Targeted genomic profiling reveals recurrent KRAS mutations and gain of chromosome 1q in mesonephric carcinomas of the female genital tract

Mesonephric-type adenocarcinomas of the ovary: prevalence, diagnostic reproducibility, outcome, and value of PAX2

Mesonephric-type (or -like) adenocarcinomas (MAs) of the ovary are an uncommon and aggressive histotype. They appear to arise through transdifferentiation from Müllerian lesions creating diagnostic challenges. Thus, we aimed to develop a histologic and immunohistochemical (IHC) approach to optimize the identification of MA over its histologic mimics, such as ovarian endometrioid carcinoma (EC). First, we screened 1,537 ovarian epithelial neoplasms with a four-marker IHC panel of GATA3, TTF1, ER, and PR followed by a morphological review of EC to identify MA in retrospective cohorts. Interobserver reproducibility for the distinction of MA versus EC was assessed in 66 cases initially without and subsequently with IHC information (four-marker panel). Expression of PAX2, CD10, and calretinin was evaluated separately, and survival analyses were performed. We identified 23 MAs from which 22 were among 385 cases initially reported as EC (5.7%) and 1 as clear cell carcinoma. The interobserver reproducibility increased from fair to substantial (κ = 0.376-0.727) with the integration of the four-marker IHC panel. PAX2 was the single most sensitive and specific marker to distinguish MA from EC and could be used as a first-line marker together with ER/PR and GATA3/TTF1. Patients with MA had significantly increased risk of earlier death from disease (hazard ratio = 3.08; 95% CI, 1.62-5.85; p < 0.0001) compared with patients with EC, when adjusted for age, stage, and p53 status. A diagnosis of MA has prognostic implications for stage I disease, and due to the subtlety of morphological features in some tumors, a low threshold for ancillary testing is recommended.

Ovarian Mesonephric-Like Adenocarcinoma With Recurrent Liver Metastases: A Case Report with Analysis of Therapeutic Molecular Targets

Ovarian mesonephric-like adenocarcinoma (MLA) is a rare cancer subtype. We describe a patient with ovarian MLA wherein liver metastases developed 1 month after surgery. A phenotypic analysis of the tumor was performed to identify molecular therapeutic targets. A 53-year-old woman, without any symptoms, underwent uterine cancer screening. Transvaginal ultrasonography revealed an ovarian mass, and subsequent pelvic magnetic resonance imaging showed a 13 × 10 cm multicystic ovarian lesion with a solid part. No extra ovarian lesions were observed and a staging laparotomy was performed. Pathological examination revealed an MLA of the left ovary (stage IC1). The tumor comprised tumor cells in a tubular pattern with intraluminal eosinophilic material, as well as mixed glandular and papillary, cord-like, and solid patterns. Endometriosis was also observed. Immunohistochemically, the tumor cells were positive for PAX8, GATA3 (focal), TTF1 (focal), and CD10 (luminal) and negative for the estrogen receptor, progesterone receptor, and WT1. One month after surgery, computed tomography revealed multiple liver metastases. Additional immunohistochemistry for therapeutic targets revealed that the tumor cells were weakly positive for human epidermal growth factor receptor 2 (focal; score 1+), pan-tropomyosin receptor kinase-negative, programmed death-ligand 1-negative, and PMS2 and MSH6 intact. The companion homologous recombination deficiency test (MyChoice®) showed homologous recombination repair proficiency. These findings suggest that poly(ADP-ribose) polymerase inhibitors and immune checkpoint inhibitors may not be effective treatment options. A literature review revealed that data on therapeutic targets in MLA are scarce. In summary, we report a patient with ovarian MLA showing an aggressive clinical course and the phenotypic analysis of the tumor may contribute to the identification of therapeutic targets for MLA.

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.

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.

Gain-of-function MYCN causes a megalencephaly-polydactyly syndrome manifesting mirror phenotypes of Feingold syndrome

MYCN, a member of the MYC proto-oncogene family, regulates cell growth and proliferation. Somatic mutations of MYCN are identified in various tumors, and germline loss-of-function variants are responsible for Feingold syndrome, characterized by microcephaly. In contrast, one megalencephalic patient with a gain-of-function variant in MYCN, p.Thr58Met, has been reported, and additional patients and pathophysiological analysis are required to establish the disease entity. Herein, we report two unrelated megalencephalic patients with polydactyly harboring MYCN variants of p.Pro60Leu and Thr58Met, along with the analysis of gain-of-function and loss-of-function Mycn mouse models. Functional analyses for MYCN-Pro60Leu and MYCN-Thr58Met revealed decreased phosphorylation at Thr58, which reduced protein degradation mediated by FBXW7 ubiquitin ligase. The gain-of-function mouse model recapitulated the human phenotypes of megalencephaly and polydactyly, while brain analyses revealed excess proliferation of intermediate neural precursors during neurogenesis, which we determined to be the pathomechanism underlying megalencephaly. Interestingly, the kidney and female reproductive tract exhibited overt morphological anomalies, possibly as a result of excess proliferation during organogenesis. In conclusion, we confirm an MYCN gain-of-function-induced megalencephaly-polydactyly syndrome, which shows a mirror phenotype of Feingold syndrome, and reveal that MYCN plays a crucial proliferative role, not only in the context of tumorigenesis, but also organogenesis.

