Clinicopathologic and Molecular Characteristics of Mesonephric Adenocarcinoma Arising From the Uterine Body. Am J Surg Pathol. 2019;43:12-25. [PMID: 29189288 DOI: 10.1097/PAS.0000000000000991]

Molecular characterization of ovarian mesonephric-like adenocarcinoma: Insights from single-cell RNA sequencing and mitochondrial metabolism

Objectives

Ovarian mesonephric-like adenocarcinoma (MLA) is a rare malignancy with limited understanding of its molecular features and therapeutic vulnerabilities. Although similar to uterine MLA, its unique characteristics remain undefined. This study aimed to characterize ovarian MLA using single-cell RNA sequencing (scRNA-seq) and compare it with high-grade serous ovarian cancer (HGSOC).

Methods

We analyzed the cellular and molecular heterogeneity of an ovarian MLA sample using scRNA-seq. Differential gene expression and pathway analyses were performed to identify unique molecular signatures and therapeutic targets. HGSOC scRNA-seq datasets were used for comparative analysis.

Results

Ovarian MLA demonstrated reduced heterogeneity, with a predominance of epithelial cells compared to HGSOC. Transcriptomic profiling revealed an upregulation of mitochondrial metabolism and lipid biosynthesis genes, indicating a metabolic shift toward oxidative phosphorylation. Gene enrichment and protein-protein interaction analyses identified distinct pathways, including mitochondrial biogenesis and dynamics, suggesting mitochondrial reprogramming.

Conclusions

This study provides the first scRNA-seq-based molecular characterization of ovarian MLA, differentiating it from HGSOC. Findings suggest potential therapeutic avenues, with a proposed combination therapy targeting MAP kinase and PI3K/AKT/mTOR pathways. Validation in larger cohorts is necessary for clinical application.

Mesonephric and Mesonephric-like Adenocarcinomas of the Gynecologic Tract: A Case Series and a Review of the Literature

We sought to present and describe all cases of mesonephric adenocarcinoma (MNAC) and mesonephric-like adenocarcinomas (MLAs) at our institution. These cancers are rare, morphologically similar tumors of the female reproductive tract. In this case series, we present 13 new cases of MNAC/MLA that were identified at St. Luke's University Health Network from 2016 to 2024. Demographics, clinical characteristics, and pathologic findings were collected from chart review. There were 6 uterine, 5 ovarian, and 2 cervical MNAC/MLAs. At presentation, more than half of the patients presented at early stages with 7, 2, 3, and 1 diagnosed at stages I, II, III, and IV, respectively. All patients underwent upfront surgical resection and were recommended adjuvant therapy. One patient declined adjuvant treatment. At the time of writing, 9 of 13 patients have completed treatment and have no evidence of disease, 1 is alive with disease, 1 is currently undergoing treatment, and 2 died of disease. Median overall survival (OS) was 15 mo (95% CI: 2.2-27.8 mo). Current literature regarding MNACs/MLAs suggests an overall poor prognosis, with the majority presenting at advanced stages. This case series describes patients diagnosed with early-stage disease and reports on their histopathology, treatment regimens, and clinical outcomes. The majority of these patients are without recurrence after upfront treatment. Continued surveillance of these patients to determine long-term outcomes is necessary to further elucidate overall prognosis.

Identifying mesonephric-like adenocarcinoma of the endometrium by combining SOX17 and PAX8 immunohistochemistry

AIMS

Mesonephric-like adenocarcinoma (MLA) of the endometrium or ovary is a rare but distinct endometrial carcinoma which has a combination of characteristic morphological, immunohistochemical (IHC) and molecular features. SOX17 has been recently identified as a highly sensitive and specific marker for endometrial and ovarian carcinomas. In this study, we aimed to investigate SOX17 expression in MLA together with other IHCs to differentiate MLAs from other endometrial carcinomas.

METHODS

Seventeen previously diagnosed endometrial/ovarian MLAs were collected, and multiple IHCs were performed. Additionally, we performed SOX17, PAX8 and ER on tissue microarrays (TMAs) composed of 652 endometrial carcinomas from 2012 to 2015 when MLA diagnostic criteria were not established.

RESULTS

All 17 MLAs showed diffuse strong positive PAX8, negative ER and variable TTF1/GATA3 staining. Notably, all MLAs showed negative (n = 10) or focal weak/moderate (n = 7) staining for SOX17, which is more diffuse and stronger than PAX8 in other endometrial carcinoma subtypes. This finding prompted us to screen TMAs with 652 endometrial carcinomas diagnosed before MLA by an approach of combined SOX17 and PAX8 IHCs, and 14 cases with positive PAX8 but negative/focal weak SOX17 were identified. We further studied the 14 cases by examining morphology and performing additional IHCs (TTF1, GATA3, ER and CD10) and would classify seven (50%) of them as MLAs based on morphological features and positive CD10, TTF1 and/or GATA3 staining.

CONCLUSION

Our results suggest that a combination of SOX17 and PAX8 IHCs would aid in diagnosing MLA if the results show strong positive PAX8, but negative SOX17.

The Clinical Characteristics and Treatment Outcomes of Mesonephric Tumours of the Uterine Cervix: A Systematic Review and Proposal of Embryologically-Oriented Surgical Resection

Background/Objectives: Cervical mesonephric adenocarcinomas (MNACs) are among the rarest neoplasms of the female genital tract. Unlike the majority of cervical cancers, which are predominantly squamous in origin and strongly associated with HPV seropositivity, MNACs are distinct in both histology and pathophysiology. Despite their unique characteristics, MNACs have historically been managed in parallel with squamous cell carcinomas, resulting in a lack of optimised, evidence-based treatment protocols. In this systematic review, we aim to evaluate the current management strategies for MNACs and their associated clinical outcomes. Additionally, we critically appraise existing surgical and adjuvant therapies and propose embryologically oriented surgical techniques to achieve optimal tumour resection. Methods: We performed a systematic search across the MEDLINE, CENTRAL, EMBASE, and ClinicalTrials.gov databases from 1960 to June 2024. The search strategy employed a combination of keywords and MeSH terms, including "Uterine Cervical Neoplasms" [MeSH], "mesonephric tumour", "mesonephric neoplasm", and "mesonephric cancer". All relevant publications, including case reports and case series, were considered. Results: A total of 49 publications were finally included in the analysis, involving a thorough description of 91 MNAC cases. Most patients had stage I disease (70.8%) (n = 51). Hysterectomy was performed in 77 patients. The median follow-up was 29 months (range 1-199 months). Disease recurrence was observed in 35.2% (n = 25) of the cases, with the median disease-free survival (DFS) being 24 months (range 1-199). At the follow-up, 64.8% (n = 46) of patients remained in remission irrespective of the treatment modality, while 27.4% (n = 20) died due to disease progression. Conclusions: Mesonephric neoplasms of the uterine cervix are rare and clinically aggressive cancers that signify poor prognosis. Accurate identification and effective management can be challenging due to their particular anatomic and immunohistochemical characteristics. Therefore, a more tailored embryological-based approach should be considered for an optimal oncologic outcome.

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

AIMS

Mesonephric-like adenocarcinoma (MLA) of the endometrium is often a diagnostic challenge, due to its morphological resemblance to other more common Müllerian neoplasms. This study aimed to retrospectively identify overlooked MLA in a large endometrial carcinoma cohort, using a combination of immunohistochemistry (IHC), morphology and KRAS sequencing.

METHODS AND RESULTS

IHC was conducted on 1094 endometrial carcinomas, identifying 16 potential MLA cases based on GATA3+ and/or TTF1+ and ER- staining patterns, which subsequently underwent detailed histological review, KRAS sequencing and ProMisE molecular classification. Of the IHC screen-positive cases, one was positive for both GATA3 and TTF1, nine were positive for GATA3 only and six were positive for TTF1 only. All IHC screen-positive cases were POLE wild-type. All five tumours in the NSMP category showed morphological features of MLA, while the three MMRd and eight p53abn tumours did not show MLA morphology. The five cases diagnosed as MLA on review were all originally diagnosed as low-grade endometrioid adenocarcinoma probably because of rare morphological patterns, being predominantly papillary or ductal. Four of the five cases harboured a KRAS mutation.

CONCLUSION

This study highlights the importance of a comprehensive diagnostic approach for accurately identifying endometrial MLA and for pathologists to be aware of papillary and ductal patterns in endometrial carcinoma assessment. Further exploration into the molecular landscape of MLA is essential for refining diagnostic criteria and developing targeted therapies.

Case report: The first known case of male retroperitoneal mesonephric-like adenocarcinoma

Aim

We aimed to analyze the clinico-pathological and molecular features of mesonephric-like adenocarcinoma (MLA) to enhance understanding of this tumor type.

Methods

This is the first case of MLA occurring in the retroperitoneum of a male patient. Clinico-pathological and molecular characteristics were analyzed, and the relevant literature was reviewed.

