcoma (LMS) and undifferentiated uterine sarcoma (UUS). The latter group frequently harbours TP53 mutations. This study aims to evaluate TP53 mutation by immunohistochemistry in fusion-positive uterine sarcomas. Methods and results We performed p53 immunohistochemical staining on 124 uterine sarcomas harboring genetic fusions and 38 fusion-negative LMS and UUS. These included 41 HGESS with YWHAE, BCOR or BCORL1 genetic fusion/ rearrangement, 13 IMT with ALK fusion, 12 sarcomas with NTRK1/3 fusion, 3 sarcomas with PDGFB fusion and 55 LGESS with JAZF1, SUZ12 PHF1 genetic fusion/rearrangement). All HGESS, LGESS, IMT and sarcomas with PDGFB fusion showed wild-type p53 expression pattern. Among NTRK1/3 sarcomas, a TPR-NTRK1 sarcoma with nuclear pleomorphism showed mutation-type p53 expression patterns. The remaining 11 NTRK1/3 sarcomas showed wild-type p53 expression pattern, except for the subclonal p53 mutation-type staining in a minor pleomorphic focus of a NTRK3 sarcoma. 21 of 27 (78%) LMS and 6 of 9 (67%) UUS showed mutation-type p53 expression pattern. Conclusion P53 immunohistochemistry may be considered in the initial work-up of a uterine sarcoma as mutation-type staining would render the possibility of a fusion positive sarcoma very unlikely. Mutation-type p53 expression pattern however can be seen in a small subset of NTRK1/3 sarcoma exhibiting pleomorphic round/ovoid cell histology, which may represent a mechanism of progression in these tumors.

PURPOSE To detect alterations in DNA damage repair (DDR) genes, measure homologous recombination deficiency (HRD), and correlate these findings with clinical outcome in patients with leiomyosarcoma (LMS). PATIENTS AND METHODS Patients with LMS treated at Memorial Sloan Kettering (MSK) Cancer Center who consented to prospective targeted next-generation sequencing with MSK-IMPACT were screened for oncogenic somatic variants in one of 33 DDR genes; where feasible, an experimental HRD score was calculated from IMPACT data. Progression-free survival (PFS) and overall survival (OS) were estimated after stratifying patients by DDR gene alteration status and HRD score. RESULTS Of 211 patients with LMS, 20% had an oncogenic DDR gene alteration. Univariable analysis of PFS in 117 patients who received standard frontline chemotherapy in the metastatic setting found that an altered homologous recombination pathway gene was significantly associated with shorter PFS (hazard ratio [HR], 1.79; 95% CI, 1.04 to 3.07; P = .035). Non- BRCA homologous recombination gene alteration was associated with shorter PFS (HR, 2.61; 95% CI, 1.35 to 5.04; P = .004) compared with BRCA-altered and wild-type homologous recombination genes. Univariable analysis of OS from diagnosis in the entire cohort of 211 patients found that age, tumor size, number of metastatic sites, localized disease, and non- BRCA homologous recombination gene alteration were significantly associated with OS. On multivariable analysis, non- BRCA homologous recombination pathway gene alteration remained significant (HR, 4.91; 95% CI, 2.47 to 9.76; P < .001). High HRD score was not associated with a different PFS or OS. CONCLUSION Patients with LMS with homologous recombination pathway gene alterations have poor clinical outcomes, particularly those with non- BRCA gene alterations. HRD score calculated from a targeted exome panel did not discern disparate clinical outcomes.

Adenosarcoma can mimic high-grade endometrial stromal sarcoma with ZC3H7B-BCOR fusion that may show entrapped glands and often exhibits diffuse BCOR expression. We encountered diffuse BCOR expression in rare adenosarcomas and sought to define its frequency among a larger cohort of these tumors. BCOR immunohistochemistry was performed on archival formalin-fixed paraffin-embedded tumor tissue in 13 of 14 adenosarcomas with and without stromal overgrowth arising in the uterus or ovary. The staining intensity and percentage of positive tumor nuclei in the mesenchymal component were evaluated. Eleven cases with sufficient tumoral tissue were subjected to fluorescence in situ hybridization for the detection of BCOR, BCORL1, NUTM1, ZC3H7B, and JAZF1 rearrangement. Three cases were subjected to targeted RNA sequencing. BCOR was expressed in 9 of 13 (70%) tumors, including 6 with and 3 without stromal overgrowth. Moderate to strong staining in >70% of cells was seen throughout in 1 low-grade and 6 high-grade tumors, 5 of which had stromal overgrowth. No staining was seen in 3 low-grade and 1 high-grade tumors with stromal overgrowth. One tumor demonstrating extensive sex cord-like differentiation and diffuse BCOR expression harbored JAZF1 and BCORL1 rearrangements. No BCOR or BCORL1 rearrangement was identified in the remaining tumors. BCOR expression is seen in most adenosarcomas with and without stromal overgrowth. BCORL1 rearrangement is seen in rare tumors with diffuse BCOR expression. Assessment of BCOR or BCORL1 rearrangement status is required in adenosarcomas demonstrating BCOR expression.

