Targeting Galectin 3 illuminates its contributions to the pathology of uterine serous carcinoma.

BACKGROUND: Uterine serous cancer (USC) comprises around 10% of all uterine cancers. However, USC accounts for approximately 40% of uterine cancer deaths, which is attributed to tumor aggressiveness and limited effective treatment. Galectin 3 (Gal3) has been implicated in promoting aggressive features in some malignancies. However, Gal3's role in promoting USC pathology is lacking. METHODS: We explored the relationship between LGALS3 levels and prognosis in USC patients using TCGA database, and examined the association between Gal3 levels in primary USC tumors and clinical-pathological features. CRISPR/Cas9-mediated Gal3-knockout (KO) and GB1107, inhibitor of Gal3, were employed to evaluate Gal3's impact on cell function. RESULTS: TCGA analysis revealed a worse prognosis for USC patients with high LGALS3. Patients with no-to-low Gal3 expression in primary tumors exhibited reduced clinical-pathological tumor progression. Gal3-KO and GB1107 reduced cell proliferation, stemness, adhesion, migration, and or invasion properties of USC lines. Furthermore, Gal3-positive conditioned media (CM) stimulated vascular tubal formation and branching and transition of fibroblast to cancer-associated fibroblast compared to Gal3-negative CM. Xenograft models emphasized the significance of Gal3 loss with fewer and smaller tumors compared to controls. Moreover, GB1107 impeded the growth of USC patient-derived organoids. CONCLUSION: These findings suggest inhibiting Gal3 may benefit USC patients.

Sex Cord-Stromal Tumors of the Ovary: An Update and Review. Part I - Pure Ovarian Stromal Tumors.

In two separate reviews, we review the time-honored but still frequently challenging features of ovarian sex cord-stromal tumors, and also emphasize new developments including unusual morphologic appearances that, despite the relative rarity of many of the tumors, result in a disproportionate number of differential diagnostic problems, variant immunohistochemical profiles, and specific molecular and syndromic associations. These neoplasms are also of historical interest as current knowledge is still based in significant part on the contributions of 2 giants of gynecologic pathology, Dr Robert Meyer and Dr Robert E. Scully. In part I, we present the major clinical, pathologic, and genomic features of the pure ovarian stromal tumors including comments on differential diagnosis and briefly note significant historical contributions. In part II we will discuss pure sex cord and sex cord-stromal tumors.

Sex Cord-Stromal Tumors of the Ovary: An Update and Review. Part II - Pure Sex Cord and Sex Cord-Stromal Tumors.

We review the time honored but still frequently challenging features of ovarian sex cord-stromal tumors and also emphasize new developments, including unusual morphologic appearances that, despite the relative rarity of many of the tumors, result in a disproportionate number of differential diagnostic problems, variant immunohistochemical profiles, and specific molecular and syndromic associations. These neoplasms are also of historical interest as current knowledge is still based in significant part to the contributions of 2 giants of gynecologic pathology, Dr Robert Meyer and Dr. Robert E. Scully. In part I, we reviewed the pure ovarian stromal tumors. Now, in part II, we present the major clinical, pathologic, and genomic features of pure sex cord and sex cord-stromal tumors.

Outcomes in ovarian Sertoli-Leydig cell tumor: A report from the International Pleuropulmonary Blastoma/DICER1 and Ovarian and Testicular Stromal Tumor Registries.