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 Adenomyofibroma: A Biphasic Vaginal Mass of Mesonephric Type With Molecular Analysis: A Case Report of a Rare Entity

Mesonephric neoplasms of the lower female genital tract are rare. To date, there are scarce reports of benign biphasic vaginal mesonephric lesions, and none have included immunohistochemical and/or molecular analysis. A biphasic neoplasm of mesonephric-type was incidentally identified in the vaginal submucosal tissue of a 55-yr-old woman who underwent a right salpingo-oophorectomy for an ovarian cyst. The well-circumscribed, 5 mm nodule exhibited white-tan, firm homogenous cut surfaces. Microscopic examination showed a lobular arrangement of glands with columnar to the cuboidal epithelium and intraluminal eosinophilic secretions, embedded within a myofibromatous stroma. Cytologic atypia and mitotic activity were absent. Immunohistochemical staining for PAX8 and GATA3 demonstrated diffuse expression in the glandular epithelium, CD10 exhibited a patchy luminal expression pattern, while TTF1, ER, PR, p16, and NKX3.1 were negative. Desmin highlighted a subset of the stromal cells, but myogenin was negative. Whole exome sequencing demonstrated variants of unknown significance in multiple genes including PIK3R1 and NFIA . The morphologic and immunohistochemical profiles are consistent with a benign mesonephric neoplasm. This is the first report describing the immunohistochemical and whole exome sequencing results for a benign biphasic vaginal mesonephric neoplasm. To the best of our knowledge, benign mesonephric adenomyofibroma has not been previously reported in this anatomic location.

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.

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.

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.

Single-cell transcriptomics dissects epithelial heterogeneity in HPV+ cervical adenocarcinoma

The intra- and intertumoral heterogeneity of epithelial cells in human papillomavirus (HPV⁺ ) cervical adenocarcinoma (CEAD) remains largely unknown. To investigate this issue, we performed single-cell RNA sequencing on 19 229 epithelial cells sorted from three tumor samples of three patients with HPV⁺ CEAD. Six epithelial subclusters (Epi1-Epi6) were identified that showed distinct gene expression. Among these, Epi1 and Epi4 had apparent tumor hallmarks and metabolic activities. Epi1 was highly enriched in hallmarks of hypoxia, IL2/STAT5 signaling, retinol metabolism, glycolysis, and arachidonic acid metabolism, while Epi4 was highly enriched in hallmarks of G2M checkpoint, E2F targets, DNA repair, PI3K/AKT/MTOR signaling, glycolysis, fatty acid degradation, TCA cycle, and glutathione metabolism. We also investigated intertumoral epithelial heterogeneity and found that Patient 1 was highly enriched for KRAS signaling and angiogenesis, while Patient 2 was highly enriched for epithelial-mesenchymal transition and TGF-β signaling, and Patient 3 was highly enriched for hypoxia, DNA repair, G2M checkpoint, and E2F targets. Using single-cell RNA sequencing, we revealed the intra- and intertumoral heterogeneity of epithelial cells in HPV⁺ CEAD, providing insights into the importance of personalized treatment for patients with HPV⁺ CEAD.

S100A10 promotes HCC development and progression via transfer in extracellular vesicles and regulating their protein cargos

OBJECTIVE

Growing evidence indicates that tumour cells exhibit characteristics similar to their lineage progenitor cells. We found that S100 calcium binding protein A10 (S100A10) exhibited an expression pattern similar to that of liver progenitor genes. However, the role of S100A10 in hepatocellular carcinoma (HCC) progression is unclear. Furthermore, extracellular vesicles (EVs) are critical mediators of tumourigenesis and metastasis, but the extracellular functions of S100A10, particularly those related to EVs (EV-S100A10), are unknown.

DESIGN

The functions and mechanisms of S100A10 and EV-S100A10 in HCC progression were investigated in vitro and in vivo. Neutralising antibody (NA) to S100A10 was used to evaluate the significance of EV-S100A10.

RESULTS

Functionally, S100A10 promoted HCC initiation, self-renewal, chemoresistance and metastasis in vitro and in vivo. Of significance, we found that S100A10 was secreted by HCC cells into EVs both in vitro and in the plasma of patients with HCC. S100A10-enriched EVs enhanced the stemness and metastatic ability of HCC cells, upregulated epidermal growth factor receptor (EGFR), AKT and ERK signalling, and promoted epithelial-mesenchymal transition. EV-S100A10 also functioned as a chemoattractant in HCC cell motility. Of significance, S100A10 governed the protein cargos in EVs and mediated the binding of MMP2, fibronectin and EGF to EV membranes through physical binding with integrin αⅤ. Importantly, blockage of EV-S100A10 with S100A10-NA significantly abrogated these enhancing effects.

CONCLUSION

Altogether, our results uncovered that S100A10 promotes HCC progression significantly via its transfer in EVs and regulating the protein cargoes of EVs. EV-S100A10 may be a potential therapeutic target and biomarker for HCC progression.

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.

HPV-Negative Adenocarcinomas of the Uterine Cervix: From Molecular Characterization to Clinical Implications

Cervical cancer is the fourth most common cancer in women. It is the leading cause of female deaths in developing countries. Most of these cervical neoplasms are represented by squamous lesions. Cervical adenocarcinoma causes about a quarter of cervical cancers. In contrast to squamous lesions, cervical glandular disease is HPV-negative in about 15-20% of cases. HPV-negative cervical adenocarcinomas typically present in advanced stages at clinical evaluation, resulting in a poorer prognosis. The overall and disease-free survival of glandular lesions is lower than that of squamous lesions. Treatment options require definitive treatments, as fertility-sparing is not recommended. Moreover, the impact of HPV vaccination and primary HPV screening is likely to affect these lesions less; hence, the interest in this challenging topic for clinical practice. An updated review focusing on clinical and molecular characterization, prognostic factors, and therapeutic options may be helpful for properly managing such cervical lesions.