High-grade histologic transformation of low-grade endometrial stromal sarcoma (LGESS) is rare. Here, we describe the clinicopathologic features and gene fusion status of 12 cases (11 primary uterine corpus and 1 primary vaginal), 11 diagnosed prospectively from 2016, and 1 retrospectively collected. Targeted RNA sequencing and/or fluorescence in situ hybridization was employed in all cases. High-grade transformation was seen at the time of initial diagnosis in eight patients and at the time of recurrence in four patients, 4–11 years after initial diagnosis of LGESS. High-grade morphology consisted of generally uniform population of round to epithelioid cells with enlarged nuclei one to two times larger than a lymphocyte, visible nucleoli, and increased mitotic index (range, 6–30; median, 16 per 10 high-power fields); there was often an associated sclerotic and/or myxoid stroma. Estrogen receptor, progesterone receptor, and CD10 expression was absent or significantly decreased (compared with the low-grade component) in the high-grade foci of five tumors. One tumor demonstrated positive (diffuse and strong) cyclin D1 and BCOR staining. p53 staining was wild type in both components of all eight tumors tested. JAZF1-SUZ12 (n = 6), JAZF1-PHF1 (n = 3), EPC1-PHF1, (n = 1), or BRD8-PHF1 (n = 1) fusions were detected in 11 tumors; no fusions were found in one by targeted RNA sequencing. Patients presented with FIGO stages I (n = 4), II (n = 4), III (n = 1), and IV disease (n = 2). Median overall survival calculated from the time of histologic transformation was 22 months (range, 8 months to 8 years) with five patients who died of disease 8–18 months after transformation. High-grade transformation may occur in LGESS with JAZF1 and PHF1 rearrangements at the time of or years after initial diagnosis. Such high-grade transformation is characterized by nuclear enlargement, prominent nucleoli, and increased mitotic index compared with typical LGESS. Histologic high-grade transformation may herald aggressive behavior.

High-grade endometrial stromal sarcoma likely encompasses underrecognized tumors harboring genetic abnormalities besides YWHAE-NUTM2 fusion. Triggered by three initial endometrial stromal sarcomas with ZC3H7B-BCOR fusion characterized by high-grade morphology and aggressive clinical behavior, we herein investigate the clinicopathologic features of this genetic subset by expanding the analysis to 17 such tumors. All of them occurred in adult women with a median age of 54 (range, 28-71) years. They were predominantly based in the endomyometrium and demonstrated tongue-like and/or pushing myometrial invasion. Most were uniformly cellular and displayed haphazard fascicles of spindle cells with mild to moderate nuclear atypia. Myxoid matrix was seen in 14 of 17 (82%) tumors, and collagen plaques were seen in 8 (47%). The mitotic index was ≥10 mitotic figures/10 high-power fields (HPFs) in 14 of 17 (82%) tumors with a median of 14.5 mitotic figures/10 HPFs. No foci of conventional or variant low-grade endometrial stromal sarcoma were seen. All tumors expressed CD10 with only limited or absent desmin, SMA and/or h-caldesmon staining. ER and PR expression in >5% of cells was seen in 4 of 12 (33%) tumors. Diffuse cyclin D1 and BCOR immunoreactivity was present in 7 of 8 (88%) and 7 of 14 (50%) tumors, respectively. Fluorescence in situ hybridization or targeted RNA sequencing confirmed ZC3H7B-BCOR fusion in all tumors, including four and two previously diagnosed as myxoid leiomyosarcoma and undifferentiated uterine sarcoma, respectively. Limited clinical data suggest that patients present at higher stage and have worse prognosis compared with published outcomes in low-grade endometrial stromal sarcoma. Tumors with ZC3H7B-BCOR fusion constitute a distinct group of endometrial stromal sarcomas with high-grade morphology that should be distinguished from other uterine mesenchymal neoplasms that may demonstrate myxoid morphology.