OBJECTIVE: Sertoli-Leydig cell tumors (SLCTs) are rare sex cord-stromal tumors, representing <0.5% of all ovarian tumors. We sought to describe prognostic factors, treatment and outcomes for individuals with ovarian SLCT. METHODS: Individuals with SLCT were enrolled in the International Pleuropulmonary Blastoma/DICER1 Registry and/or the International Ovarian and Testicular Stromal Tumor Registry. Medical records were systematically abstracted, and pathology was centrally reviewed when available. RESULTS: In total, 191 participants with ovarian SLCT enrolled, with most (92%, 175/191) presenting with FIGO stage I disease. Germline DICER1 results were available for 156 patients; of these 58% had a pathogenic or likely pathogenic germline variant. Somatic (tumor) DICER1 testing showed RNase IIIb hotspot variants in 97% (88/91) of intermediately and poorly differentiated tumors. Adjuvant chemotherapy was administered in 40% (77/191) of cases, and among these, nearly all patients received platinum-based regimens (95%, 73/77), and 30% (23/77) received regimens that included an alkylating agent. Three-year recurrence-free survival for patients with stage IA tumors was 93.6% (95% CI: 88.2-99.3%) compared to 67.1% (95% CI: 55.2-81.6%) for all stage IC and 60.6% (95% CI: 40.3-91.0%) for stage II-IV (p < .001) tumors. Among patients with FIGO stage I tumors, those with mesenchymal heterologous elements treated with surgery alone were at higher risk for recurrence (HR: 74.18, 95% CI: 17.99-305.85). CONCLUSION: Most individuals with SLCT fare well, though specific risk factors such as mesenchymal heterologous elements are associated with poor prognosis. We also highlight the role of DICER1 surveillance in early detection of SLCT, facilitating stage IA resection.

Gynecologic Pathology Journal Club: A 2-year, Worldwide Virtual Learning Experience With a Focus on Mentorship and Inclusion.

Journal clubs (JCs) are a common format used in teaching institutions to promote trainee engagement and develop skills in seeking out evidence-based medicine and critically evaluating literature. Digital technology has made JC accessible to worldwide audiences, which allows for increased inclusion of globally diverse presenters and attendees. Herein we describe the experience of the first 2 years of a virtual gynecologic pathology JC designed with the goal of providing mentorship and increasing inclusivity. JC began in a virtual format in April 2020 in response to the need for remote learning during the coronavirus disease 2019 pandemic. Each JC had 1 moderator, lasted 1 hour, featured up to 3 trainees/early-career pathologists, and covered articles on gynecologic surgical pathology/cytopathology. Trainees were recruited through direct contact with moderators and advertising through social media (eg, Twitter). A template was used for all presentations, and before presenting, live practice sessions were conducted with the moderator providing constructive feedback and evaluations were provided to presenters and attendees for feedback. Recordings of the meetings were made publicly available after the event through YouTube, a society website, and emails to registrants. Fifty-nine presenters participated, covering 71 articles. Most were trainees (53/59; 89%) from North America (33/59; 56%), with additional presenters from Asia (14/59; 24%), Australia/Oceania (5/59; 8%), Africa (4/59; 7%), and Europe (3/59; 5%). An average of 20 hours were spent per month by moderators on the selection of papers, meeting preparation, and provision of mentorship/feedback. Live events had a total of 827 attendees, and 16,138 interactions with the recordings were noted. Among those who self-identified on provided surveys, the attendees were most commonly from Europe (107/290; 37%) and were overwhelmingly practicing pathologists (275/341; 81%). The experience, including mentorship, format, and content, was positively reviewed by attendees and presenters. Virtual JC is an inclusive educational opportunity to engage trainees and early-career pathologists from around the world. The format allowed for the JC to be widely viewed by attendees from multiple countries, most being practicing pathologists. Based on feedback received, virtual JC appears to expand the medical knowledge of the attendees and empower presenters to develop their expertise and communication skills.

Proposal of Novel Binary Grading Systems for Cervical Squamous Cell Carcinoma.