Mesonephric-Like Adenocarcinomas a Rare Tumor: The Importance of Diagnosis

Mesonephric-like adenocarcinomas (MLA) are rare neoplasms that arise in the uterine body and ovary and have been added to the World Health Organisation's recent 2020 classification of female genital cancers. The pathogenesis of MLA is unknown and it remains debated whether they represent mesonephric carcinomas (Wolffian) arising in the endometrium/ovary or endometrioid carcinomas (Müllerian) closely mimicking mesonephric carcinomas. Here we report the case of a 57-year-old woman with an initial misdiagnosis of endometrioid adenocarcinoma on diagnostic biopsy. The patient came to our clinical evaluation for the appearance of menometrorrhagia complicated by anemia for several months. Therefore, she underwent pelvic echo-flowmetry, with indication for diagnostic hysteroscopy with endometrial biopsy, which yielded a positive result for endometrioid endometrial adenocarcinoma. Following staging CT scan and targeted examinations on pulmonary findings, the patient underwent surgery with surprise of definitive diagnosis deponent for endometrial MLA. Our intention is to establish a brief review of the scientific evidence in the literature and the tools available for a correct histological diagnosis, in the light of the scant anatomopathological evidence. Our question gives rise to the motive for the publication: is immunohistochemistry the right way to resolve the diagnostic error at histology, which is usually the only source of diagnostic certainty? This case is intended to alert of diagnostic error that risked having the patient treated as a neoplasm with a favorable prognosis and low degree of aggressiveness instead of for a very aggressive and poor prognosis tumor such as MLA.

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.

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.

[Revised German guidelines on the diagnosis and treatment of carcinoma of the uterine cervix-what's new for pathologists in 2021?]

In 2021, the 2015 German consensus guideline for the diagnosis and treatment of uterine cervical carcinoma was updated. The present article summarises the new recommendations for pathologists: the incorporation of the International Endocervical Adenocarcinoma Classification (IECC), which morphologically separates HPV-associated and non-HPV-associated adenocarcinomas, as well as the reporting of the prognostic relevant growth pattern of the adenocarcinoma of the endocervical subtype (Silva pattern). Histologically, multifocality has been defined as the presence of clearly invasive foci with a minimum distance between each focus of 0.2 cm. Because of its intratumoural heterogeneity, all carcinomas ≤ 2 cm in their largest dimension should be processed completely, and tumours > 2 cm should be processed with one block per centimetre of their greatest dimension. In cases of (radical) trachelectomy/hysterectomy, the distal vaginal resection margin and all parametrial tissue should be processed completely. Sentinel lymph nodes have to be processed completely by lamellation along its long axis in 0.2 cm intervals. Immunohistochemical ultrastaging is mandatory. Staging should be performed using the 2009 FIGO classification and 2017 TNM classification. Reporting the revised 2018 FIGO classification is optional. To date, molecular markers have not been relevant for prognostication and treatment decision making.

Mesonephric-like Endometrial Carcinoma: Results From Immunohistochemical Screening of 300 Endometrial Carcinomas and Carcinosarcomas for This Often Overlooked and Potentially Aggressive Entity

Mesonephric-like endometrial carcinoma is a rare but frequently misclassified and aggressive malignancy. KRAS mutations, limited estrogen receptor (ER) expression, and TTF-1, GATA3, and luminal CD10 expression are described in these tumors, but an immunohistochemistry-based screening approach has not been studied. We assessed 300 endometrial carcinomas/carcinosarcomas to ascertain the specificity of TTF-1/GATA3/luminal CD10 expression with or without ER staining for this diagnosis. Next-generation sequencing and morphologic review were performed on screen-positive cases. In all, 3% (9/300) were TTF-1+; 2 coexpressed GATA3. No cases expressed luminal CD10 or GATA3 in isolation. Two TTF-1+/ER- cases, one of which was also GATA3+, were reclassified as mesonephric-like based on morphology and molecular results (KRAS mutations without mismatch repair deficiency, TP53 mutations, or PTEN mutations): these represented 0.7% of all cases (2/300). The reclassified cases were originally diagnosed as grade 1 and 2 endometrioid carcinoma, and the latter had pulmonary metastases and pelvic recurrences. Six TTF-1+ cases retained their original serous (3) and endometrioid (3) diagnoses; 1 was reclassified as dedifferentiated. All had negative or low ER. KRAS mutations were identified in 4 TTF-1+ non-mesonephric-like cases, including 1 serous and 1 grade 3 endometrioid with p53 abnormalities, 1 mismatch repair-deficient endometrioid with a complex molecular profile, and 1 endometrioid with mucinous differentiation. These findings suggest that TTF-1 and ER are good first-line screens for mesonephric-like carcinoma, but caution that a TTF-1+/ER- immunoprofile is not specific, even in the setting of KRAS mutations. A final diagnosis of mesonephric-like carcinoma requires integration of morphologic and immunohistochemical features, with molecular support when relevant.

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.

Molecular Evaluation of Low-grade Low-stage Endometrial Cancer With and Without Recurrence

Low-grade, low-stage endometrioid carcinomas (LGLS EC) demonstrate 5-yr survival rates up to 95%. However, a small subset of these tumors recur, and little is known about prognostic markers or established mutation profiles associated with recurrence. The goal of the current study was to identify the molecular profiles of the primary carcinomas and the genomic differences between primary tumors and subsequent recurrences. Four cases of LGLS EC with recurrence and 8 cases without recurrence were evaluated via whole-exome sequencing. Three of the 4 recurrent tumors were evaluated via Oncomine Comprehensive Assay. The resulting molecular profiles of the primary and recurrent tumors were compared. Two of the 3 recurrent cases showed additional mutations in the recurrence. One recurrent tumor included an additional TP53 mutation and the other recurrent tumor showed POLE and DDR2 kinase gene mutation. The POLE mutation occurred outside the exonuclease domain. PIK3CA mutations were detected in 4 of 4 primary LGLS EC with recurrence and in 3 of 8 disease-free cases. LGLS EC with recurrence showed higher MSIsensor scores compared with LGLS without recurrence. The level of copy number gains in LGLS EC with recurrence was larger than LGLS EC without recurrence. This pilot study showed 1 of 3 recurrent cases gained a mutation associated with genetic instability (TP53) and 1 of them also acquired a mutation in the DDR2 kinase, a potential therapeutic target. We also noted a higher level of copy number gains, MSIsensor scores and PIK3CA mutations in the primary tumors that later recurred.