Recognition of high-grade endometrial stromal sarcoma is important because of its aggressive clinical behavior. Morphologic features of YWHAE-NUTM2 high-grade endometrial stromal sarcoma may overlap with other uterine sarcoma types. BCOR immunoexpression was studied in these tumors and their morphologic mimics to assess its diagnostic utility. BCOR immunohistochemical staining was performed on archival tissue from 28 high-grade endometrial stromal sarcomas with classic morphology (20 YWHAE-NUTM2, 5 ZC3H7B-BCOR, 3 BCOR-ZC3H7B), 3 high-grade endometrial stromal sarcomas with unusual morphology and unknown gene rearrangement status, 66 low-grade endometrial stromal sarcomas, 21 endometrial stromal nodules, 38 uterine leiomyosarcomas, and 19 uterine leiomyomas. Intensity of nuclear staining and percentage of positive tumor cells were recorded. Strong diffuse nuclear BCOR staining (defined as >95% of tumor cells) was seen in the round cell component of all 20 (100%) classic YWHAE-NUTM2 high-grade endometrial stromal sarcomas and the 3 unusual high-grade endometrial stromal sarcomas which prompted FISH studies confirming YWHAE rearrangement in 2 tumors. Genomic PCR confirmed the presence of BCOR exon 16 internal tandem duplication in the third case. Diffuse BCOR staining was strong in three and weak in one BCOR-rearranged high-grade endometrial stromal sarcoma while absent in the remaining four BCOR-rearranged tumors. BCOR staining was weakly positive in

Leiomyomas associated with hereditary leiomyomatosis and renal cell carcinoma syndrome and leiomyomas with bizarre nuclei often show overlapping morphological features, in particular cells with prominent eosinophilic nucleoli, perinucleolar halos, and eosinophilic cytoplasmic inclusions. Although hereditary leiomyomatosis and renal cell carcinoma syndrome is defined by fumarate hydratase (FH) germline mutations, resulting in S-(2-succino)-cysteine (2SC) formation, it is unknown whether leiomyomas with bizarre nuclei show similar alterations. In this study, we evaluated the morphology and FH/2SC immunoprofile of 31 leiomyomas with bizarre nuclei. DNA from tumor and normal tissues from 24 cases was subjected to massively parallel sequencing targeting 410 key cancer genes. Somatic genetic alterations were detected using state-of-the-art bioinformatics algorithms. No patient reported a personal history of renal neoplasia or cutaneous leiomyomas, but one had a family history of renal cell carcinoma while another had a family history of uterine leiomyomas. Aberrant FH/2SC expression was noted in 17 tumors (16 FH-negative/2SC-positive, 1 FH-positive/2SC-positive). On univariate analysis, staghorn vessels, eosinophilic cytoplasmic inclusions, diffuse distribution of prominent eosinophilic nucleoli with perinucleolar halos, and an 'alveolar pattern of edema' were associated with an abnormal immunoprofile, but only staghorn vessels remained significant on multivariate analysis. Massively parallel sequencing analysis (n=24) revealed that 13/14 tumors with aberrant FH/2SC immunoprofile harbored somatic FH somatic genetic alterations, including homozygous deletions (n=9), missense mutations coupled with loss of heterozygosity (n=3), and a splice site mutation (n=1), whereas no somatic FH mutations/deletions were found in tumors with normal immunoprofile (n=10; P

Almost all uterine mesenchymal tumours have been historically classified as either smooth muscle or endometrial stromal neoplasms. Recent application of molecular techniques has identified numerous lesions with distinctive genetic abnormalities and clinicopathological characteristics. Newly discovered uterine sarcoma subtypes include high-grade endometrial stromal sarcomas with BCOR genetic abnormalities, fibrosarcoma-like uterine sarcomas with NTRK rearrangements and COL1A-PDGFRB fusions, as well as undifferentiated uterine sarcomas with SMARCA4 mutations. Novel PLAG1 and PGR fusions have been identified in subsets of myxoid and epithelioid leiomyosarcomas. Some uterine tumours resembling ovarian sex-cord tumour harbour GREB1 and ESR1 rearrangements. Histological and immunophenotypical features as well as underlying genetic abnormalities defining these lesions are discussed.