We compared grading systems and examined associations with tumor stroma and survival in patients with cervical squamous cell carcinoma. Available tumor slides were collected from 10 international institutions. Broders tumor grade, Jesinghaus grade (informed by the pattern of tumor invasion), Silva pattern, and tumor stroma were retrospectively analyzed; associations with overall survival (OS), progression-free survival (PFS), and presence of lymph node metastases were examined. Binary grading systems incorporating tumor stromal changes into Broders and Jesinghaus grading systems were developed. Of 670 cases, 586 were reviewed for original Broders tumor grade, 587 for consensus Broders grade, 587 for Jesinghaus grade, 584 for Silva pattern, and 556 for tumor stroma. Reproducibility among grading systems was poor (κ = 0.365, original Broders/consensus Broders; κ = 0.215, consensus Broders/Jesinghaus). Median follow-up was 5.7 years (range, 0-27.8). PFS rates were 93%, 79%, and 71%, and OS rates were 98%, 86%, and 79% at 1, 5, and 10 years, respectively. On univariable analysis, original Broders ( P < 0.001), consensus Broders ( P < 0.034), and Jesinghaus ( P < 0.013) grades were significant for OS; original Broders grade was significant for PFS ( P = 0.038). Predictive accuracy for OS and PFS were 0.559 and 0.542 (original Broders), 0.542 and 0.525 (consensus Broders), 0.554 and 0.541 (Jesinghaus grade), and 0.512 and 0.515 (Silva pattern), respectively. Broders and Jesinghaus binary tumor grades were significant on univariable analysis for OS and PFS, and predictive value was improved. Jesinghaus tumor grade ( P < 0.001) and both binary systems (Broders, P = 0.007; Jesinghaus, P < 0.001) were associated with the presence of lymph node metastases. Histologic grade has poor reproducibility and limited predictive accuracy for squamous cell carcinoma. The proposed binary grading system offers improved predictive accuracy for survival and the presence of lymph none metastases.

Leiomyoma-like Morphology in Metastatic Uterine Inflammatory Myofibroblastic Tumors.

Uterine inflammatory myofibroblastic tumors (IMTs) are rare mesenchymal neoplasms that frequently harbor ALK gene rearrangements and have a low risk of metastasis. We reported 3 of these tumors mimicking the appearance of leiomyoma in their recurrence. These patients were 34, 43, and 45 years old. Two uterine tumors demonstrated classic morphology, with combined myxoid, compact fascicular, and hyalinized patterns and spindled cells with bipolar cytoplasmic processes, moderate atypia, and lymphoplasmacytic inflammatory infiltrates. The third had a "leiomyoma-like" appearance, with fascicles of plump spindled cells and a sparse lymphoplasmacytic infiltrate. ALK immunohistochemistry was positive in all the tumors, and all demonstrated ALK rearrangements using fluorescence in situ hybridization (n = 2) and/or RNA sequencing (n = 2). Two classic IMTs recurred at 3 and 50 months in the lung and abdomen, respectively, and recurrent tumors had a "leiomyoma-like" appearance, with 0 and 1 mitosis per 10 high-power fields, no inflammation in 1, and a sparse lymphocytic infiltrate in the other. ALK was positive in both tumors; 1 with available tissue showed an IGFBP5::ALK fusion using RNA sequencing. The third patient, who had a "leiomyoma-like" uterine tumor, experienced multiple recurrences, first in the abdomen at 100 months showing a similar appearance. Subsequent recurrence at 105 months showed transmural invasion of the sigmoid colon and a similar microscopic appearance but with the addition of infiltrative borders, moderate cellularity, mild-to-moderate atypia, and 10 mitoses per 10 high-power fields. Both recurrences were positive for ALK, and RNA sequencing revealed the same ACTG2::ALK fusion transcript identified in the primary tumor. The patient was treated with crizotinib, resulting in prolonged clinical remission, with no evidence of disease at 168 months from the initial surgery. Although "leiomyoma-like" uterine IMTs have been recently described, to our knowledge, this is the first report of recurrence of these tumors and the first report of a "leiomyoma-like" appearance in the recurrences of conventional uterine IMTs. A low threshold for performing ALK immunohistochemistry on recurrent uterine tumors can identify patients who may benefit from tyrosine kinase inhibitors.

Extensive versus focal lymphovascular invasion in squamous cell carcinoma of the cervix: A comprehensive international, multicenter, retrospective clinicopathologic study.