Results

A 65-year-old elderly male was admitted to the hospital with mild bilateral dull pain in the lumbar region for more than 1 month, accompanied by a feeling of dysuria. CT tomography revealed a retroperitoneal tumor. While tumor immuno-histochemistry was positive for CK, CK7, Vimentin, PAX-8, CD10, GATA-3, EMA, and CR to varying degrees, it was negative for P53, WT-1, HMB45, MelanA, CD117, DOG-1, CD34, S-100, ER, PR, AR, CEA, α-inhibin and TTF-1. Ki67 index was <10% in most areas and was approximately 30% in the hotspot areas in the glandular ductal region. Molecular detection (Next-generation sequencing method, 425-gene panel from NanjingShihe Gene Biotechnology Co., Ltd. for targeted DNA enrichment): No clinically significant variants detected. The final pathological diagnosis was a retroperitoneal malignant tumor consistent with a well-moderately differentiated MLA.

Conclusion

MLA in the retroperitoneum of men has not been reported yet. The diverse morphology and unclear molecular characteristics of this tumor mandate careful diagnosis for good clinical outcomes.

Mesonephric carcinoma of the cervix associated with ovarian serous carcinoma: a case report

Malignant mesonephric tumor of the uterine cervix is an extremely uncommon subtype of cervical adenocarcinoma with rare, documented cases in the literature. In this report, we present a case of 58 yo, with abdominal pain and ascites that was found to have a synchronous presence of a mesonephric adenocarcinoma of the cervix and advanced serous ovarian carcinoma on the surgical specimen. The histological study identified a tumor showing a mix of tubular and ductal growth patterns. Immunohistochemical analyses were positive for cytokeratin, vimentin, calretinin and CD10. However, the tumor cells were negative for estrogen receptor and progesterone receptor. The patient received neoadjuvant chemotherapy with a combination of carboplatin and gemcitabine followed by optimal debulking surgery and was alive after 18 months of follow up. The management of this rare case remains unclear due to the absence of management guidelines.

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

AIMS

Decreased oestrogen receptor (ER) expression is a marker of poor prognosis in endometrial carcinomas (EC) of no specific molecular profile (NSMP), but the optimal cut-off to separate high-risk 'low ER' versus low-risk 'high ER' expression has not been defined. Here we characterised the distribution of ER staining in a cohort of ECs.

METHODS AND RESULTS

Biopsy specimens from 120 cases of NSMP EC were stained for ER and assigned an Allred score. In 66 additional cases ER staining of matched biopsy and hysterectomy were compared. Twelve of 120 tumours had an Allred score of 0-3, including three endometrioid carcinomas (EEA) (one G1, two G3), four clear cell carcinomas (CCC), two mesonephric-like adenocarcinoma (MLA) and one each of: gastric-type adenocarcinoma, carcinosarcoma and endometrial carcinoma NOS. Three had Allred scores of 4-5: two MLA and one high-grade carcinoma with yolk sac differentiation. Five had Allred scores of 6: four EEA (one G1, one G2, two G3) and one mixed clear cell and endometrioid carcinoma. The remaining 100 tumours with Allred scores ≥ 7 were all EEA (66 G1, 28 G2, five G3 and one grade unknown). Comparing the biopsy versus hysterectomy ER staining (n = 66), the results were within a single Allred score point, except two cases with strong diffuse expression in the biopsy (Allred 8) and moderate expression in the hysterectomy (Allred 5).

CONCLUSIONS

Most NSMP ECs (> 80%) show high ER expression (Allred score ≥ 7). All non-endometrioid carcinomas and a few endometrioid carcinomas had lower ER expression (Allred score ≤ 6) or were completely negative.

New clinicopathological concept of endometrial carcinoma with integration of histological features and molecular profiles

The dual-stratified pathway of endometrial carcinomas (ECs) has long been dominant. However, in 2013, The Cancer Genome Atlas (TCGA) defined four EC subgroups with distinctive prognoses. Inspired by TCGA, in 2018, the Proactive Molecular Risk Classifier for Endometrial Cancer (ProMisE) provided four pragmatic molecular classifiers to apply surrogate immunohistochemical markers to TCGA subgroup categorization. These trends prompted the revision of 2020 WHO Classification of Female Genital Tumors, 5th edition (2020 WHO classification), in which four molecular subtypes are recognized: POLE-ultramutated; mismatch repair-deficient; p53-mutant; and no specific molecular profile. In the 2020 WHO classification, the diagnostic algorithm is characterized by prioritizing POLEmut over other molecular abnormalities. Following the 2020 WHO classification, Federation of International Gynecology and Obstetrics (FIGO) proposed a new staging system in 2023. The updated system focuses on diagnostic parameters, such as histological type and grade, lymphovascular space invasion, and molecular alterations. These new histomolecular diagnostic concepts of ECs are being accordingly introduced into the routine pathology practice. For the first time, the 2020 WHO classification includes mesonephric-like adenocarcinoma (MLA) as a novel histological entity, mimicking the conventional mesonephric adenocarcinoma, but is considered of Müllerian ductal origin.

Rarely Observed Histopathological Subtypes of Endometrial Malignant Tumors in a Tertiary Care Center: A Case Series

Introduction Endometrial cancer, one of the most prevalent gynecological malignancies, represents a significant contributor to global mortality and morbidity. The histological subtype of this cancer is pivotal in treatment planning and patient risk stratification. This case series, comprising seven cases, underscores the significance of rare endometrial cancer variants and the importance of ancillary studies, specifically immunohistochemistry, in comprehending and diagnosing the condition. Materials and methods The data of all the rare histological subtypes of malignant endometrial tumors encountered from April 2021 to April 2024 were collected. The data collected included age; risk factor; histological type; tumor, node, metastasis (TNM) stage; the International Federation of Gynecology and Obstetrics (FIGO) grade; P53; and mismatch repair (MMR) status. The histopathology specimens were reviewed using a Labomed microscope (LX500) manufactured in India. Images were taken and added wherever necessary, and the results were studied, analyzed, clinically correlated, and are shown in tables. Results Seven rare histopathological subtypes of malignant endometrial tumors were encountered in this period in this tertiary care center. This included mesonephric like adenocarcinoma, high-grade carcinosarcoma, carcinosarcoma with the serous and chondrosarcomatous components, clear cell carcinoma of endometrium, endometrial stromal sarcoma with smooth muscle differentiation, endometrial stromal sarcoma, and undifferentiated sarcoma with focal myxoid degeneration.  Conclusion Diagnosis of uncommon endometrial carcinomas proves to be challenging due to their various histological subtypes, most often with overlapping features. The cornerstone of effective care lies in collaboration with clinicians, radiologists, and pathologists to identify these lesions as early as possible using a multidisciplinary approach for optimal patient outcome management.

Mixed Mesonephric-like Adenocarcinoma, Clear Cell Carcinoma, and Endometrioid Carcinoma Arising from an Endometriotic Cyst

Mesonephric-like adenocarcinoma is a rare neoplasm of the uterine corpus and ovary. Unlike prototypical mesonephric adenocarcinoma of the uterine cervix, which is considered of Wolffian origin, recent evidence suggests that mesonephric-like adenocarcinoma is a Mullerian tumor associated with endometriosis. We report here on a 48-year-old woman with a mixed carcinoma of the ovary that consisted of mesonephric-like adenocarcinoma, clear cell carcinoma, and endometrioid carcinoma, arising from an endometriotic cyst. The mesonephric-like adenocarcinoma consisted of cuboidal cells with vesicular nuclei presenting with a tubular, ductal, papillary, and solid architecture forming nodules. Each component showed distinct immunophenotypes that were consistent with their morphology. The mesonephric-like adenocarcinoma showed diffuse positive staining for paired box 8 and GATA binding protein 3, and negative staining for estrogen and progesterone receptors. A p53 stain exhibited wild-type immunoreactivity. A complete loss of AT-rich interactive domain-containing protein 1A (ARID1A) expression was suggestive of an ARID1A mutation. Manual macrodissection and Sanger sequencing revealed identical KRAS and PIK3CA mutations in all three components. To the best of our knowledge, this is the first report of mesonephric-like adenocarcinoma combined with a clear cell carcinoma and endometrioid carcinoma, which supports the hypothesis that mesonephric-like adenocarcinoma is an endometriosis-associated neoplasm. The report also highlights a potential pitfall in diagnosing mesonephric-like adenocarcinoma combined with clear cell carcinoma.

Mucinous cystadenoma and benign mesonephric-like proliferation in the ovary - Further evidence for clonal relationship

Mesonephric-like adenocarcinomas rarely occur in the uterus and the ovary. Benign mesonephric-like (ML) proliferations and hyperplasia have been described solely within the ovary. Pathogenetic data are very limited. We report a case with microscopic focus of benign ML-proliferation in association with mucinous cystadenoma in the ovary. The immunophenotype was distinct (mucinous tumor: focal weak nuclear positivity for PAX-8, CK 7, patchy cytoplasmic positivity for p16 and negativity for estrogen receptor, CD 10, TTF-1, p53 wildtype; mesonephric component: diffusely positive for PAX-8, CK 7, luminal CD 10, TTF-1, focal staining for estrogen receptor, patchy cytoplasmic for p16, p53 wildtype). On NGS-analysis there was clonal mutation of KRAS p.G12C. The data provide additional evidence for the concept of transdifferentiation (Müllerian tissue representing Wolffian/mesonephric features on histology and immunostaining) within the pathogenesis of mesonephric proliferation of the female genital tract and demonstrate the clonal relationship between these distinct morphologic components.