Purpose: We examined whether prospective molecular characterization of advanced metastatic disease can reveal grade and/or histology-specific differences to inform diagnosis and facilitate enrollment onto clinical trials. Experimental Design: Patients with uterine sarcoma consented to a prospective study of next-generation sequencing (NGS). Clinical annotations were extracted from their medical record. Tumor and matched normal DNA were subjected to NGS, and the genomic landscape was explored for survival correlations and therapeutic targetability. Results: Tumors from 107 women were sequenced and included leiomyosarcoma (n = 80), high-grade non-leiomyosarcoma (n = 22), low-grade endometrial stromal sarcoma (LG-ESS, n = 4), and smooth muscle tumor of uncertain malignant potential (STUMP, n = 2). Genomic profiling influenced histologic diagnosis in three cases. Common uterine leiomyosarcoma alterations were loss-of-function mutations in TP53 (56%), RB1 (51%), and ATRX (31%). Homozygous deletions of BRCA2 were present in 5% of these patients. PTEN alteration frequency was higher in the metastases samples as compared with the primary samples. Genomes of low-grade tumors were largely silent, while 50.5% of high-grade tumors had whole-genome duplication. Two metastatic uterine leiomyosarcoma cases were hypermutated. Both had prolonged disease-free survival. Potentially actionable mutations were identified in 48 patients (45%), 8 (17%) of whom received matched therapy with 2 achieving clinical responses. Among patients with uterine leiomyosarcoma with somatic BRCA2 alterations, sustained partial responses were observed with PARP inhibitor–containing therapy. Discussion: Prospective genomic profiling can contribute to diagnostic precision and inform treatment selection in patients with uterine sarcomas. There was evidence of clinical benefit in patients with uterine leiomyosarcoma with somatic BRCA2 alterations treated with PARP inhibitors.

Genetic aberrations among uterine epithelioid leiomyosarcomas are unknown. Following identification of an index case with NR4A3-PGR fusion demonstrating monomorphic morphologic features, we interrogated additional uterine tumors demonstrating similar histology and sought to describe the morphologic and immunohistochemical characteristics of PGR-rearranged sarcomas. Targeted next-generation RNA sequencing was performed on RNA extracted from formalin-fixed paraffin-embedded tissue of the index case. Fluorescence in situ hybridization using custom probes flanking PGR and NR4A3 genes was applied to 17 epithelioid leiomyosarcomas, 6 endometrial stromal tumors, and 3 perivascular epithelioid cell tumors. NR4A3-PGR fusion (n=4) and PGR rearrangement (n=2) were detected in 6 (35%) epithelioid leiomyosarcomas. Median patient age was 45 years, and all presented with FIGO stage I or II tumors, 2 being alive with disease at 75 and 180 months. All tumors were centered in the cervical stroma or myometrium and consisted of cells with abundant eosinophilic cytoplasm (epithelioid), including many displaying dense intracytoplasmic inclusions (rhabdoid). Myxoid matrix and hydropic change imparted a microcystic growth pattern in 4 tumors. Five also showed a minor spindle cell component which was low-grade in 3, consisting of bland spindle cells with low mitotic activity. High-grade spindle cell morphology was seen in 2 tumors, exhibiting a storiform pattern of atypical spindle cells associated with brisk mitotic activity. Desmin, estrogen receptor, and progesterone receptor were positive in all 6 tumors, while CD10 and HMB45 were negative. PGR rearrangements define a genetic subset of epithelioid leiomyosarcomas with often biphasic morphology consisting of epithelioid and rhabdoid as well as spindle cell components.

Solid papillary carcinoma with reverse polarity (SPCRP) is a rare breast cancer subtype with an obscure etiology. In this study, we sought to describe its unique histopathologic features and to identify the genetic alterations that underpin SPCRP using massively parallel whole-exome and targeted sequencing. The morphologic and immunohistochemical features of SPCRP support the invasive nature of this subtype. Ten of 13 (77%) SPCRPs harbored hotspot mutations at R172 of the isocitrate dehydrogenase IDH2, of which 8 of 10 displayed concurrent pathogenic mutations affecting PIK3CA or PIK3R1. One of the IDH2 wild-type SPCRPs harbored a TET2 Q548* truncating mutation coupled with a PIK3CA H1047R hotspot mutation. Functional studies demonstrated that IDH2 and PIK3CA hotspot mutations are likely drivers of SPCRP, resulting in its reversed nuclear polarization phenotype. Our results offer a molecular definition of SPCRP as a distinct breast cancer subtype. Concurrent IDH2 and PIK3CA mutations may help diagnose SPCRP and possibly direct effective treatment. Cancer Res; 76(24); 7118–29. ©2016 AACR.