OBJECTIVE: We evaluated clinicopathologic parameters of patients with cervical squamous cell carcinoma (SCC) who were treated with initial surgical management and assessed their relation to survival outcomes. Specifically, we evaluated the relation between extent of lymphovascular invasion (LVI) and survival outcomes. METHODS: All available tumor slides from patients with initially surgically treated cervical SCC were collected from 10 institutions and retrospectively analyzed. Standard clinicopathological parameters, tumor stroma, and extent of LVI were assessed (focal: <5 spaces, extensive: ≥5 spaces). PFS and OS were evaluated using Kaplan-Meier methodology. Univariable and multivariable Cox proportional hazards models were created to determine prognostic survival-related risk factors. RESULTS: A total of 670 tumor samples were included in the analysis. Median age at diagnosis was 47 years (IQR: 38-60), 457 patients (72%) had a 2018 International Federation of Gynecology and Obstetrics (FIGO) stage I tumor, and 155 tumors (28%) were flat and/or ulcerated. There were 303 nonkeratinizing tumors (51%), 237 keratinizing tumors (40%), and 356 histologic grade 2 tumors (61%). Quantifiable LVI was present in 321 cases (51%; 23% focal and 33% extensive). On multivariable analysis for PFS, extensive and focal LVI had worse outcomes compared to negative LVI (HR: 2.38 [95% CI: 1.26-4.47] and HR: 1.54 [95% CI: 0.76-3.11], respectively; P = 0.02). The difference did not reach statistical significance for OS. CONCLUSION: Presence of LVI is a prognostic marker for patients with cervical SCC. Quantification (extensive vs. focal vs. negative) of LVI may be an important biomarker for oncologic outcome.

BAP1 and Claudin-4, But Not MTAP, Reliably Distinguish Borderline and Low-grade Serous Ovarian Tumors From Peritoneal Mesothelioma.

Peritoneal mesothelioma (PM) and serous neoplasms can be difficult to differentiate, particularly in small biopsies. BRCA1-associated protein 1 (BAP1) is expressed in benign tissues, but over 50% of PMs demonstrate complete loss of nuclear expression. Claudin-4, a tight junction protein, is expressed in most epithelial tumors but not in mesotheliomas. Methylthioadenosine phosphorylase (MTAP) is frequently co-deleted with cyclin-dependent kinase inhibitor 2a in mesotheliomas. These markers have proven useful in separating mesothelioma from its mimics, particularly when tumors are pleural based. In the peritoneum, BAP1 loss has been rarely reported in high-grade serous carcinomas, but overall, these markers have been minimally evaluated in ovarian serous borderline tumors and low-grade serous carcinomas. Thus, we assessed the utility of BAP1, claudin-4, and MTAP in the differential diagnosis of PM and low-grade serous neoplasms. Eighteen PM (16 epithelioid, 1 biphasic, and 1 sarcomatous), 24 low-grade serous carcinomas, and 25 serous borderline tumors were stained for BAP1, claudin-4, and MTAP. Loss of BAP1 nuclear expression was observed in 12 (67%) PM (11 epithelioid, 1 biphasic) but was retained in all serous tumors. Claudin-4 was positive in all serous tumors and negative in all PM. Complete loss of cytoplasmic MTAP was noted in 3 (17%) PMs and 1 (4%) serous borderline tumor, while all low-grade serous carcinomas showed retained expression. BAP1 loss reliably distinguishes PM from serous tumors, although it lacks sensitivity. Claudin-4 is a reliable marker to exclude PM. MTAP loss may occur in both PM and serous tumors, and thus is not useful in distinguishing these entities.

Cystic Walthard Nests of the Peritoneal Diaphragm: A Report of 3 Cases of a Common Process at an Unusual Site and Occurring in Patients With Endometriosis.