Comprehensive Immunohistochemical Analysis of Mesonephric Marker Expression in Low-grade Endometrial Endometrioid Carcinoma

Immunohistochemical markers shown to be useful in identifying/confirming mesonephric/mesonephric-like differentiation (MLD markers) include thyroid transcription factor (TTF1), GATA-binding protein 3 (GATA3), and cluster of differentiation 10 (CD10). Only a few studies have examined the expression levels of MLD markers in endometrial endometrioid carcinomas (EECs). This study aimed to analyze the frequency and pattern of MLD marker expression in low-grade EECs. We performed immunostaining for the detection of TTF1, GATA3, and CD10 expression in 50 low-grade EEC tissue samples and evaluated their staining proportion and intensity. Nine tumors (18.0%) expressed at least one MLD marker in varying proportions and intensities, and 2 of these tumors were positive for 2 MLD markers (TTF1/GATA3 and GATA3/CD10, respectively). Three (6.0%) tumors showed moderate-to-strong nuclear TTF1 immunoreactivity in ≤5% of the tumor cells. Five tumors (10.0%) had at least moderate nuclear GATA3 staining, and three of them displayed a staining proportion of ≥15%. Three tumors (6.0%) were focal (mean proportion, 15%) but strongly positive for CD10. Our findings indicate that a subset of EEC can express one or more MLD markers with varying staining proportions and intensities. Given that a diagnosis of uterine mesonephric-like adenocarcinoma should be established based on a combination of characteristic histologic features, unique immunophenotypes, and confirmed molecular findings, pathologists should not exclude EEC based only on the presence of focal immunoreactivity for MLD markers. Awareness of the atypical expression patterns of MLD markers in EEC helps pathologists avoid misdiagnosing EEC as a uterine mesonephric-like adenocarcinoma.

Special Considerations in Classification and Workup of Endometrial Carcinomas

CONTEXT.—

A variety of uncommon malignant endometrial tumors can be challenging to diagnose because of overlapping morphology with more common entities. In some cases, immunohistochemical stains and/or molecular testing allow for more definitive diagnosis or prognostication.

OBJECTIVE.—

To review classic morphologic features of uncommon endometrial tumors, pathologic features of these tumors and their mimics, and the evidence for use of immunohistochemistry and molecular testing in the diagnosis of these tumors.

DATA SOURCES.—

University of Michigan (Ann Arbor) cases and review of pertinent literature about each entity.

CONCLUSIONS.—

Although each of these uncommon endometrial tumors has morphologic mimics, key histologic features, immunohistochemical stains, and molecular testing allow for accurate classification.

Mesonephric and mesonephric-like adenocarcinomas of gynecologic origin: A single-center experience with molecular characterization, treatment, and oncologic outcomes

OBJECTIVES

Mesonephric (MA) and mesonephric-like (MLA) adenocarcinomas are rare cancers, and data on clinical behavior and response to therapy are limited. We sought to report molecular features, treatment, and outcomes of MA/MLA from a single institution.

METHODS

Patients with MA (cervix) or MLA (uterus, ovary, other) treated at Memorial Sloan Kettering Cancer Center (MSK) from 1/2008-12/2021 underwent pathologic re-review. For patients with initial treatment at MSK, progression-free survival (PFS1) was calculated as time from initial surgery to progression or death; second PFS (PFS2) was calculated as time from start of treatment for recurrence to subsequent progression or death. Overall survival (OS) was calculated for all patients. Images were retrospectively reviewed to determine treatment response. Somatic genetic alterations were assessed by clinical tumor-normal sequencing (MSK-Integrated Mutation Profiling of Actionable Cancer Targets [MSK-IMPACT]).

RESULTS

Of 81 patients with confirmed gynecologic MA/MLA, 36 received initial treatment at MSK. Sites of origin included cervix (n = 9, 11%), uterus (n = 42, 52%), ovary (n = 28, 35%), and other (n = 2, 2%). Of the 36 patients who received initial treatment at MSK, 20 (56%) recurred; median PFS1 was 33 months (95% CI: 17-not evaluable), median PFS2 was 8.3 months (95% CI: 6.9-14), and median OS was 87 months (95% CI: 58.2-not evaluable). Twenty-six of the 36 patients underwent MSK-IMPACT testing, and 25 (96%) harbored MAPK pathway alterations.

CONCLUSION

Most patients diagnosed with early-stage disease ultimately recurred. Somatic MAPK signaling pathway mutations appear to be highly prevalent in MA/MLA, and therapeutics that target this pathway are worthy of further study.

Mesonephric-like adenocarcinoma harbours characteristic copy number variations and a distinct DNA methylation signature closely related to mesonephric adenocarcinoma of the cervix

Mesonephric-like adenocarcinoma (MLA) of the female genital tract is an uncommon histotype that can arise in both the endometrium and the ovary. The exact cell of origin and histogenesis currently remain unknown. Here, we investigated whole genome DNA methylation patterns and copy number variations (CNVs) in a series of MLAs in the context of a large cohort of various gynaecological carcinoma types. CNV analysis of 19 MLAs uncovered gains of chromosomes 1q (18/19, 95%), 10 (15/19, 79%), 12 (14/19, 74%), and 2 (10/19, 53%), as well as loss of chromosome 1p (7/19, 37%). Gains of chromosomes 1q, 10, and 12 were also identified in the majority of mesonephric adenocarcinomas of the uterine cervix (MAs) as well as subsets of endometrioid carcinomas (ECs) and low-grade serous carcinomas of the ovary (LGSCs) but only in a minority of serous carcinomas of the uterine corpus (USCs), clear cell carcinomas (CCCs), and tubo-ovarian high-grade serous carcinomas (HGSCs). While losses of chromosome 1p together with gains of chromosome 1q were also identified in both MA and LGSC, gains of chromosome 2 were almost exclusively identified in MLA and MA. Unsupervised hierarchical clustering and t-SNE analysis of DNA methylation data (Illumina EPIC array) identified a co-clustering for MLAs and MAs, which was distinct from clusters of ECs, USCs, CCCs, LGSCs, and HGSCs. Group-wise comparisons confirmed a close epigenetic relationship between MLA and MA. These findings, in conjunction with the established histological and immunophenotypical overlap, suggest bona fide mesonephric differentiation, and support a more precise terminology of mesonephric-type adenocarcinoma instead of MLA in these tumours. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

P16 expression and presence of lymphoid stroma are correlated with good prognosis in mucoepidermoid carcinoma of the head and neck

BACKGROUND

Mucoepidermoid carcinoma (MEC) is the most common salivary gland malignancy. This study was designed to identify valuable prognosticator in MEC.

METHODS

Histopathologic analysis, immunohistochemistry, and in situ hybridization were performed on 128 carcinomas diagnosed as MEC of the head and neck.

RESULTS

Expression of p16 was found in 96 cases (76%) of MEC. Lymphoid stroma was identified in 63 cases (49%). There was a significant correlation between loss of p16 expression and absence of lymphoid stroma. Expression of p16 was significantly associated with better clinicopathologic features. Lymphoid stroma was significantly associated with lower histologic grade. Overall survival (OS) was significantly longer in cases expressing p16 (P = 0.00096) and lymphoid stroma cases (P = 0.0023). Multivariate analysis revealed loss of p16 expression as negative prognosticators for OS.

CONCLUSION

Our data showed p16 expression and the presence of lymphoid stroma were significantly associated with good clinical outcomes. Testing for these factors could lead to better prognostication and treatment of patients with MEC.

[Mesonephric lesions of female genital tract: An overview from benign tumors to emerging malignancy]

Mesonephric lesions in the female genital tract are uncommon and heterogeneous. Those deriving from the upper tract differ from those developing in the lower tract, based on their morphology and immunohistochemical profile. Carcinomas of mullerian origine may display the morphology, the immunoprofile and even the molecular abnormalities of those deriving from mesonephric remnants and are designated mesonephric-like carcinomas. These are high-grade lesions despite their well-differentiated glandular morphology (wolf in sheep's clothing). New entities, such as STK11 adnexal tumors, have merged recently and should not be confused with adnexal tumors of wolffian origin (FATWO), which have a better prognostic and outcome. In this review, we provide an overview of these lesions and their mimickers, in order to help pathologists in the diagnostic approach of these complex and rare neoplasms.

Mesonephric-like adenocarcinoma of the female genital tract: possible role of KRAS-targeted treatment-detailed molecular analysis of a case series and review of the literature for targetable somatic KRAS-mutations

PURPOSE

Mesonephric-like adenocarcinomas (MLA) of the female genital tract represent a rare and relatively recently described neoplasm exhibiting characteristic morphologic and immunohistochemical findings commonly associated with a KRAS-mutation. Most cases display an aggressive clinical behavior, but knowledge about treatment approaches is limited, especially for targeting KRAS.