The complex and often confusing history, histology and histogenesis of mesonephric, STK11 adnexal tumour and mesonephric-like neoplasms of the upper female genital tract (including broad ligament)

Mesonephric lesions in the female genital tract are uncommon, with those arising from the upper tract being much less frequent than those developing in the lower tract (mesonephric hyperplasia and carcinoma). The most common upper tract lesions include rete cyst/cystadenoma and female adnexal tumour of Wolffian origin (FATWO). The integration of morphological, immunohistochemical and molecular studies on FATWOs has enabled recognition of a novel entity, the STK11 adnexal tumour, which is often associated with Peutz-Jeghers syndrome (~50%) and frequently has a salivary gland morphology but an unknown origin. Similarly, 'mesonephric-like' adenocarcinoma, an entity with striking similarities to mesonephric carcinoma but currently favoured to be of Müllerian derivation based on its association with other Müllerian tumours and molecular findings, has also been recently described, and may histologically mimic both FATWOs and STK11 adnexal tumours. In this review, we provide a historical overview of upper female genital tract mesonephric proliferations and discuss mesonephric lesions, STK11 adnexal tumour, mesonephric-like adenocarcinoma, and mimickers, the most common being endometrioid carcinoma.

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 Adenocarcinoma of the Vagina Harboring TP53 Mutation

Mesonephric adenocarcinoma (MA) of the female genital tract is a rare but distinct entity, exhibiting unique morphological, immunophenotypical, and molecular characteristics. Vaginal MA is hypothesized to arise from the mesonephric remnants located in the lateral vaginal wall. A 52-year-old woman presented with vaginal bleeding. Physical examination revealed a protruding mass in the left vaginal wall. Pelvic magnetic resonance imaging revealed a 2.5-cm mass arising from the left upper vagina and extending posterolaterally to the extravaginal tissue. The punch biopsy was diagnosed as poorly differentiated adenocarcinoma. She received radical surgical resection. Histologically, the tumor displayed various architectural patterns, including compactly aggregated small tubules, solid cellular sheets, endometrioid-like glands and ducts, intraluminal micropapillae, cribriform structure, and small angulated glands accompanied by prominent desmoplastic stroma. The tubules and ducts possessed hyaline-like, densely eosinophilic intraluminal secretions. The tumor extended to the subvaginal soft tissue and had substantial perineural invasion. Immunostaining revealed positivity for the mesonephric markers, including GATA3, TTF1, and PAX2, while showing very focal and weak positivity for estrogen receptor and negativity for progesterone receptor. Additionally, we observed a complete absence of p53 immunoreactivity. Targeted sequencing analysis revealed that the tumor harbored both activating KRAS p.G12D mutation and truncating TP53 p.E286* mutation. A thorough review of the previous literature revealed that 4.5% (3/67) of vaginal/cervical MAs and 0.9% (1/112) of uterine/ovarian mesonephric-like adenocarcinomas harbor TP53 mutations, indicating that this is very uncommon in malignant mesonephric lesions. In summary, we presented a rare case of vaginal MA uniquely harboring pathogenic TP53 mutation, resulting in p53 aberration.

Molecular Pathology of Human Papilloma Virus-Negative Cervical Cancers

Cervical cancer is the fourth most common cancer in women worldwide and is predominantly caused by infection with human papillomavirus (HPV). However, a small subset of cervical cancers tests negative for HPV, including true HPV-independent cancers and false-negative cases. True HPV-negative cancers appear to be more prevalent in certain pathological adenocarcinoma subtypes, such as gastric- and clear-cell-type adenocarcinomas. Moreover, HPV-negative cervical cancers have proven to be a biologically distinct tumor subset that follows a different pathogenetic pathway to HPV-associated cervical cancers. HPV-negative cervical cancers are often diagnosed at an advanced stage with a poor prognosis and are expected to persist in the post-HPV vaccination era; therefore, it is important to understand HPV-negative cancers. In this review, we provide a concise overview of the molecular pathology of HPV-negative cervical cancers, with a focus on their definitions, the potential causes of false-negative HPV tests, and the histology, genetic profiles, and pathogenesis of HPV-negative cancers.

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.

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.

Napsin-A and AMACR are Superior to HNF-1β in Distinguishing Between Mesonephric Carcinomas and Clear Cell Carcinomas of the Gynecologic Tract

Mesonephric carcinoma is a rare gynecologic neoplasm commonly mistaken for clear cell carcinoma, because of their overlapping morphologic features. Both tumors are negative for estrogen receptor and p16, magnifying this diagnostic dilemma. Recently, hepatocyte nuclear factor-1 beta (HNF-1β), a marker for clear cell carcinoma, has also been shown to be positive in mesonephric carcinomas. Other more recent markers for clear cell carcinoma, however, such as Napsin-A and alpha-methylacyl-CoA racemase (AMACR), have not yet been studied in mesonephric carcinomas. Here we examine HNF-1β, AMACR, and Napsin-A immunohistochemistry in 18 mesonephric and 55 endometrial/cervical clear cell carcinomas. HNF-1β was considered positive if nuclear staining was present in ≥70% of cells and at least moderate intensity; for Napsin-A and AMACR, any cytoplasmic staining was considered positive (≥1%). H-scores were determined by multiplying the intensity score by proportion score. HNF-1β was positive in a substantial portion of mesonephric carcinomas (9/18, 50%; H-score 98) and clear cell carcinomas (34/55, 62%; H-score 163) and did not distinguish between the 2 entities (specificity, 50%; P-value of H-score=0.08). Napsin-A and AMACR expression was significantly higher in clear cell [43/55 (78%) and 41/55 (75%), respectively] than mesonephric carcinomas [4/18 (22%) and 4/18 (22%) respectively], and helpful in this differential (specificity: 78% and 78%; P<0.05 for both). When Napsin-A and AMACR staining were seen in mesonephric carcinomas, staining was focal (≤5%), whereas staining in clear cell carcinomas was patchy/diffuse. In summary, Napsin-A and AMACR are helpful in distinguishing mesonephric carcinomas from clear cell carcinomas of the female genital tract, but HNF-1β is not.