Nests of cells resembling urothelium, eponymously named "Walthard nests," are well-known incidental findings over the fallopian tube and occasionally undergo cystification resulting in clinical detection and surgical removal. Only rarely is this process noted outside the pelvic peritoneum. Herein we describe cystic Walthard nests occurring in the diaphragmatic peritoneum of three patients (aged 25, 36, and 39 yr) undergoing surgical evaluation for presumed endometriosis. In each case, small pearly white nodules on the diaphragmatic peritoneum were noted and biopsied. Microscopic examination revealed cystic spaces filled with pale eosinophilic secretion. The cysts were lined mostly by stratified transitional cells with pale eosinophilic to focally clear cytoplasm. Umbrella cells were focally present in all cases, and 1 showed focal glandular differentiation resembling cystitis glandularis. In areas, the epithelial cells became flattened and attenuated and nuclei were bland. By immunohistochemistry, all were positive for GATA3, cytokeratin 7, and BEREP4 and negative for cytokeratin 20, estrogen receptor, and WT-1. Walthard nests can rarely occur outside the pelvic peritoneum where they may be noted incidentally during surgery for other indications. This should be readily distinguished pathologically from other peritoneal lesions but lack of significant prior comment of them occurring on the diaphragm may result in diagnostic difficulty.

Patterns of spread and genetic alterations of primary endometrioid carcinomas of the ovary.

OBJECTIVE: The primary objective was to characterize the rate of lymph node involvement in a cohort of patients with primary ovarian endometrioid adenocarcinoma. Additionally, we sought to quantify the recurrence rate, genetic alterations, and impact of lymphadenectomy on survival in this group of patients. METHODS: Patients diagnosed with primary endometrioid adenocarcinoma of the ovary without synchronous carcinomas of the female genital tract between 2012 and 2021 were identified. Demographic and disease-related data were collected from pathology reports and clinical records. Kaplan-Meier survival analysis using log rank test and Cox regression was performed. RESULTS: Sixty-three patients met inclusion criteria. Median age was 60 (range 22-90) years. Histologic grade was 1 in 20 (32%), 2 in 27 (43%), and 3 in 16 (25%) tumors. International Federation of Gynecology and Obstetrics (FIGO) stage after surgery included IA/B (n=20, 32%), IC (n=23, 37%), II (n=16, 25%), and III (n=4, 6%). Forty-one (65%) patients had pelvic and 33 (52%) had both pelvic and para-aortic lymphadenectomy. All assessed lymph nodes were negative for metastatic carcinoma. No patients with clinically pelvis-confined disease had tumors upstaged by either lymphadenectomy or omentectomy. Twenty-eight patients (44%) had germline mutational status documented; two had a germline BRCA mutation, confirmed to be pathogenic by molecular studies. Complete staging did not significantly impact progression free or overall survival, after adjusting for age and histologic grade in a Cox proportional hazards model. The recurrence rate was 15% for patients with grade 1 endometrioid carcinoma, 7% for grade 2, and 31% for grade 3, respectively. CONCLUSION: There were no lymph node metastases in patients with comprehensively staged primary endometrioid ovarian carcinoma. Staging did not impact survival and may be omitted, regardless of grade. Germline BRCA mutations are rare in ovarian endometrioid carcinoma compared with reported rates in high-grade serous carcinomas.

An Unusual Case of a Scrotal Porocarcinoma and Review of the Literature.

ABSTRACT: Porocarcinomas are rare tumors derived from the acrosyringium and eccrine ducts, which most commonly occur on the lower extremities or head and neck region in older adults. Microscopically, they invariably demonstrate continuity with the epithelium, showing downgrowth of broad anastomosing bands with more infiltrative intradermal cords and nests of pleomorphic tumor cells with ductal lumina; an associated poroma may also be seen. We report an unusual case of a porocarcinoma arising on the scrotum of a 55-year-old man. Because of the extraordinary location and the presence of keratinizing squamous differentiation, distinction from a squamous cell carcinoma was particularly challenging. Close examination revealed the presence of a co-existing poroma, and immunohistochemistry revealed loss of YAP1 with diffuse nuclear expression of NUT in both the porocarcinoma and poroma components. This finding is particularly suggestive of a YAP1::NUTM1 fusion which has been reported to be highly specific for poroid neoplasms. Distinction of porocarcinoma from its mimics is important due to the frequent aggressive behavior of this neoplasm.