Whole slide imaging is Food and Drug Administration-approved for primary diagnosis in the United States of America; however, relatively few pathology departments in the country have fully implemented an enterprise wide digital pathology system enabled for primary diagnosis. Digital pathology has significant potential to transform pathology practice with several published studies documenting some level of diagnostic equivalence between digital and conventional systems. However, whole slide imaging also has significant potential to disrupt pathology practice, due to the differences in efficiency of manipulating digital images vis-a-vis glass slides, and studies on the efficiency of actual digital pathology workload are lacking. Our randomized, equivalency and efficiency study aimed to replicate clinical workflow, comparing conventional microscopy to a complete digital pathology signout using whole slide images, evaluating the equivalency and efficiency of glass slide to whole slide image reporting, reflective of true pathology practice workloads in the clinical setting. All glass slides representing an entire day’s routine clinical signout workload for six different anatomic pathology subspecialties at Memorial Sloan Kettering Cancer Center were scanned on Leica Aperio AT2 at ×40 (0.25 µm/pixel). Integration of whole slide images for each accessioned case is through an interface between the Leica eSlide manager database and the laboratory information system, Cerner CoPathPlus. Pathologists utilized a standard institution computer workstation and viewed whole slide images through an internally developed, vendor agnostic whole slide image viewer, named the “MSK Slide Viewer”. Subspecialized pathologists first reported on glass slides from surgical pathology cases using routine clinical workflow. Glass slides were de-identified, scanned, and re-accessioned in the laboratory information system test environment. After a washout period of 13 weeks, pathologists reported the same clinical workload using whole slide image integrated within the laboratory information system. Intraobserver equivalency metrics included top-line diagnosis, margin status, lymphovascular and/or perineural invasion, pathology stage, and the need to order ancillary testing (i.e., recuts, immunohistochemistry). Turnaround time (efficiency) evaluation was defined by the start of each case when opened in the laboratory information system and when the case was completed for that day (i.e., case sent to signout queue or pending ancillary studies). Eight pathologists participated from the following subspecialties: bone and soft tissue, genitourinary, gastrointestinal, breast, gynecologic, and dermatopathology. Glass slides signouts comprised of 204 cases, encompassing 2091 glass slides; and digital signouts comprised of 199 cases, encompassing 2073 whole slide images. The median whole slide image file size was 1.54 GB; scan time/slide, 6 min 24 s; and scan area 32.1 × 18.52 mm. Overall diagnostic equivalency (e.g., top-line diagnosis) was 99.3% between digital and glass slide signout; however, signout using whole slide images showed a median overall 19% decrease in efficiency per case. No significant difference by reader, subspecialty, or specimen type was identified. Our experience is the most comprehensive study to date and shows high intraobserver whole slide image to glass slide equivalence in reporting of true clinical workflows and workloads. Efficiency needs to improve for digital pathology to gain more traction among pathologists.

OBJECTIVE: To assess the rates and distribution of first recurrence in patients with FIGO stage IIIC1 endometrial cancer (EC) who did not undergo paraaortic dissection at surgical staging. METHODS: We retrospectively selected all (n=207) stage IIIC1 patients treated at a single institution from 5/1993–1/2017. Sites of first recurrence were identified, disease-free (DFS) and overall survival (OS) calculated, multivariate logistic regression performed to identify factors associated with recurrence. RESULTS: Three-year DFS and OS were 66.5% and 85.7%, respectively. The most common histology was endometroid (64.2%). Three-year DFS was 81% (SE+/−3.8%) endometrioid vs. 39.5% (SE+/−6.6%) non-endometrioid (P