METHODS

We report a series of eight cases with a detailed molecular analysis for KRAS. These cases as well as the data of previously published cases with detailed information regarding KRAS-mutational events were reviewed for a potential targeted approach and its prognostic impact.

RESULTS

Both the uterine and ovarian MLA harbor a somatic KRAS-mutation in about 85% of the reported cases, affecting the hotspot codons 12 and 13. 15.7% of the endometrial and 15.6% of ovarian MLA are wild type for KRAS. A p.G12A-alteration was seen in 5.6% (5/89) of the endometrial and in 6.2% (2/32) of the ovarian tumors, for p.G12C in 7.9% and 6.2%, for p.G12D in 32.6% and 34.5% and for p.G12V in 36% and 37.5%, respectively. Very limited data are available regarding the prognostic impact of different mutational sites within the KRAS-gene without significant prognostic impact.

CONCLUSION

Because of a specific p.G12C-KRAS somatic mutation, only the minority of MLA (7.9% with uterine and 6.2% with ovarian primary) are potentially targetable by sotarasib in that rare but aggressive subtype of adenocarcinoma of the female genital tract. Until now, the different location of a somatic KRAS-mutation is of no prognostic impact.

Pulmonary metastasis of stage I, low-grade endometrioid carcinoma: two case reports and the literature review

Endometrial cancer (EC) is the most common malignant tumor of the female reproductive system, and the majority of ECs are low histological grade and confined to the uterus, resulting in a good prognosis. However, metastasis to the lung from a low-grade and early-stage endometrial endometrioid carcinoma (EEC) is extremely rare. Therefore, it is crucial to accurately differentiate between primary pulmonary malignancy and extra-thoracic malignancy presenting as metastatic disease, and flexible bronchoscopy with tissue acquisition plays a key role in this process. Despite its importance, there is limited literature available on the cytology of metastatic endometrial carcinoma in liquid-based cytology of bronchial brush (BB). In this article, we present two rare cases of lung metastasis from low-grade and early-stage EEC, along with a detailed analysis of the cytologic features observed in BB samples. These cases highlight the significance of cytological and histological pathology, complemented by immunohistochemistry (ICH) analysis, in the diagnosis and management of EEC patients. Pathologists should pay close attention to these aspects, while gynecologists need to be mindful of the follow-up and management of early-stage, low-grade EEC patients. By focusing on these areas, healthcare professionals can effectively contribute to the improved care and outcomes of patients with EEC.

The Updated World Health Organization Classification Better Predicts Survival in Patients With Endocervical Adenocarcinoma (KROG 20-07)

PURPOSE

The 2020 World Health Organization classification divided endocervical adenocarcinoma (ADC) into human papillomavirus-associated (HPVA) and human papillomavirus-independent (HPVI) ADCs. This multi-institutional study aimed to investigate the clinical features and prognosis of patients with endocervical ADC based on the updated World Health Organization classification.

METHODS AND MATERIALS

We retrospectively reviewed the 365 patients with endocervical ADC who underwent radical hysterectomy from 7 institutions. Tumor characteristics, patterns of failure, and survival outcomes were compared between HPVA and HPVI ADCs.

RESULTS

Two hundred seventy-five (75.3%) and 90 (24.7%) patients had HPVA and HPVI ADC diagnoses, respectively. In all cases, the 5-year disease-free survival (DFS) and overall survival (OS) rates were 58.2% and 71.3%, respectively. HPVI ADC showed higher rates of local recurrence (25.6% vs 10.9%) and distant metastasis (33.3% vs 17.5%) than HPVA ADC. Multivariate survival analysis revealed that HPVI ADC showed significantly worse DFS (hazard ratio [HR], 1.919; 95% confidence interval [CI], 1.324-2.781; P < .001), distant metastasis-free survival (HR, 2.100; 95% CI, 1.397-3.156; P < .001), and OS (HR, 2.481; 95% CI, 1.586-3.881; P < .001) than HPVA ADC. Patients with gastric- and serous-type HPVI ADC had significantly worse OS than those with other HPVI ADCs (P = .020). Similarly, invasive stratified mucin-producing-type HPVA ADC showed significantly worse OS than other HPVA ADCs (P < .001).

CONCLUSIONS

We demonstrated that HPVI ADC exhibited inferior DFS and OS and higher rates of local and distant recurrence compared with HPVA ADC. Gastric- and serous-type HPVI ADCs and invasive stratified mucin-producing-type HPVA ADC showed worse OS than other types of HPVI and HPVA ADCs, respectively. Our observation of significant differences in prognoses according to the histologic types needs to be validated in larger cohorts of patients with endocervical ADC.

Mesonephric-like Adenocarcinoma of the Uterine Corpus: Genomic and Immunohistochemical Profiling with Comprehensive Clinicopathological Analysis of 17 Consecutive Cases from a Single Institution

Data on genetic and immunophenotypical characteristics of uterine mesonephric-like adenocarcinoma (MLA) remain limited. Therefore, we aimed to investigate the clinicopathological, immunohistochemical, and molecular features of uterine MLA. We performed targeted sequencing, array comparative genomic hybridization, and immunostaining in 17, 13, and 17 uterine MLA cases, respectively. Nine patients developed lung metastases. Eleven patients experienced disease recurrences. The most frequently mutated gene was Kirsten rat sarcoma viral oncogene homolog (KRAS; 13/17). Both the primary and matched metastatic tumors harbored identical KRAS (3/4) and phosphatase and tensin homolog deleted on chromosome 10 (1/4) mutations, and did not harbor any additional mutations. A total of 2 of the 17 cases harbored tumor protein 53 (TP53) frameshift insertion and deletion, respectively. Chromosomal gains were detected in 1q (13/13), 10 (13/13), 20 (10/13), 2 (9/13), and 12 (6/13). Programmed cell death-ligand 1 overexpression or mismatch repair deficiency was not observed in any of the cases. Initial serosal extension and lung metastasis independently predicted recurrence-free survival with hazard ratios of 6.30 and 7.31, respectively. Our observations consolidated the clinicopathological and molecular characteristics of uterine MLA. Both clinicians and pathologists should consider these features to make an accurate diagnosis of uterine MLA and to ensure appropriate therapeutic management of this rare entity.

Radiologic Findings of Mesonephric-Like Adenocarcinoma of the Uterine Corpus: A Case Report

According to the 2020 World Health Organization classification, mesonephric-like adenocarcinoma (MLA) is newly categorized as a subtype of endometrial carcinoma and remains a relatively unknown disease owing to its rarity. To the best of our knowledge, radiological findings of MLA have not been reported in the English literature. The uterine MLAs show a worse clinical prognosis and a more aggressive biological behavior than the usual endometrial carcinoma. Herein, we present the imaging findings of a 65-year-old female with a MLA in the uterine corpus. The tumor was a solid endometrial mass with deep myometrial invasion, poor contrast enhancement, and moderate diffusion restriction.

Ovarian Combined Serous Borderline Tumor/Low-grade Serous Carcinoma and Mesonephric-like Lesion: Report of 2 Cases With New Observations

Ovarian combined serous borderline tumor/low-grade serous carcinomas (SBT/LGSC) and mesonephric-like adenocarcinomas (MLA) have been previously reported and the presence of identical oncogenic somatic mutations in both components supports the concept that at least some of MLAs arise from a Müllerian origin. We report 2 cases of ovarian combined SBT/LGSC and mesonephric-like lesion. Case 1 was a 70-yr-old woman presented with a liver lesion and omental carcinomatosis. Histologic examination revealed biphasic tumors in bilateral ovaries consisting of conventional SBT and invasive MLA with extraovarian spread. The right ovary also had a component of cribriform variant of SBT/noninvasive LGSC. The SBT/LGSC component was diffusely positive for Pax8, WT-1, and ER, focally positive for PR, and negative for GATA3, while the MLA component was diffusely positive for GATA3 but negative for WT-1, ER, and PR. Molecular analysis revealed a KRAS G12V mutation in both the SBT/LGSC and MLA components, indicating their clonal origin. Case 2 was a 58-yr-old woman who presented with conventional type SBT in both ovaries. In addition, the left ovarian tumor demonstrated a few areas (each <5 mm) of mesonephric-like differentiation/hyperplasia in close proximity to the serous-type epithelium, with an immunophenotype of focal GATA3 expression, luminal pattern of CD10 staining and negative WT-1, ER, and PR staining. This phenomenon has been reported in endometrioid borderline tumor but not in any serous type lesions. The findings in case 1 provide further evidence to demonstrate the clonal relationship between these morphologically and immunophenotypically distinct components. It also supports the theory that, unlike cervical mesonephric carcinomas originating from mesonephric remnants, MLAs are derived from a Müllerian-type lesion with differentiation into mesonephric lineage. The presence of a hyperplastic mesonephric-like lesion/differentiation in case 2 indicates that a precursor lesion in the same lineage with the potential to develop into MLA exists in the ovary.