Myelodysplastic/myeloproliferative neoplasms-unclassifiable with isolated isochromosome 17q represents a distinct clinico-biologic subset: a multi-institutional collaborative study from the Bone Marrow Pathology Group.

Classification of myeloid neoplasms with isolated isochromosome i(17q) [17p deletion with inherent monoallelic TP53 loss plus 17q duplication] is controversial. Most cases fall within the WHO unclassifiable myelodysplastic/myeloproliferative neoplasms (MDS/MPN-U) category. The uniformly dismal outcomes warrant better understanding of this entity. We undertook a multi-institutional retrospective study of 92 adult MDS/MPN-U cases from eight institutions. Twenty-nine (32%) patients had isolated i(17q) [MDS/MPN-i(17q)]. Compared to MDS/MPN without i(17q), MDS/MPN-i(17q) patients were significantly younger, had lower platelet and absolute neutrophil counts, and higher frequency of splenomegaly and circulating blasts. MDS/MPN-i(17q) cases showed frequent bilobed neutrophils (75% vs. 23%; P = 0.03), hypolobated megakaryocytes (62% vs. 20%; P = 0.06), and a higher frequency of SETBP1 (69% vs. 5%; P = 0.002) and SRSF2 (63% vs. 5%; P = 0.006) mutations that were frequently co-existent (44% vs. 0%; P = 0.01). TP53 mutations were rare. The mutation profile of MDS/MPN-U-i(17q) was similar to other myeloid neoplasms with i(17q) including atypical chronic myeloid leukemia, chronic myelomonocytic leukemia, myelodysplastic/myeloproliferative neoplasm with ring sideroblasts and thrombocytosis, myelodysplastic syndrome and acute myeloid leukemia, with frequent concomitant SETBP1/SRSF2 mutations observed across all the diagnostic entities. Over a median follow-up of 52 months, patients with MDS/MPN-i(17q) showed a shorter median overall survival (11 vs. 28 months; P < 0.001). The presence of i(17q) retained independent poor prognostic value in multivariable Cox-regression analysis [HR 3.686 (1.17-11.6); P = 0.026] along with splenomegaly. We suggest that MDS/MPN-i(17q) warrants recognition as a distinct subtype within the MDS/MPN-U category based on its unique clinico-biologic features and uniformly poor prognosis.

Sclerosing stromal tumour: a clinicopathological study of 100 cases of a distinctive benign ovarian stromal tumour typically occurring in the young.

AIMS: Since the sclerosing stromal tumour (SST) of the ovary was first described in 1973, few studies have expanded upon its histological features or overlap with other tumours. We thus investigate these aspects based on our experience with 100 cases. METHODS AND RESULTS: The patients, 14 of whom were pregnant, ranged from 12 to 63 years (median = 26 years). Ten patients had hormonal manifestations (seven oestrogenic, three androgenic). Bilateral ovarian involvement was present in two cases. Size ranged from 1 to 23 cm (mean = 8.4 cm). Most tumours were solid and white with focal yellow areas; oedema with cystic degeneration (seen in 25 cases) resulted in eight being predominantly cystic. On microscopic examination, alternating cellular and paucicellular areas (pseudolobulation) were prominent in 94 cases but seen to a limited degree in the remaining neoplasms. Admixed spindled and luteinised cells were present in all tumours, but 13 demonstrated mainly spindled cells and 19 demonstrated mainly lutein cells; 14 of the latter were from pregnant patients. The stroma was typically oedematous or collagenous, but in 14 cases was prominently hyalinised and, in four, myxoid. Prominent vascularity was present in most cases. The mitotic rate ranged from 0 to 8/10 high-power fields (HPF), but most demonstrated <1/10 HPF. CONCLUSIONS: The differential diagnosis of SST is broad, including fibromas, thecomas, solitary fibrous tumours, pregnancy luteomas, myxomas, other ovarian sex cord-stromal tumours with sclerosis and, rarely, Krukenberg tumours. Strict adherence to the requirement of pseudolobulation, prominent (usually ectatic) vessels, and lutein cells and fibroblasts admixed in a jumbled manner, will distinguish the neoplasm from others in the differential.