Purpose: Advanced-stage endometrial cancers have limited treatment options and poor prognosis, highlighting the need to understand genetic drivers of therapeutic vulnerabilities and/or prognostic predictors. We examined whether prospective molecular characterization of recurrent and metastatic disease can reveal grade and histology-specific differences, facilitating enrollment onto clinical trials. Experimental Design: We integrated prospective clinical sequencing and IHC data with detailed clinical and treatment histories for 197 tumors, profiled by MSK-IMPACT from 189 patients treated at Memorial Sloan Kettering Cancer Center. Results: Patients had advanced disease and high-grade histologies, with poor progression-free survival on first-line therapy (PFS1). When matched for histology and grade, the genomic landscape was similar to that of primary untreated disease profiled by TCGA. Using multiple complementary genomic and mutational signature-based methods, we identified patients with microsatellite instability (MSI), even when standard MMR protein IHC staining failed. Tumor and matched normal DNA sequencing identified rare pathogenic germline mutations in BRCA2 and MLH1. Clustering the pattern of DNA copy-number alterations revealed a novel subset characterized by heterozygous losses across the genome and significantly worse outcomes compared with other clusters (median PFS1 9.6 months vs. 17.0 and 17.4 months; P = 0.006). Of the 68% of patients harboring potentially actionable mutations, 27% were enrolled to matched clinical trials, of which 47% of these achieved clinical benefit. Conclusions: Prospective clinical sequencing of advanced endometrial cancer can help refine prognosis and aid treatment decision making by simultaneously detecting microsatellite status, germline predisposition syndromes, and potentially actionable mutations. A small overall proportion of all patients tested received investigational, genomically matched therapy as part of clinical trials.

AIMS: The most common BRAF mutation in ovarian low-grade serous neoplasms (LGSNs) involves substitution of valine by glutamic acid at position 600 (V600E). Small studies have demonstrated high specificity of immunohistochemistry with mutation-specific monoclonal antibody VE1. We sought to investigate expression of VE1 protein in LGSNs and its correlation with BRAF mutation-associated histological features and BRAF mutation status. METHODS AND RESULTS: We reviewed pathology reports and available slides from ovarian serous borderline tumours (SBTs) and low-grade serous carcinomas (LGSCs) diagnosed between 2000-2012. VE1 immunohistochemistry was performed on formalin-fixed, paraffin-embedded tissue sections. Tumours with ≥50% positive cells were considered positive. Statistical analyses were performed using SPSS 24.0. Of 121 LGSNs, there were 73 SBTs, 8 SBTs with micropapillary features (mpSBT), and 40 LGSCs (22 primary, 18 metastatic). VE1 was positive in 52% (38/73) of SBTs and 9% (2/22) of primary LGSCs, and in none of the mpSBTs and metastatic LGSCs (p

Gastric-type cervical adenocarcinoma (GCA) is a human papillomavirus-unassociated, aggressive, chemorefractory tumor. Well-differentiated examples may exhibit bland morphologic appearances, which could potentially lead to misdiagnosis, particularly in limited material. We sought to characterize the morphologic features of GCA in surgical biopsy and cytology specimens. We identified patients with histologic diagnoses of GCA or minimal-deviation adenocarcinoma between 2004 and 2017. Available slides from biopsy, curettage, and cytology specimens were reviewed. Fifty-nine specimens (37 histology, 22 cytology) were reviewed from 23 patients, including histology specimens alone from 6 patients, cytology specimens alone from 4 patients, and both types of specimen from 13 patients. The median patient age was 52 yr (range, 29-83 yr). Biopsies showed well-to-moderately differentiated adenocarcinomas composed of cells with pale or foamy cytoplasm and well-defined cytoplasmic borders. Nuclei exhibited mild-to-moderate pleomorphism with small nucleoli. The diagnosis was challenging in a minority of biopsies in which neoplastic glandular epithelium was scant, fragmented, and/or well differentiated. Cytology slides showed single and crowded clusters of tumor cells with pale, foamy, and/or vacuolated cytoplasm and well-defined cytoplasmic borders. Nuclei were moderately pleomorphic, round to oval with one or more nucleoli. Of 20 submitted biopsies, GCA was suspected by the submitting pathologist in only 5 (25%) cases. Awareness of the morphologic features and use of confirmatory ancillary studies (eg, immunohistochemistry for markers of gastric differentiation and human papillomavirus testing) will allow accurate diagnosis of these aggressive tumors in biopsy and cytology specimens.