Synchronous ovarian and uterine mesonephric-like carcinoma that potentially arose from endometrioid adenofibroma: A case report

Mesonephric-like carcinoma histologically resembles mesonephric adenocarcinoma (MA) of the cervix. MA arises from mesonephric duct remnants. However, the origin of mesonephric-like carcinoma is not extensively studied because of its rarity. Here, we present a case of synchronous ovarian and uterine mesonephric-like carcinoma that potentially arose from endometrioid adenofibroma. A 69-year-old woman presented with an abdominal mass with no genital bleeding. She underwent simple total abdominal hysterectomy and bilateral adnexal resection. Histological and immunohistochemical analyses were consistent with mesonephric-like carcinoma involving both ovaries and the uterus. Endometrioid adenofibroma was present in both ovaries, while adenomyosis was observed in the uterus. The glandular duct of the endometrioid adenofibroma in the right ovary had areas suggestive of precursor lesions of mesonephric-like carcinoma. All tumors exhibited the KRAS G12D mutation. These findings suggest that the origin of the mesonephric-like carcinoma was the Müllerian duct, and that the ovarian and uterine tumors were monoclonal.

Estrogen/Progesterone Receptor Loss, CTNNB1 and KRAS Mutations Are Associated With Local Recurrence or Distant Metastasis in Low-Grade Endometrial Endometrioid Carcinoma

A subset of endometrial endometrioid carcinomas (EECs) with low-grade histology recur with poor outcomes. Published evidence suggests that poor outcomes may be associated with loss of expression of ER-alpha (ER-α) as well as with β-Catenin-1 ( CTNNB1 ) and Kirsten rat sarcoma viral oncogene homolog ( KRAS ) mutations. This study reports on institutional experience with the incidence of recurrence in low-grade EEC and their association with CTNNB1 and KRAS mutations as well as estrogen/progesterone receptor (ER/PR) expression. Forty-eight (8.5%) out of 568 cases of low-grade EEC with biopsy-proven recurrence were identified; and were analyzed by immunohistochemistry for ER, PR, p53, MMR protein, and mutation analysis for exon 3 of the CTNNB1 and exon 2 of KRAS in relation to recurrence type, local or distant metastasis/recurrence. Twenty-three patients (4%) developed local, and 25 patients (4.4%) developed distant metastases/recurrence. Decreased expression or loss of ER/PR was found in 17/44 (38.6%) patients with recurrence. Eighty-four percent of patients with low-grade EEC and local recurrence had CTNNB1 mutations. Seventy-three percent of patients with distant metastasis/recurrence had KRAS mutations. The association of these mutations with the type of recurrence was statistically significant for both. Five cases with the morphology of low-grade EEC were reclassified as mesonephric-like carcinoma and were universally characterized by distant metastasis/recurrence, loss of ER/PR expression, large tumor size, absence of CTNNB1 mutations, and the presence of KRAS mutations. In low-grade EEC, CTNNB1 and KRAS mutations are associated with local recurrence and distant metastasis/recurrence, respectively, suggesting that these 2 different progression types may be conditioned by tumor genotype. ER/PR immunohistochemistry may be helpful in identifying poor performers in low-grade EEC. Furthermore, identification of the decreased expression or loss of ER/PR in tumors with low-grade histology should prompt consideration of mesonephric-like carcinoma, which is a more aggressive tumor than the low-grade EEC. KRAS mutations were associated with distant metastasis/recurrence in tumors with and without mesonephric-like phenotype.

Cytological features of mesonephric-like adenocarcinoma of the uterine corpus

BACKGROUND

Although several studies have documented the histological features of uterine mesonephric-like adenocarcinoma (MLA), its cytological features have been rarely reported.

METHODS

We searched for histologically confirmed uterine MLA cases in the pathology archives of three institutions between 2010 and 2021. All available cytology slides were examined to identify the cytological features of uterine MLA.

RESULTS

We included 16 patients with uterine MLA and reviewed the slides obtained from 21 cytology samples. Samples were obtained from the cervicovagina (9/21, 42.9%), peritoneal washing (8/21, 38.1%), pleural effusion (2/21, 9.5%), and transbronchial needle aspiration of mediastinal lymph node (2/21, 9.5%). Preparation methods included ThinPrep (11/21, 52.4%), SurePath (8/21, 38.1%), and conventional smear (2/21, 9.5%). Regardless of the sampling site and preparation method, cytology samples displayed tight three-dimensional cellular clusters showing monotonous, small-to-medium-sized, round, hyperchromatic nuclei, indistinct nucleoli, scant cytoplasm, and high nuclear-to-cytoplasmic ratio. Approximately half of the samples (10/21, 47.6%) showed hyaline-like globules. Mitotic figures (7/21, 33.3%) and apoptotic bodies (13/21, 61.9%) were also observed. No tumor diathesis or nuclear feathering was identified.

CONCLUSIONS

Irrespective of sampling site and preparation method, the majority of uterine MLA cases showed the following cytological features: tight three-dimensional cellular clusters showing small-to-medium-sized, round, hyperchromatic nuclei with indistinct nucleoli and high nuclear-to-cytoplasm ratio. In case a cytology sample suspicious of a glandular lesion displays these cytological features, which are distinct from those of endocervical adenocarcinoma, uterine MLA should be included in the differential diagnosis.

Mesonephric Adenocarcinoma and Mesonephric-like Adenocarcinoma of the Urinary Tract

Given the association of mesonephric adenocarcinoma (MA) of the uterine cervix with florid mesonephric hyperplasia, one would expect MAs to rarely arise in other anatomical locations that harbor mesonephric remnants. In contrast, mesonephric-like adenocarcinoma (MLA) is thought to arise from Müllerian origin without an association with mesonephric remnants. The current case series characterizes 4 cases of MA arising in the urinary bladder (1 woman and 3 men), 1 case of MA in the perirenal region (woman), and 1 case of MLA in the ureter (woman). All cases displayed morphologic features similar to MA of the uterine cervix and MLA of the ovary and endometrium, characterized by predominant tubular and focal glandular/ductal architecture. Mesonephric remnants in the bladder wall were closely associated with adjacent MA in cases 1 and 4. MLA in case 6 was associated with mesonephric-like proliferations and endometriosis. All cases (6/6) were diffusely positive for Pax8, and all displayed a luminal pattern of CD10 staining, except case 4 for which CD10 immunostain was not available for review. Gata3 was either focally positive (cases 1, 2, and 6), negative (case 3), or diffusely positive (case 5). TTF-1 was diffusely expressed in cases 1 and 3 and negative in cases 2, 5, and 6. Although a KRAS G12C somatic mutation was detected in case 6, hotspot mutations in KRAS, NRAS, and PIK3CA were not present in other tested cases. Our study demonstrates that MAs and MLAs of the urinary tract share similar histopathogenesis, morphology, and immunophenotype to their counterparts in the female genital tract. We propose that, in the urinary tract, MA might be classified as a distinctive tumor that arises from mesonephric remnants or presumed Wolffian origin if they are not related to Müllerian-type precursors. The tumor displaying similar morphology and immunoprofile to MA but associated with Müllerian-type precursors should be classified as MLA.

Microscopic Sertoliform Sex Cord Proliferations: A Rare Incidental Finding Associated With Endometriosis and Ovarian Epithelial Neoplasia

Microscopic sex cord proliferations are a rare incidental finding seen in association with ovarian and uterine stromal or epithelial neoplasms and more uncommonly non-neoplastic conditions such as endometriosis and adenomyosis. They may also occur in the absence of other pathology, as an incidental finding in the ovaries of pregnant women and in heterotopic locations such as the fallopian tube. Most reports of this phenomenon describe adult granulosa cell tumor-like morphology. Herein, we describe 4 cases of microscopic sex cord proliferations with Sertoliform features, occurring in the stromal component of endometriosis or in the wall of an epithelial ovarian neoplasm; 2 of the patients with endometriosis had concurrent endometrioid adenocarcinoma (1 uterine corpus, 1 ovary). The proliferations were positive with sex cord markers inhibin and calretinin. As far as we are aware, such Sertoliform proliferations have not been reported previously in endometriosis and have only rarely been described in association with ovarian epithelial neoplasia. It is likely that such proliferations represent a benign non-neoplastic phenomenon. Awareness of this phenomenon is important in order to avoid misdiagnosis as a sex cord or other neoplasm. In reporting this unusual phenomenon, we review incidental sex cord and sex cord-like proliferations in the female genital tract.

Mesonephric-like Carcinosarcoma of the Uterine Corpus: Clinicopathological, Molecular and Prognostic Characteristics in Comparison With Uterine Mesonephric-like Adenocarcinoma and Conventional Endometrial Carcinosarcoma

BACKGROUND/AIM

This study aimed to investigate the clinicopathological, prognostic and molecular characteristics of uterine mesonephric-like carcinosarcoma (MLCS).