Mutational spectrum in clinically aggressive low-grade serous carcinoma/serous borderline tumors of the ovary-Clinical significance of BRCA2 gene variants in genomically stable tumors.

OBJECTIVE: The mutational spectra of low-grade serous carcinomas (LGSCs) and serous borderline tumors (SBTs) of the ovary are poorly characterized. We present 17 cases of advanced or recurrent LGSC/SBT patients who underwent molecular profiling. METHODS: Thirteen LGSCs and four SBTs underwent targeted gene panel testing by massively parallel sequencing. Microsatellite stability and tumor mutation burdens (TMBs) were determined based on panel sequencing data. RESULTS: The mean TMB was 5.2 mutations/megabase (range 3-10) in 14 cases. Twelve of twelve (12/12) cases were microsatellite stable. Clear driver mutations were identified in 11 cases, namely KRAS (5/17), BRAF (2/17), NRAS (2/17) and ERBB2 (2/17). Five cases harbored BRCA2 alterations (allele fractions: 44-51%), including two classified as likely benign/benign variants, and three classified as variants of uncertain significance (VUSs), with two variants being confirmed to be germline. The three BRCA2 VUSs were missense variants that were assessed to be of unlikely clinical significance, based on family cancer history and expected impact on protein function. Two patients received PARP inhibitors during their disease course, with neither of the patients demonstrating appreciable response. CONCLUSIONS: The mutational spectra in 17 clinically aggressive SBT/LGSC cases demonstrate genomically stable tumors, frequently driven by the RTK/RAS/MAPK pathway. While BRCA2 variants were identified, our data demonstrate BRCA2 gene variants are at most VUSs and of dubious clinical significance, in contrast to disease-associated BRCA1/2 variants that may be identified in high-grade serous carcinoma. Germline testing and PARP inhibitors are thus expected to provide limited benefit to patients with LGSC/SBTs.

HYPERsol: High-Quality Data from Archival FFPE Tissue for Clinical Proteomics.

Massive formalin-fixed, paraffin-embedded (FFPE) tissue archives exist worldwide, representing an invaluable resource for clinical proteomics research. However, current protocols for FFPE proteomics lack standardization, efficiency, reproducibility, and scalability. Here we present high-yield protein extraction and recovery by direct solubilization (HYPERsol), an optimized workflow using ultrasonication and S-Trap sample processing that enables proteome coverage and quantification from FFPE samples comparable to that achieved from flash-frozen tissue (average R = 0.936). When applied to archival samples, HYPERsol resulted in high-quality data from FFPE specimens in storage for up to 17 years, and may enable the discovery of new immunohistochemical markers.

Embryoid Bodies and Related Proliferations in Ovarian Germ Cell Tumors.

We investigated the frequency and associated pathology of embryoid bodies in ovarian tumors by evaluating neoplasms in which they are known to occur: 100 immature teratomas, 125 malignant mixed germ cell tumors, and 6 polyembryomas. Three immature teratomas contained a single relatively well-formed embryoid body, whereas these and 11 others showed foci we categorized as embryoid body remnants consisting of microscopic aggregates of embryonal or yolk sac-type epithelium associated with spaces consistent with yolk sac or amniotic cavity but lacking a classic embryoid body structure. Teratomas with these foci were all high grade. A well-formed embryoid body was found in only 1 malignant mixed tumor, but embryoid body remnants were present in 25%, invariably associated with foci of immature teratoma (100%) and often with yolk sac tumor (97%), embryonal carcinoma (35%), or both (32%). These foci usually took the form of round to oval aggregates, often well-circumscribed, for which the term "polyembryoma background" has been proposed. The polyembryomas were typically grossly hemorrhagic and occurred in patients from 9 to 43 years of age. The embryoid bodies in them generally grew in lobules within an edematous to occasionally myxoid stroma. Four tumors contained liver-like cells, 4 numerous glands likely recapitulating the allantois, 3 syncytiotrophoblast cells, 2 prominent cysts, and 2 striking vascular proliferations. This study indicates that (1) typical embryoid bodies are rare in immature teratomas but about 14% of them have embryoid body remnants. (2) Embryoid body remnants are seen in 25% of malignant mixed germ cell tumors with a teratomatous component and often proliferate to form yolk sac tumor and embryonal carcinoma. (3) Well-formed embryoid bodies growing in a confluent manner (polyembryoma) are rare, and minor foci of teratoma, yolk sac tumor, or embryonal carcinoma are almost always present, indicating that these are fundamentally malignant mixed germ cell tumors but the polyembryoma component is dominant and distinctive which, in our opinion, justifies its own nomenclature. (4) Embryoid bodies are not a feature of other germ cell tumors.