Tropomyosin receptor kinase (Trk) inhibitors have shown high response rates in patients with tumors harboring NTRK fusions. We identified 4 NTRK fusion-positive uterine sarcomas that should be distinguished from leiomyosarcoma and undifferentiated uterine sarcoma. NTRK rearrangements were detected by fluorescence in situ hybridization (FISH) and/or targeted RNA or DNA sequencing in 4 undifferentiated uterine sarcomas with spindle cell morphology. Because of histologic overlap with leiomyosarcoma, TrkA and pan-Trk immunohistochemistry was performed in 97 uterine leiomyosarcomas. NTRK1 and NTRK3 FISH was performed on tumors with TrkA or pan-Trk staining. We also performed whole transcriptome RNA sequencing of a leiomyosarcoma with TrkA expression and targeted RNA sequencing of 2 additional undifferentiated uterine sarcomas. FISH and/or targeted RNA or DNA sequencing in the study group showed TPM3-NTRK1, LMNA-NTRK1, RBPMS-NTRK3, and TPR-NTRK1 fusions. All tumors were composed of fascicles of spindle cells. Mitotic index was 7 to 30 mitotic figures per 10 high power fields; tumor necrosis was seen in 2 tumors. Desmin, estrogen receptor, and progesterone receptor were negative in all tumors, while pan-Trk was expressed in all tumors with concurrent TrkA staining in 3 of them. TrkA and/or pan-Trk staining was also seen in 6 leiomyosarcomas, but these tumors lacked NTRK fusions or alternative isoforms by FISH or whole transcriptome sequencing. No fusions were detected in 2 undifferentiated uterine sarcomas. NTRK fusion-positive uterine spindle cell sarcomas constitute a novel tumor type with features of fibrosarcoma; patients with these tumors may benefit from Trk inhibition. TrkA and pan-Trk expression in leiomyosarcomas is rare and does not correlate with NTRK rearrangement.

Our understanding of endometrial stromal sarcomas has evolved dramatically since their earliest descriptions from over a century ago. Initial studies focused on establishing the relationship between histological appearances of endometrial stromal sarcomas and their clinical outcomes. Studies performed in the last decade have uncovered several recurrent cytogenetic aberrations occurring in low- and high-grade endometrial stromal sarcomas. Low-grade endometrial stromal sarcomas bear close histopathological resemblance to proliferative-type endometrial stroma, and approximately half harbour t(7;17)(p15;q21) resulting in JAZF1-SUZ12 gene fusion. Less common JAZF1-PHF1, EPC1-PHF1, MEAF6-PHF1, and MBTD1-CXorf67 fusions have also been reported. The term 'high-grade endometrial stromal sarcoma' was recently re-introduced in the classification of endometrial stromal tumours after the discovery of t(10;17)(q22;p13) resulting in YWHAE-NUTM2A/B fusion and is associated with distinct morphological characteristics. This review highlights the evolution of endometrial stromal sarcoma classification schemes over time and describes the salient clinicopathological and molecular features of endometrial stromal nodule, low-grade endometrial stromal sarcoma, high-grade endometrial stromal sarcoma, and undifferentiated uterine sarcoma. It also describes the recent characterisation of endometrial stromal sarcoma with t(X;22)(p11;q13) resulting in ZC3H7B-BCOR fusion, a noteworthy entity due to its close histological resemblance to myxoid leiomyosarcoma. We also provide insights into common challenging scenarios encountered when assessing endometrial stromal lesions in daily surgical pathology practice.

YWHAE-rearranged high-grade endometrial stromal sarcoma (HG-ESS) is a rare, recently defined uterine sarcoma harboring t(10;17)(q22;p13) resulting in YWHAE-NUTM2A/B fusion. Chemotherapy sensitivity of metastatic YWHAE-rearranged HG-ESS is unknown. We reviewed the response to chemotherapy in women with YWHAE-rearranged HG-ESS to provide guidance for clinical management.We retrospectively identified patients diagnosed with YWHAE-rearranged HG-ESS who received treatment for metastatic disease at our institutions. Cytogenetics or fluorescence in situ hybridization were performed in all cases to confirm rearrangement and, in conjunction with histopathology, a diagnosis of YWHAE-rearranged HG-ESS. Patient demographics, tumor histology, surgical procedures, radiation therapy, chemotherapy and treatment responses were collected.Seven patients were identified with YWHAE-rearranged HG-ESS and met criteria for inclusion in this study. The median age at diagnosis was 45 (range 42-47). All patients had undergone hysterectomy with bilateral salpingo-oophorectomy. FIGO stage at diagnosis was IVB in four patients and a single patient each at stage IIIB, II or I. Median follow-up for the cohort was 27months (range 6-123). Six patients received anthracycline-based chemotherapy, with two of six achieving a complete radiologic response. One patient received gemcitabine and docetaxel, resulting in a partial response. For three patients who died from metastatic disease, survival from initial diagnosis was 33, 100 and 123months.For metastatic YWHAE-rearranged HG-ESS, prolonged disease control following diagnosis was seen, with notable responses to anthracycline-based therapy. This emphasizes the need for appropriate molecular testing of uterine mesenchymal malignancies and suggests that chemotherapy is an effective treatment option for metastatic YWHAE-rearranged HG-ESS.