PATIENTS AND METHODS

We collected clinical, pathological, and genetic information from 12 MLCS patients, and analyzed their differences from mesonephric-like adenocarcinoma (MLA) and conventional endometrial carcinosarcoma (CECS).

RESULTS

The epithelial component was exclusively MLA in all MLCS cases. Metastatic and recurrent tumors consisted predominantly or exclusively of MLA in the majority of MLCS cases. Patients with MLCS and MLA presented with more advanced-stage disease than those with CECS. They also exhibited post-treatment recurrence and lung metastases more frequently than CECS. Disease-free survival rates of MLCS and MLA were shorter than those of CECS. Tumor protein 53 gene mutations were detected in four MLCS cases.

CONCLUSION

The predominance or exclusive presence of MLA in metastatic and recurrent tumors highlights the possibility that MLA may determine the clinical outcomes of patients with MLCS. Further studies are required to provide direct molecular evidence of the monoclonal origin of uterine MLCS.

Genomic landscape of endometrial carcinomas of no specific molecular profile

Endometrial carcinomas (ECs) classified by The Cancer Genome Atlas (TCGA) as copy number-low (also referred to as "no specific molecular profile" [NSMP]) have a prognosis intermediate between POLE-mutated and copy number-high ECs. NSMP-ECs are a heterogeneous group, however, comprising both relatively indolent and aggressive ECs. We identified a total of 472 NSMP-ECs among 1,239 ECs that underwent clinical sequencing of 410-468 cancer-related genes. Somatic mutation and copy number alteration data were subjected to unsupervised hierarchical clustering, which identified three genomic clusters. Random sampling with stratification was used to choose ~80 endometrioid ECs from each cluster, resulting in a study size of 240 endometrioid ECs as well as an additional 44 non-endometrioid NSMP-ECs. Cluster 1 (C1, n = 80) consisted primarily of NSMP-ECs with PTEN and PIK3R1 mutations, Cluster 2 (C2, n = 81) of tumors with PTEN and PIK3CA mutations and Cluster 3 (C3, n = 79) of NSMP-ECs with chromosome 1q high-level gain and lack of PTEN mutations. The majority (72.7%) of non-endometrioid NSMP-ECs mapped to C3. NSMP-ECs from C3 were more likely to be FIGO grade 3 (30%), estrogen receptor-negative/weak (54.5%) and FIGO stages III or IV. In multivariate analysis, molecular clusters were associated with worse overall survival outcomes with C3 tumors having the worst (hazard ratio: 4) and C1 tumors having the best outcome. In conclusion, NSMP-ECs are a heterogenous group of tumors and comprise both aggressive and clinically low-risk ECs that can be identified based on mutation and copy number data.

Mucinous Tumor Coexisting With Mesonephric-like Proliferation/Tumor in the Ovary: A Novel Association

The literature indicates that mesonephric carcinoma (MC) and mesonephric-like adenocarcinoma (MLA) typically lack mucinous and squamous features/differentiation. We report 4 cases of ovarian mucinous tumors (1 mucinous cystadenofibroma and 3 mucinous borderline tumors/atypical proliferative mucinous tumors [MBT/APMT]) co-existing with mesonephric-like lesions which were highlighted by Gata3 and Pax8 expression. All cases contained benign mesonephric-like proliferations (MLP) which focally displayed gastrointestinal-type mucinous metaplasia/differentiation and some were intimately admixed with mucinous glands associated with the mucinous tumor. Metaplastic mucinous epithelium retained expression of Gata3 and Pax8 in some areas while 1 mucinous cystadenofibroma and 1 MBT/APMT were focally positive for Pax8. Along with these mesonephric components, case 1 exhibited features of mesonephric hyperplasia and in 2 cases, 3 and 4, MLA was identified. In case 4, a KRAS c.35G>T (p.Gly12Val) somatic mutation was detected in both the MBT/APMT and the MLA, indicating a clonal origin. This same mutation was also detected in the benign MLP, indicating that it was likely an early genetic event. A CTNNB1 c.98C>T (p.Ser33Phe) somatic mutation, FGFR2 amplification, and CDKN2A/p16 deletion were only detected in the MLA but not in the MBT/APMT. Our result provides evidence to demonstrate the clonal relationship between these morphologically distinct components. Although speculative, we postulate that benign MLPs may give rise to lineage-specific mucinous and mesonephric-like lesions and propose that the MLPs are a new possible origin of some ovarian mucinous tumors. Whether these MLPs arise through transdifferentiation of Müllerian tissue or represent true mesonephric remnants, however, remains largely unknown.

Mesonephric-Like Adenocarcinoma of Uterine Corpus: A Clinicopathological and Targeted Genomic Profiling Study in a Single Institution

Background

Mesonephric-like adenocarcinoma (MLA) is a recently characterized, rare, and aggressive neoplasm that mostly arises in the uterine corpus and ovary. MLA shows characteristic pathological features similar to mesonephric adenocarcinoma of the cervix. The origin of MLA is still controversial and recognition of it remains challenging for pathologists. The aim of this study was to enrich the clinicopathological features of MLA in the uterine corpus and explore its molecular alterations by targeted next-generation sequencing (NGS).

Methods

Four cases of MLA were identified among a total of 398 endometrial carcinomas diagnosed in our institution between January 2014 and December 2021. Immunohistochemistry and targeted NGS spanning 437 cancer-relevant genes were performed.

Results

The most common symptom was abnormal vaginal bleeding, and the average age was 68 years. Histologically, the tumors showed a mixture of varied growth patterns including papillary, glandular, tubular, cribriform, solid, and slit-like architectures, which were lined by columnar to cuboidal cells with overlapping vesicular nuclei and sometimes nuclear grooves. Intraluminal eosinophilic colloid-like secretions were focally evident in three of the four cases. Immunohistochemically, the MLAs were positive for GATA3 (4/4), TTF-1 (3/3), luminal CD10 (3/3), calretinin (2/3), and patchy P16 (3/3) and were negative for ER (0/4) and PR (0/4). The expression of P53 was “wild type” (4/4). By targeted NGS, 3/4 (75%), 2/4 (50%), and 1/4 (25%) cases harbored PIK3CA, KRAS, and PTEN mutations, respectively. None of the tumors had mutations in DNA mismatch repair genes, ARID1A/B, POLE, CTNNB1, SMARCA4, or TP53. At the time of diagnosis, three were presented with FIGO IB stage and one with IIIC stage. Two patients received postoperative chemotherapy and radiotherapy and they were alive without evidence of disease at 8 and 56 months follow-up, respectively. One patient developed pulmonary metastasis 13 months after surgery and chemotherapy, and one was dead of the disease 24 months after the operation without adjuvant therapy.

Conclusions

MLA is a rare and aggressive malignancy, representing approximately 1% of all endometrial carcinomas. It exhibits mixed architectures associated with distinctive immunophenotype and recurrent KRAS and PIK3CA mutations, supporting classified as of Müllerian origin with mesonephric differentiation.

An unusual case of carcinoma with mesonephric-like features with a spindle cell component diagnosed on the Pap test of the uterine cervix: Cytomorphologic and immunophenotypic features and diagnostic pitfalls

Mesonephric-like adenocarcinomas (MLA) are rare neoplasms arising in the cervix, endometrium, and ovary. In contrast to mesonephric carcinomas (MC), mesonephric-like adenocarcinomas are not associated with mesonephric remnants. Both entities have a similar appearance with regards to varying histomorphology patterns, including glandular, tubular, spindled, solid, and papillary, and have a specific immunophenotype and molecular features. We present a case of a 54-year-old HPV-negative woman with a Pap test that exhibits high-grade malignancy. The cell block displayed malignant cells with positive stains for PAX8, GATA3, and TTF1 by immunohistochemistry. The diagnosis of adenocarcinoma with mesonephric like features was rendered. MLA can be challenging on the small specimens and often misinterpreted as other endometrial neoplasms. Furthermore, the accurate diagnosis carries a well-described risk of aggressive clinical behavior.

Mesonephric-like Adenocarcinoma of the Female Genital Tract: From Morphologic Observations to a Well-characterized Carcinoma With Aggressive Clinical Behavior

Mesonephric-like adenocarcinoma (MLA) was introduced as a new tumor type in the endometrium and the ovary in the 2020 World Health Organization (WHO) Classification. This is a rare recently described (2016) and clinically aggressive carcinoma with a propensity for distant spread, especially to the lungs. MLA has a characteristic morphology and immunophenotype (hormone receptor negative; TTF1 and/or GATA3 positive). These neoplasms are commonly associated with KRAS and PIK3CA mutations and in the Cancer Genome Atlas (TCGA) molecular classification of endometrial carcinomas fall into the copy number low/no specific molecular profile category. Although they show significant morphological, immunophenotypic and molecular overlap with cervical mesonephric adenocarcinomas, there are other parameters which suggest a Mullerian origin and, as such, the term MLA seems apt. MLA can be added to the list of endometriosis-associated ovarian neoplasms. In this paper, I outline the series of events which lead to the first description of MLA and review the subsequent literature on this tumor type which has expanded on the morphologic features and immunophenotype, discovered the molecular underpinnings and elucidated the clinical behavior. The discovery of MLA represents an example of "new" entities still to this day being discovered through careful morphologic observations and referral of cases for specialist opinion.