Transitioning From Trainee to Practicing Pathologist: A Prospective Multi-institutional Survey of the Challenges Early Career Anatomic Pathologists Encounter When Entering Independent Practice.

CONTEXT.­: Pathology training programs generally prepare graduates well for the workforce, but there may be other aspects to navigating a job that make the transition from being a trainee to a practicing pathologist challenging. OBJECTIVE.­: To identify perceived challenges of independent practice for early career pathologists and assess how these impressions evolve throughout their first year. DESIGN.­: A survey was distributed to 12 anatomic pathology fellows from 4 institutions near the end of their final training year, and 6 months and 1 year after starting their first job. The surveys queried participants' comfort level with signing out cases independently and interacting with colleagues/trainees via Likert attitude scale questions with free-text segments to elaborate on challenges experienced. RESULTS.­: The response rate to all 3 surveys was 100%. Confidence and comfort level with different aspects of independent sign-out increased incrementally over time. Main challenges encountered at 6 months included a high case load, signing out cases in areas outside of their subspecialty, time management, balancing teaching while signing out, laboratory issues, and developing relationships with clinicians. At 12 months, main challenges included time management, high case load, understaffing, laboratory issues, and signing out cases in areas outside of their subspecialty. CONCLUSIONS.­: This study identified real-time challenges faced by those adjusting to their first year of independent practice. By gaining a better understanding of the factors that make this transition challenging, we can find tailored ways to support our early career pathologists.

Large and Extensive Multilocular Peritoneal Inclusion Cysts Lack Genomic Alterations and Follow an Indolent Clinical Course Despite Rare Recurrences.

Peritoneal inclusion cysts (PICs) are unilocular or multilocular cystic lesions lined by bland mesothelial cells. While most are small and localized, rare examples may be large or multifocal with diffuse peritoneal involvement, causing clinical and even pathologic concern for malignancy. We examined 20 PIC, including 8 large solitary and 12 multifocal lesions. Solitary PIC were found in 7 female and 1 male patients ranging from 19 to 55 (median: 37) years. Expanded collagenous (n=2) or edematous (n=1) areas were occasionally seen in the septae, and 1 had microscopic foci of myxoid stroma. Four had hobnail cells, and 1 had minor areas of papillary mesothelial hyperplasia. Multifocal PICs occurred in 9 female and 3 male patients ranging from 26 to 80 (median: 53) years. Three showed extensive associated fibrosis with entrapment of preexisting adipose tissue, 2 had areas resembling granulation tissue, and 3 had scattered foci of myxoid stroma. Hobnail cells were present in 9, papillary mesothelial hyperplasia in 2, entrapped single cells in 1, and 2 had areas resembling adenomatoid tumors. Two of the multifocal PICs had limited local recurrences at 18 and 21 months. No patients died of disease. Clonal alterations were not identified in any of the tested PICs (mutational and fusion analysis in 5, chromosomal microarray in 1). Despite limited local recurrences, we demonstrate that even large and multifocal PICs may lack identifiable genomic alterations and are associated with benign outcomes.