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.

A Distinctive Adnexal (Usually Paratubal) Neoplasm Often Associated With Peutz-Jeghers Syndrome and Characterized by STK11 Alterations (STK11 Adnexal Tumor): A Report of 22 Cases

We describe 22 examples of a novel, usually paratubal, adnexal tumor associated with Peutz-Jeghers syndrome in nearly 50% of cases that harbored STK11 alterations in all tested (n=21). The patients ranged from 17 to 66 years (median=39 y) and the tumors from 4.5 to 25.5 cm (median=11 cm). Most (n=18) were paratubal, with metastases noted in 11/22 (50%) and recurrences in 12/15 (80%). Morphologically, they were characterized by interanastomosing cords and trabeculae of predominantly epithelioid cells, set in a variably prominent myxoid to focally edematous stroma, that often merged to form tubular, cystic, cribriform, and microacinar formations, reminiscent of salivary gland-type tumors. The tumor cells were uniformly atypical, often with prominent nucleoli and a variable mitotic index (median=9/10 HPFs). The tumors were usually positive to a variable extent for epithelial (CAM5.2, AE1/AE3, cytokeratin 7), sex cord (calretinin, inhibin, WT1), and mesothelial (calretinin, D2-40) markers, as well as hormone receptors. PAX8, SF1, and GATA-3 were rarely positive, while claudin-4, FOXL2, and TTF-1 were consistently negative. All sequenced tumors (n=21) harbored alterations in STK11, often with a loss of heterozygosity event. There were no other recurrently mutated genes. Recurrent copy number alterations included loss of 1p and 11q, and gain of 1q, 15q, and 15p. Despite an extensive morphologic, immunohistochemical, and molecular evaluation, we are unable to determine with certainty the histogenesis of this unique tumor. Wolffian, sex cord stromal, epithelial, and mesothelial origins were considered. We propose the term STK11 adnexal tumor to describe this novel entity and emphasize the importance of genetic counseling in these patients as a significant number of neoplasms occur in association with Peutz-Jeghers syndrome.

Extrauterine Mesonephric-like Neoplasms: Expanding the Morphologic Spectrum

Mesonephric-like adenocarcinomas (MLA) are rare neoplasms arising in the uterine corpus and ovary which have been added to the recent 2020 World Health Organization Classification of Female Genital Tumors. They have similar morphology and immunophenotype and exhibit molecular aberrations similar to cervical mesonephric adenocarcinomas. It is debated as to whether they are of mesonephric or Mullerian origin. We describe the clinical, pathologic, immunohistochemical, and molecular features of 5 cases of extrauterine mesonephric-like proliferations (4 ovary, 1 extraovarian), all with novel and hitherto unreported features. These include an origin of MLA in extraovarian endometriosis, an association of ovarian MLA with high-grade serous carcinoma, mixed germ cell tumor and mature teratoma, and a borderline ovarian endometrioid tumor exhibiting mesonephric differentiation. Four of the cases exhibited a KRAS variant and 3 also a PIK3CA variant. In reporting these cases, we expand on the published tumor types associated with MLA and report for the first time a borderline tumor exhibiting mesonephric differentiation. We show the value of molecular testing in helping to confirm a mesonephric-like lesion and in determining the relationship between the different neoplastic components. We provide further evidence for a Mullerian origin, rather than a true mesonephric origin, in some of these cases. We also speculate that in the 2 cases associated with germ cell neoplasms, the MLA arose out of the germ cell tumor.

Atypical Mesonephric Hyperplasia of the Uterus Harbors Pathogenic Mutation of Kirsten Rat Sarcoma 2 Viral Oncogene Homolog (KRAS) and Gain of Chromosome 1q

BACKGROUND/AIM

Mesonephric carcinoma (MNC) is a rare but notable entity of the female genital tract. While many researchers have acknowledged and studied MNC, much remains unknown on the characteristics of mesonephric remnant (MNR) or hyperplasia (MNH). There has not been any study examining the molecular features of MNR and MNH so far. The aim of this study was to investigate the clinicopathological and molecular characteristics of ten uterine mesonephric lesions, including two MNRs without atypia, four MNHs without atypia, and three MNHs with atypia.

MATERIALS AND METHODS

We reviewed the electronic medical records and all available slides of ten cases from multiple institutions. Targeted sequencing and array comparative genomic hybridization were performed.

RESULTS

Three atypical MNHs displayed nuclear enlargement, mild-to-moderate nuclear pleomorphism, and nuclear membrane irregularity, and harbored pathogenic Kirsten rat sarcoma 2 viral oncogene homolograt sarcoma 2 viral oncogene homolog (KRAS) mutation. Two of those that co-existed with MNC harbored the same sequence alterations as each of their adjacent MNC. One of the three atypical MNHs harbored chromosome 1q gain.

CONCLUSION

Atypical MNH is a potential premalignant lesion in which KRAS mutation and chromosome 1q gain play an important role in the early stage of mesonephric carcinogenesis.