Endometrial stromal sarcomas (ESS) are often underpinned by recurrent chromosomal translocations resulting in the fusion of genes involved in epigenetic regulation. To date, only YWHAE-NUTM2 rearrangements are associated with distinctive high-grade morphology and aggressive clinical behavior. We identified 3 ESS morphologically mimicking myxoid leiomyosarcoma of the uterus and sought to describe their unique histopathologic features and identify genetic alterations using next-generation sequencing. All cases displayed predominantly spindled cells associated with abundant myxoid stroma and brisk mitotic activity. Tumors involved the endometrium and demonstrated tongue-like myometrial infiltration. All 3 were associated with an aggressive clinical course, including multisite bony metastases in 1 patient, progressive peritoneal disease after chemotherapy in another, and metastases to the lung and skin in the last patient. All 3 ESS were found to harbor ZC3H7B-BCOR gene fusions by targeted sequencing and fluorescence in situ hybridization. On the basis of the review of these cases, we find that ESS with ZC3H7B-BCOR fusion constitutes a novel type of high-grade ESS and shares significant morphologic overlap with myxoid leiomyosarcoma.

Background: Solid papillary carcinoma with reverse polarization (SPCRP) is a rare breast cancer subtype, whose most striking morphologic feature is the presence of back-to-back columnar epithelial cells with nuclei situated in an apical rather than in the normal basal location. We sought to characterize the morphologic and genetic landscape of SPCRP and determine whether it represents a distinct subtype of breast cancer underpinned by highly recurrent disease-specific genetic alterations. Material and Methods: Archival sections of 13 SPCRPs were subjected to microdissection. DNA samples extracted from microdissected tumor and matched normal samples were subjected to whole exome sequencing (n = 2) on an Illumina HiSeq2000, and DNA samples from tumors were further subjected to targeted massively parallel sequencing (n = 1), SNaPshot profiling (n = 7) and/or Sanger sequencing. State-of-the-art bioinformatics methods were used to define somatic mutations. Non-malignant breast epithelial MCF10A cells with and without somatic PIK3CA H1047R knock-in were used to assess the functional impact of the mutations identified by sequencing of SPCRPs in two- and three-dimensional cell culture systems. Results: Ten of 13 (77%) SPCRPs were found to harbor IDH2 R172 hotspot mutations, and eight of these cases had concurrent pathogenic mutations affecting PIK3CA or PIK3R1, in particular PIK3CA H1047R hotspot mutations. Functional monolayer and three-dimensional cell culture studies demonstrated that IDH2 R172 and PIK3CA mutations constitute likely drivers of this tumor and contribute to its unusual nuclear polarization phenotype. Conclusions: Our results suggest that SPCRP is a distinct subtype of breast cancer underpinned by IDH2 hotspot mutations in conjunction with mutations affecting canonical genes of the PI3K pathway. Given that IDH2 hotspot mutations have not been described in breast cancer to date, these may be used as a diagnostic ancillary marker for SPCRPs. Furthermore, IDH2 mutations may serve as a potential therapeutic target in SPCRP patients with disseminated disease. Citation Format: Sarah Chiang, Britta Weigelt, Huei-Chi Wen, Salvatore Piscuoglio, Luciano G. Martelotto, Charlotte K Y Ng, Jörg Balss, Gabrielle Baker, Kimberly S. Cole, Andreas von Deimling, Julie M. Batten, Jonathan D. Marotti, Hwei-Choo Soh, Benjamin L. McCalip, Raymond S. Lim, Kalliopi P. Siziopikou, Randi Burke, Song Lu, Xiaolong Liu, Tarek Hammour, Edi Brogi, A John Iafrate, Jorge S. Reis-Filho, Stuart J. Schnitt. Solid papillary carcinoma with reverse polarization are driven by IDH2 and PI3K pathway mutations. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 138.