Uncommon and Difficult High-Grade Endometrial Carcinomas

This article presents features of uncommon high-grade endometrial carcinomas that often pose a significant diagnostic challenge. An update on undifferentiated and dedifferentiated endometrial carcinoma is first provided, followed by discussions on more recently defined entities such as mesonephric-like carcinoma of the endometrium and gastric-type endometrial carcinomas. Finally, endometrial carcinoma with germ cell or trophoblastic-like components is discussed.

Alveolar Soft Part Sarcoma of the Uterus: Clinicopathological and Molecular Characteristics

Alveolar soft part sarcoma (ASPS) is a rare malignant mesenchymal tumor mainly affecting adolescents and young adults, with a predilection for the deep soft tissues of extremities. ASPS arising in the female genital tract is extremely rare and poses a significant diagnostic challenge. We herein present two rare cases of ASPS, one occurring in the uterine corpus of a 27-year-old woman, and the other in the uterine cervix of a 10-year-old girl. We described the clinical, histological, immunophenotypical, and molecular characteristics of primary uterine ASPS. We performed immunostaining for transcription factor E3 (TFE3), human melanoma black 45 (HMB45), melan-A, desmin, pan-cytokeratin (CK), paired box 8 (PAX8), CD10, hormone receptors, and S100, and targeted RNA and DNA sequencing using commercially available cancer gene panel. In case 1, a 27-year-old woman was referred to our hospital after laparoscopic uterine myomectomy at an outside hospital. Imaging studies revealed a residual tumor in the uterine corpus. In case 2, a 10-year-old girl underwent surgical excision for the cervical mass and was diagnosed as having ASPS. She was then referred to our hospital for further management. Both patients received total hysterectomy. Histologically, they displayed characteristic histological features of ASPS. Strong nuclear TFE3 immunoreactivity, periodic acid-Schiff-positive, diastase-resistant intracytoplasmic rod-shaped crystalloids or granules, and the identification of ASPSCR1–TFE3 fusion confirmed the diagnosis of ASPS in both cases. Lack of immunoreactivity for HMB45, melan-A, desmin, pan-CK, PAX8, and S100 excluded the possibility of perivascular epithelioid cell tumor, clear cell sarcoma, metastatic renal cell carcinoma, granular cell tumor, and paraganglioma. Our observations can help pathologists make an accurate diagnosis of uterine ASPS and suggest that pathologists should include primary uterine ASPS in the differential diagnosis of uterine mesenchymal tumors.

Mesonephric-like Adenocarcinoma of the Ovary: Clinicopathological and Molecular Characteristics

Mesonephric-like adenocarcinoma (MLA) arising in the ovary is a rare malignant tumor of the female genital tract. Although the clinicopathological and molecular characteristics of uterine MLA have been accumulated, those of ovarian MLA have not been firmly clarified. In this study, we investigated the clinicopathological, immunohistochemical, and genetic features of five ovarian MLAs. A review of electronic medical records and pathology slides, immunostaining, and targeted sequencing was performed. On imaging, ovarian MLA presented as either a mixed solid and cystic mass or a purely solid mass. One, three, and one patient were diagnosed as having FIGO stage IA, IC, and II MLA, respectively. Four patients with stage IC–II tumor underwent post-operative adjuvant chemotherapy. Three of the four patients whose follow-up information was available did not experience recurrence. In contrast, the remaining patient with stage IA tumor who did not receive any adjuvant treatment developed multiple metastatic recurrences at post-operative 13 months. Histologically, ovarian MLAs characteristically displayed architectural diversity, compactly aggregated small tubules, and eosinophilic intraluminal secretions. Four tumors were found to be associated with endometriotic cysts. Two cases showed some areas of high-grade nuclear atypia, brisk mitotic activity, and necrosis. Immunohistochemically, all cases showed positive immunoreactivities for at least three of the four examined mesonephric markers (GATA3, PAX2, TTF1, and CD10), lack of WT1 expression, non-diffuse p16 immunoreactivity, and wild-type p53 immunostaining pattern. Targeted sequencing analysis revealed that all four examined cases harbored pathogenic KRAS mutations: p.G12V (2/4); p.G12D (1/4); and p.G12C (1/4). In addition, we reviewed the previous literature reporting 60 cases of ovarian MLA. Our findings corroborate those of the previous data regarding the clinical presentation, histological features, immunophenotypes, and molecular alterations. Our observations should encourage pathologists to recognize and accurately diagnose this rare but distinct entity.

Mesonephric-like Adenocarcinoma of the Uterine Corpus: Comprehensive Immunohistochemical Analyses Using Markers for Mesonephric, Endometrioid and Serous Tumors

Mesonephric-like adenocarcinoma (MLA) of the uterine corpus is a rare but distinct malignant tumor of the female genital tract, demonstrating a characteristic morphology and unique immunohistochemical profiles and molecular alterations. We conducted immunohistochemical staining (IHC) to make precise differential diagnoses of uterine MLAs from common histological subtypes of endometrial carcinomas. We collected 25 uterine MLAs and performed IHC for GATA3, TTF1, CD10, ER, PR, p16, p53, and HER2. Seventeen cases (68.0%) showed at least moderate nuclear GATA3 immunoreactivity in ≥25% of tumor cells. Most cases expressed TTF1 (17/21, 81.0%) and CD10 (luminal; 17/21, 81.0%). Heterogeneous TTF1 expression was noted in 12 cases. An inverse pattern of GATA3 and TTF1 staining was observed in eight cases (32.0%). Three cases (12.0%) showed moderate-to-strong ER expression in ≥25% of tumor cells, and two cases (8.0%) showed moderate-to-strong PR expression in ≥5% of tumor cells. These hormone receptor-positive MLAs varied in intensity and proportion of GATA3 staining. None of the 25 cases exhibited either diffuse and strong p16 expression or aberrant p53 expression. Five cases (20.0%) showed equivocal HER2 immunoreactivity (score 2+), but HER2 FISH confirmed that none of them exhibited HER2 gene amplification. In summary, a small subset of uterine MLAs displayed atypical IHC results: focal but strong expression of ER or PR, the complete absence of GATA3 immunoreactivity, the concurrent expression of mesonephric and hormone receptors, and the inverse pattern of GATA3 and TTF1 staining. These unusual immunophenotypes may complicate the differential diagnosis of MLA. Moreover, pathologists should be encouraged to interpret the IHC results cautiously.

A Timely Update of Immunohistochemistry and Molecular Classification in the Diagnosis and Risk Assessment of Endometrial Carcinomas

CONTEXT.—

Endometrial carcinoma is the most common gynecologic malignancy in the United States and has been traditionally classified based on histology. However, the distinction of certain histologic subtypes based on morphology is not uncommonly problematic, and as such, immunohistochemical study is often needed. Advances in comprehensive tumor sequencing have provided novel molecular profiles of endometrial carcinomas. Four distinct molecular subtypes with different prognostic values have been proposed by The Cancer Genome Atlas program: polymerase epsilon ultramutated, microsatellite instability hypermutated, copy number low (microsatellite stable or no specific molecular profile), and copy number high (serouslike, p53 mutant).

OBJECTIVE.—

To discuss the utilities of commonly used immunohistochemical markers for the classification of endometrial carcinomas and to review the recent advancements of The Cancer Genome Atlas molecular reclassification and their potential impact on treatment strategies.

DATA SOURCES.—

Literature review and authors' personal practice experience.

CONCLUSIONS.—

The current practice of classifying endometrial cancers is predominantly based on morphology. The use of ancillary testing, including immunohistochemistry, is helpful in the identification, differential diagnosis, and classification of these cancers. New developments such as molecular subtyping have provided insightful prognostic values for endometrial carcinomas. The proposed The Cancer Genome Atlas classification is poised to gain further prominence in guiding the prognostic evaluation for tailored treatment strategies in the near future.

Invasive Stratified Mucin-producing Carcinoma (ISMC) of the Uterine Cervix: Clinicopathological and Molecular Characteristics With Special Emphasis on the First Description of Consistent Programmed Death-ligand 1 (PD-L1) Over-expression

BACKGROUND/AIM

Invasive stratified mucin-producing carcinoma (ISMC) of the uterine cervix has been reported to be more aggressive than other subtypes of endocervical adenocarcinoma. We investigated the clinicopathological and molecular characteristics of eight ISMCs.

PATIENTS AND METHODS

We reviewed the electronic medical records and pathology slides of eight patients with ISMC and conducted programmed death-ligand 1 (PD-L1) immunostaining and targeted sequencing.