HPV-Negative Cervical Cancer: A Narrative Review

Cervical cancer (CC) is the fourth most frequent cancer in women worldwide. HPV infection is associated with the majority of CC cases, but a small proportion of CCs actually test negative for HPV. The prevalence of HPV among CC histotypes is very different. It has been suggested that HPV-negative CC may represent a biologically distinct subset of tumors, relying on a distinct pathogenetic pathway and carrying a poorer prognosis, than HPV-positive CCs. Although, the discordance in terms of sensitivity and specificity between different HPV tests as well as the potential errors in sampling and storing tissues may be considered as causes of false-negative results. The identification of HPV-negative CCs is essential for their correct management. The aim of this narrative review is to summarize the clinical and pathological features of this variant. We also discuss the pitfalls of different HPV tests possibly leading to classification errors.

Mesonephric (Wolffian-derived) Adenocarcinoma of the Female Urethra

The current World Health Organization (WHO) classification of adenocarcinoma of the urinary tract including the urethra includes uncommon Müllerian-derived carcinomas such as clear cell and endometrioid adenocarcinomas. The concept of primary mesonephric (Wolffian-derived) adenocarcinoma (MA) in the urethra (and urinary tract in general) is currently regarded as controversial as the term "mesonephric" had been also inaccurately applied in the past to label Müllerian-derived carcinomas, particularly clear cell adenocarcinoma. Further, pathologically well-documented or bona fide urethral MAs have not yet to be reported. Herein, we describe 2 examples of MA in elderly females that primarily presented in the urethra and manifested clinically with obstructive lower urinary tract symptoms. Both tumors exhibited histology similar to those in MAs of the female genital tract including the distinctive tubular proliferations with luminal eosinophilic materials. The first case, in addition, showed a variety of patterns including ductal (glandular), solid, fused/sieve-like tubules, dilated tubules, and spindled cells. The second case also showed a transition to the more irregular and poorly formed tubular proliferation of cells with greater nuclear atypia and with a desmoplastic response. Both tumors showed positivity for PAX8, GATA3, and luminal CD10, and 1 tumor analyzed harbored KRAS and ARID1A mutations. One patient received neoadjuvant chemotherapy and underwent resection but had local tumor recurrence and metastasis to the lungs and lumbar spine 12 months after presentation. In conclusion, MA, similar to those occurring in the female genital tract and distinct from the recognized Müllerian-derived carcinomas, may present primarily as urethral tumors. MA in the urethra probably shares a common pathogenesis with vaginal MA as both may originate from the same caudal loci of mesonephric remnants along the closely apposed anterior vaginal and posterior urethral walls. MA should be considered in future classifications for urethral tumors and we recommend that the confusing term "mesonephroid adenocarcinoma" should no longer be used.

Serous Carcinoma of the Endometrium with Mesonephric-Like Differentiation Initially Misdiagnosed as Uterine Mesonephric-Like Adenocarcinoma: A Case Report with Emphasis on the Immunostaining and the Identification of Splice Site TP53 Mutation

We present herein a rare case of uterine serous carcinoma with mesonephric-like differentiation (SC-MLD) initially misdiagnosed as mesonephric-like adenocarcinoma (MLA). A 51-year-old woman underwent total hysterectomy for a uterine tumor. Histologically, the tumor exhibited various architectures, including papillary, glandular, tubular, cribriform, and cystic. On the basis of this architectural diversity accompanied by intraluminal eosinophilic secretions and intermediate-grade nuclear atypia, the initial diagnosis was MLA. However, the tumor was diffusely and strongly positive for the expression of p16 and negative for the expression of GATA-binding protein 3 (GATA3). Furthermore, we identified a pathogenic tumor protein 53 (TP53) mutation affecting an acceptor splice site in intron 9, despite a wild-type p53 immunostaining pattern. The observations of diffuse and strong p16 expression, lack of GATA3 expression, pathogenic TP53 mutation, and wild-type Kirsten rat sarcoma viral oncogene homolog indicate that this tumor was not an MLA but an SC-MLD. Both uterine SC and MLA can exhibit various histological growth patterns. Our comprehensive clinicopathological and molecular analyses can serve to improve the understanding of this rare condition and help pathologists in making an accurate diagnosis.

Clinicopathologic Characteristics of Mesonephric Adenocarcinomas and Mesonephric-like Adenocarcinomas in the Gynecologic Tract: A Multi-institutional Study

Mesonephric adenocarcinoma (MA) and mesonephric-like adenocarcinoma (MLA) are uncommon neoplasms of the gynecologic tract that have until recently been poorly understood. Although their morphologic, immunohistochemical, and molecular profiles have been recently defined, little is known about their clinical behavior. Small studies have demonstrated inconsistent findings and no large studies have examined the clinical behavior of these adenocarcinomas. In this multi-institutional study, representing the largest and most stringently defined cohort of cases to date, we examined the clinicopathologic features of 99 MAs and MLAs (30 MAs of the uterine cervix, 44 MLAs of the endometrium, and 25 MLAs of the ovary). Only tumors with characteristic mesonephric morphology and either immunohistochemical or molecular support were included. Our results demonstrate that the majority of mesonephric neoplasms presented at an advanced stage (II to IV) (15/25 [60%] MA of the cervix, 25/43 [58%] MLA of the endometrium, and 7/18 [39%] MLA of the ovary). The majority (46/89 [52%] overall, 12/24 [50%] MA of the cervix, 24/41 [59%] MLA of the endometrium, and 10/24 [42%] MLA of the ovary) developed recurrences, most commonly distant (9/12 [75%] MA of the cervix, 22/24 [92%] MLA of the endometrium, and 5/9 [56%] MLA of the ovary). The 5-year disease-specific survival was 74% (n=26) for MA of cervix, 72% (n=43) for MLA of endometrium, and 71% (n=23) for MLA of ovary. Our results confirm that mesonephric neoplasms are a clinically aggressive group of gynecologic carcinomas that typically present at an advanced stage, with a predilection for pulmonary recurrence.

Cervical malignant mixed mesonephric tumour: A case report with local recurrence after six-years and next-generation sequencing analysis with particular reference to the ataxia telangiectasia mutated gene

Malignant mixed mesonephric tumours (MMMsT) of the female genital tract are extremely rare, and the majority are located in the wall of the cervix uteri. At present, there are no reports of the molecular characterisation of MMMsT of the female genital tract. Herein, we report the morphological, immunohistochemical and molecular features of this rare malignancy using next-generation sequencing (NGS) analysis. A 58-year-old woman presented with vaginal bleeding. In 2013, she had been diagnosed with a cervical carcinosarcoma of probable mesonephric origin and International Federation of Gynaecology and Obstetrics (FIGO) stage IB that had been treated by total hysterosalpingo-oopherectomy without adjuvant chemo-radiotherapy. Ultrasonography showed a vaginal mass measuring 25 mm in the maximum dimension. Biopsy was performed and showed a biphasic neoplasm composed of adenocarcinoma and sarcoma. Immunohistochemistry showed positive staining for epithelial membrane antigen (EMA), pancytokeratin (MNF116), paired box 8 (PAX-8), β-catenin, cytokeratin 7, cyclin D1, GATA3 and CD10. Androgen receptor positivity was detected in very limited areas. Cytokeratin 20, carcinoembryonic antigen (CEA), oestrogen receptor (ER), progesterone receptor (PR), transcription termination factor 1 (TTF1), Wilm's tumour antigen-1 (WT-1), calretinin and p16 were negative. The immunohistochemical profile was consistent with mesonephric origin. NGS analysis identified a variant of the ataxia-telangiectasia mutated (ATM) gene (p.Phe858Leu; c.2572 T>C; COSM21826). The number of detected allele frequency reads of ATM mutation following clinical relapse was higher, compared to its baseline: 65 vs. 96%. The differential diagnosis of MMMsT includes mesonephric hyperplasia, malignant mixed Mullerian tumour (carcinosarcoma), endometrioid adenocarcinoma and endometrial stromal sarcoma. The clinical significance of the observed ATM variant in the case reported herein is unknown. The present findings need further verification, as the mutation in ATM may result in chemotherapy resistance or conversely, may be exploited for targeted therapies.

Tumor Typing of Endocervical Adenocarcinoma: Contemporary Review and Recommendations From the International Society of Gynecological Pathologists

The incidence of endocervical adenocarcinoma, the second most common cervical cancer in the world, has been on the rise. While most cervical cancers are squamous cell carcinomas and associated with high-risk oncogenic human papillomavirus (HPV), approximately 15% of endocervical adenocarcinomas, which now represent about one quarter of all cervical cancers, are HPV-independent. In this review, we will focus on the shortcomings of historical histologic classification systems of female genital tract tumors as they pertain to endocervical adenocarcinomas, and we will highlight the advantages of the new International Endocervical Adenocarcinoma Criteria and Classification system, which forms the basis for the WHO 2020 classification. We will cover the various histologic types, subtypes, and variants of endocervical adenocarcinoma with regard to morphology, immunophenotype, molecular genetics, HPV status and differential diagnosis, and we will provide International Society of Gynecological Pathologists recommendations for diagnosing these tumors.

Human Papillomavirus-Negative Cervical Cancer: A Comprehensive Review

Human papillomavirus (HPV) has been the leading cause of cervical cancer for over 25 years. Approximately 5.5–11% of all cervical cancers are reported to be HPV-negative, which can be attributed to truly negative and false-negative results. The truly HPV-negative cervical cancers are almost all cervical adenocarcinomas with unclear etiology. False HPV negativity can arise from histological misclassification, latent HPV infection, disruption of the targeting fragment, non-high risk HPV infection, and HPV testing methods. HPV-negative cervical cancers are often diagnosed at an advanced FIGO stage and have a poor prognosis; thus, the management of these cases requires greater attention.

Mesonephric-Like Adenocarcinoma of the Endometrium: Diagnostic Advances to Spot This Wolf in Sheep's Clothing. A Review of the Literature

Mesonephric-like adenocarcinoma is a recently described rare neoplasm occurring in the uterine corpus and ovary. This under-recognized subtype of carcinoma can be very challenging to diagnose. In mesonephric adenocarcinoma a variety of growth patterns can be present within the same tumor, as a result of which they can be misinterpreted and diagnosed as low-grade endometrioid adenocarcinoma, clear cell carcinoma, or even serous carcinoma and carcinosarcoma. We report a case of mesonephric-like adenocarcinoma misdiagnosed as a low-grade endometrioid endometrial adenocarcinoma that had an early local recurrence and metastasized to the liver and the lungs. Histopathological, immunohistochemical and molecular analysis were performed and compared to published literature, providing a comprehensive overview of the current knowledge. Databases (Pubmed, Web of Science, Google Scholar) were searched with a combination of the following search terms: mesonephric-like, mesonephric, adenocarcinoma, carcinoma, uterine body, uterine corpus, endometrium. Mesonephric-like adenocarcinoma is a difficult-to-diagnose entity. Advanced diagnostics, including improved morphologic, immunohistochemical and molecular knowledge can help develop new therapeutic strategies against this specific subtype of endometrial cancer with an aggressive clinical behavior.

Re-assigning the histologic identities of COV434 and TOV-112D ovarian cancer cell lines

OBJECTIVE

The development of effective cancer treatments depends on the availability of cell lines that faithfully recapitulate the cancer in question. This study definitively re-assigns the histologic identities of two ovarian cancer cell lines, COV434 (originally described as a granulosa cell tumour) and TOV-112D (originally described as grade 3 endometrioid carcinoma), both of which were recently suggested to represent small cell carcinoma of the ovary, hypercalcemic type (SCCOHT), based on their shared gene expression profiles and sensitivity to EZH2 inhibitors.