RESULTS

The patients were between 31 and 54 years. Six tumors were pure ISMCs, and two showed co-existing squamous cell carcinoma and usual-type endocervical adenocarcinoma. Lymph node metastases were detected in three cases. Three patients developed distant metastases to the adnexa, lungs, inguinal lymph nodes, and small intestine. Two patients experienced disease progression, and three developed postoperative local recurrences. All tumors showed PD-L1 over-expression, with a mean combined positive score of 73.8 (range=30-100). One tumor harbored erb-b2 receptor tyrosine kinase 2 amplification.

CONCLUSION

ISMC of the uterine cervix exhibits a high risk of recurrence, metastasis, and resistance to chemoradiation therapy. PD-L1 over-expression was consistently observed in all ISMCs. This finding raises the possibility that patients with ISMC may benefit from PD-L1 immunotherapy.

Mesonephric adenocarcinomas in female genital tract: A case series

ABSTRACT

Mesonephric adenocarcinoma (MNAC) is a very rare tumor that originates from mesonephric duct remnants of the female genital tract. Only a few cases were reported in the literature, and most of them occurred in the cervix, extremely rare in the uterine body and ovary. MNAC was rarely reported to arise in the uterine corpus, but never was reported in the ovary. Mesonephric-like adenocarcinomas are recently suggested to describe these neoplasms arising from the uterine corpus and ovary. Due to the rareness of the disease, little is known regarding clinical characteristics, pathological diagnosis, prognosis, and optimal management strategy of MNAC in the female reproductive system. We report a series of MNACs arising from the vagina, cervix, uterine corpus, ovary, and fallopian tube, to summarize the clinical characteristics, pathological diagnosis, treatment, and prognosis.We retrospectively analyzed all MNACs in the female genital tract derived from our institute from January 2010 till January 2020. Patients' clinical details and follow-up were obtained from hospital records and scans were obtained from picture archiving and communication system.A total of 11 patients were included. The median age of onset of symptoms was 52 years. All patients underwent total hysterectomy and bilateral salpingo-oophorectomy, and lymph node dissections were performed in 7/11 (63.6%) patients. Two/eleven (18.2%) received neoadjuvant chemotherapy before surgery and 7/11 (63.6%) received adjuvant chemotherapy after primary surgery. Of the 11 patients, only 1 patient received adjuvant radiation therapy. One patient died at the end point of this study, 9 patients (81.8%) survived and 1 patient was lost to follow-up. The mean follow-up duration was 33.5 months.Although there is no consensus for the optimal treatment of this rare disease, radical surgery is considered to be the initial choice for localized lesion. Given the high malignancy, the majority of MNAC or mesonephric-like adenocarcinoma patients who underwent adjuvant chemotherapy received 4 to 8 cycles of carboplatin/paclitaxel as a first-line treatment after primary surgery with a median progression-free survival of 12 months. Treatment for recurrent disease in these patients included gemcitabine, carboplatin, and paclitaxel. Radiation was very limited in the treatment of the disease.

Mesonephric-like Differentiation of Endometrial Endometrioid Carcinoma: Clinicopathological and Molecular Characteristics Distinct from Those of Uterine Mesonephric-like Adenocarcinoma

When diagnosing endometrial carcinoma cases, we encountered histological features that strikingly resembled uterine mesonephric-like adenocarcinoma (MLA), but the differential diagnosis remained challenging after performing immunostaining. Considering the aggressive biological behavior and poor prognosis of uterine MLA, we believe that the accurate recognition of mesonephric-like differentiation (MLD) is important in the diagnosis of endometrial carcinoma. We aimed to investigate the clinicopathological and molecular characteristics of such cases and compared them with those of uterine MLAs. Five patients diagnosed with endometrioid carcinoma (EC) with MLD were included in this study. Histological evaluation, immunostaining, and targeted sequencing were performed. All five tumors showed typical morphological features of MLA, including densely aggregated tubular structures, deep basophilia under low-power magnification microscopy, eosinophilic intraluminal secretions, and diverse growth patterns. Immunostaining revealed moderate-to-strong nuclear immunoreactivity for estrogen and progesterone receptors in more than 50% tumor cells. The staining intensities and proportions of PAX2 and GATA3 were variable. None of the tumors harbored KRAS mutations. Considering the prognostic implications, ancillary tests, including immunostaining and targeted sequencing, should be performed to accurately differentiate between endometrial EC-MLD and uterine MLA.

Mesonephric and mesonephric-like carcinomas of the female genital tract: molecular characterization including cases with mixed histology and matched metastases

Mesonephric carcinoma of the cervix is a rare tumor derived from Wolffian remnants. Mesonephric-like carcinomas of the ovary and endometrium, while morphologically similar, do not have obvious Wolffian derivation. Here, we sought to characterize the repertoire of genetic alterations in primary mesonephric and mesonephric-like carcinomas, in the distinct histologic components of mixed cases, as well as in matched primary tumors and metastases. DNA from microdissected tumor and normal tissue from mesonephric carcinomas (cervix, n = 8) and mesonephric-like carcinomas (ovarian n = 15, endometrial n = 13) were subjected to sequencing targeting 468 cancer-related genes. The histologically distinct components of four cases with mixed histology and four primary tumors and their matched metastases were microdissected and analyzed separately. Mesonephric-like carcinomas were underpinned by somatic KRAS mutations (25/28, 89%) akin to mesonephric carcinomas (8/8, 100%), but also harbored genetic alterations more frequently reported in Müllerian tumors. Mesonephric-like carcinomas that lacked KRAS mutations harbored NRAS (n = 2, ovary) or BRAF (n = 1, endometrium) hotspot mutations. PIK3CA mutations were identified in both mesonephric-like (8/28, 28%) and mesonephric carcinomas (2/8, 25%). Only mesonephric-like tumors harbored CTNNB1 hotspot (4/28, 14%) and PTEN (3/13, 23%) mutations. Copy number analysis revealed frequent gains of chromosomes 1q and 10 in both mesonephric (87% 1q; 50% chromosome 10) and mesonephric-like tumors (89% 1q; 43% chromosome 10). Chromosome 12 gains were more frequent in ovarian mesonephric-like carcinomas, and losses of chromosome 9 were more frequent in mesonephric than in mesonephric-like carcinomas (both p = 0.01, Fisher's exact test). The histologically distinct components of four mixed cases were molecularly related and shared similar patterns of genetic alterations. The progression from primary to metastatic lesions involved the acquisition of additional mutations, and/or shifts from subclonal to clonal mutations. Our findings suggest that mesonephric-like carcinomas are derived from a Müllerian substrate with differentiation along Wolffian/mesonephric lines.

Clinicopathological Characteristics of Microscopic Tubal Intraepithelial Metastases from Adenocarcinoma and Small Cell Neuroendocrine Carcinoma of the Uterine Cervix

BACKGROUND/AIM

Some metastatic tumors that involve the fallopian tube show intraepithelial spread, mimicking primary tubal neoplasm and representing a potential diagnostic pitfall. In this study, we aimed to investigate the clinicopathological characteristics of tubal intraepithelial metastasis (IEM) from cervical carcinoma.

PATIENTS AND METHODS

We analyzed the clinical features, histological features, and immunophenotypes of IEMs in five patients with cervical carcinoma.

RESULTS

This study included usual-type (1/5), mucinous-type (1/5), and gastric-type (2/5) endocervical adenocarcinomas and small cell neuroendocrine carcinoma (1/5) cases. None of the patients had ovarian metastasis, but metastatic tumor cells spread along the tubal mucosal surface and partially replaced the lining epithelium. Histological features of metastatic tumors closely resembled those of the primary tumors in all cases.

CONCLUSION

Tubal IEM can mimic various tubal lesions including serous tubal intraepithelial carcinoma. Morphological consistency between the primary and metastatic tumors and immunostaining help guide the differential diagnosis of challenging intraepithelial lesions of the fallopian tube.

Clinicopathological Characteristics of Gastric-type Endocervical Adenocarcinoma Misdiagnosed as an Endometrial, Ovarian or Extragenital Malignancy, or Mistyped as Usual-type Endocervical Adenocarcinoma

BACKGROUND/AIM

The diagnosis of gastric-type endocervical adenocarcinoma (GEA) is challenging because its differential diagnosis includes not only gynecological tumors, but also extragenital tumors.

PATIENTS AND METHODS

We reviewed the electronic medical records and all available slides to investigate the clinicopathological characteristics of eight misdiagnosed GEA cases.

RESULTS

Three tumors were initially misdiagnosed as endometrial carcinoma. They displayed extensive endomyometrial involvement and complex glandular architecture, but no severe nuclear pleomorphism. Another three tumors were misclassified as usual-type endocervical adenocarcinoma because of mucin-poor, pseudoendometrioid glands, apical mitotic figures, and karyorrhectic debris. The two remaining tumors presenting as adnexal masses mimicked primary ovarian mucinous tumor and metastatic cholangiocarcinoma.

CONCLUSION

The varying pathological characteristics of GEA reflect the variability in clinical manifestations and its diagnostic difficulties. It is challenging to make an accurate diagnosis based solely on histological features. When suspecting GEA, clinicians should consider more comprehensively the clinicopathological context, along with immunostaining results.