METHODS

For COV434 and TOV-112D, we re-reviewed the original pathology slides and obtained clinical follow-up on the patients, when available, and performed immunohistochemistry for SMARCA4, SMARCA2 and additional diagnostic markers on the original formalin-fixed, paraffin-embedded (FFPE) clinical material, when available. For COV434, we further performed whole exome sequencing and validated SMARCA4 mutations by Sanger sequencing. We studied the growth of the cell lines at baseline and upon re-expression of SMARCA4 in vitro for both cell lines and evaluated the serum calcium levels in vivo upon injection into immunodeficient mice for COV434 cells.

RESULTS

The available morphological, immunohistochemical, genetic, and clinical features indicate COV434 is derived from SCCOHT, and TOV-112D is a dedifferentiated carcinoma. Transplantation of COV434 into mice leads to increased serum calcium level. Re-expression of SMARCA4 in either COV434 and TOV-112D cells suppressed their growth dramatically.

CONCLUSIONS

COV434 represents a bona fide SCCOHT cell line. TOV-112D is a dedifferentiated ovarian carcinoma cell line.

Cytohistopathologic correlation of ovarian mesonephric-like carcinoma and female adnexal tumor of probable Wolffian origin

Recently we encountered two cases with mesonephric features, mesonephric-like carcinoma (MLC) of the ovary, and female adnexal tumor of probable Wolffian origin (FATWO). They are thought to be related to mesonephric remnants (or Wolffian duct remnants). Herein we describe the cytohistolgical features, differential diagnoses, and potential pitfalls in diagnosis of these neoplasms. On cytological examination, the case of MLC showed tight 3-dimensional clusters of overlapping round cells, corresponding to solid growth pattern seen on histological examination. Tubular architecture and papillary formations composed of neoplastic cells of medium size with scant cytoplasm were readily identified. Intraluminal eosinophilic secretions were better seen on histological examination. Additionally, areas resembling features of papillary thyroid carcinoma were noted. Mitoses and apoptotic bodies were not identified on cytology but seen on histological sections. The neoplastic cells were positive for CK7, CD10, PAX-8, TTF-1, and GATA-3, and negative for ER, PR, and WT-1 immunostains. In contrast to MLC, cytological examination of FATWO showed smaller oval to spindle monotonous cells without mitotic figures. Some cells contained paranuclear vacuoles and were arranged individually or in loose cohesive clusters. Other cells were closely associated with pericellular hyalinized basement membrane-like material and they were arranged in cohesive clusters as well. On histological examination, similar to MLC, the FATWO had areas with thyroid-like features, such as, intraluminal eosinophilic secretions, paranuclear vacuoles, in the background of collagenous stroma. The neoplastic cells were positive for CK AE1/AE3, calretinin, WT-1, inhibin, and CD10, and negative for CK7, PAX-8, GATA-3, ER, PR, and C-kit immunostains.

Mesonephric-like adenocarcinoma of the ovary: A case report and a review of the literature

RATIONALE

Mesonephric-like adenocarcinoma (MLA) from ovary is a very rare tumor which derives from mesonephric duct remnant of the female genital tract. Only six cases have been reported so far in the English literature.

PATIENT CONCERNS

A 29-year-old female patient was referred to the local hospital with a 20-day history of abdominal discomfort.

DIAGNOSES

Pelvic ultrasound examination revealed a solid and cystic mass measuring 10 cm in diameter in the right adnexal area and a cystic mass measuring 5 cm in the left adnexal area. Postoperative pathology in the local hospital revealed suspected malignancy of the right ovary, and she was then transferred to our institution for definite diagnosis. The tumor mass was finally diagnosed as a primary MLA arising from the right ovary by histological and immunohistochemical examination in our institution.

INTERVENTIONS

The patient underwent laparoscopic right adnexectomy and removal of left ovarian cyst in the local institution. Then, she underwent a complete staging surgery including a total hysterectomy, left adnexectomy, pelvic plus para-aortic lymphadenectomy, and omentectomy in our hospital. In addition, she received four cycles of combination chemotherapy with carboplatin plus paclitaxel.

OUTCOMES

There is no evidence of recurrence with 13 months of follow-up till now, and we are still following-up this patient.

LESSONS

MLA is an extremely uncommon malignancy with difficult diagnosis, unclear treatment and poor prognosis. Familiarizing with the clinical features and optimal management of this rare tumor may increase awareness of the disease among clinicians and pathologists, thus avoiding the misdiagnosis and mistreatment.

Remodeling of the ARID1A tumor suppressor

In recent years, AT-rich interactive domain-containing protein 1A (ARID1A) has been widely accepted as a bona fide tumor suppressor due to its essential role in preventing tumorigenesis and tumor progression in both mouse and human contexts. ARID1A shows high mutation frequencies in both cancers and preneoplastic lesions. The loss of ARID1A expression in cancer cells leads to increases in cell proliferation, invasion and migration and reductions in cell apoptosis and chemosensitivity. The tumor-suppressive role of ARID1A is mainly attributed to its regulation of gene transcription, which can be induced either directly by chromatin remodeling or indirectly by affecting histone modifications. ARID1A also acts independently of its cardinal transcription-regulating mechanisms, which include interfering with protein-protein interactions. Interestingly, nonmutational mechanisms, such as regulation by DNA hypermethylation, microRNAs, and ubiquitinases/deubiquitinases, have provided another perspective on ARID1A inactivation in cancer. Since the critical tumor-suppressive role of ARID1A has been revealed, several studies have attempted to identify synthetic lethal targets with ARID1A mutation/inactivation as an alternative strategy for cancer treatment.