Mesonephric-like Carcinoma of the Endometrium: A Subset of Endometrial Carcinoma With an Aggressive Behavior

Endometrial Mesonephric-like Adenocarcinoma Presenting as an Ocular Lesion: A Case Report

Endometrial mesonephric-like carcinoma (ML-CA) is a recently recognized subtype of aggressive endometrial adenocarcinoma that is morphologically and immunophenotypically similar to mesonephric carcinoma but not typically associated with mesonephric remnants. Here, we report a case of 58-yr-old female who had a past medical history of fibroids and of irregular menstrual bleeding for ~20 yr who presented with visual disturbance. On further investigation, she was found to have a large choroidal peri-papillary tumor of the right eye. A presumptive diagnosis of choroidal melanoma was made. Right eye enucleation was performed, and microscopy revealed moderately differentiated metastatic adenocarcinoma. Further work up was advised. A uterine mass was identified on imaging followed by endometrial biopsy that showed a morphologically and immunohistochemically similar tumor to that in the eye. A hysterectomy was carried out and a malignant neoplasm with varying morphologic patterns including gland formation, solid sheets of tumor cells, cribriform, glomeruloid, spindled and papillary areas was seen. The immunohistochemical profile showed diffuse strong positivity for AE1/AE3, TTF1, P16, and vimentin. CD56, GATA3, Napsin A, and CD10 were focally positive. The neoplastic cells were negative for the following markers ER, PR, WT1, calretinin, and synaptophysin. PDL-1 was negative and mismatch repair protein was proficient. An identical KRAS mutation was detected in both the uterine corpus and ocular tumors. The findings are in keeping with a uterine mesonephric-like adenocarcinoma with an ocular metastasis. An Oncomine Focus-Mutation profile, Thermo-Fisher Scientific Inc., a 60 gene oncologic panel, performed on the ocular tumor, revealed no further mutations.

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.

Immunohistochemistry in gynecologic carcinomas: Practical update with diagnostic and clinical considerations based on the 2020 WHO classification of tumors

This review provides an update on immunohistochemistry applications-diagnostic, prognostic, and predictive-in the pathology evaluation of gynecologic carcinomas. The 5th edition of the WHO Classification of Female Genital Tumors introduced important changes in the diagnostic classification of lower genital tract, endometrial, and ovarian carcinomas, with major influence on the routine pathology practice. Lower genital tract carcinomas and their precursor lesions are now classified based on their human papillomavirus (HPV)-associated and HPV-independent pathogenesis, reflecting the clinically significant prognostic differences and impacting the therapeutic decision-making. Immunohistochemical markers have an increasing role in the pathology evaluation of endometrial carcinomas: in addition to their traditional use in the differential diagnosis and histologic subtyping, they have also been recently advocated for prognostic classification as surrogates for the TCGA (The Cancer Genome Atlas) molecular groups. New entities - mesonephric-like adenocarcinoma and gastric (gastrointestinal)-type mucinous adenocarcinoma of the endometrium - have also been added and often require immunostains for diagnostic confirmation. Ovarian carcinomas frequently show overlapping morphologic patterns and heterogeneous appearance within the same tumor, necessitating immunohistochemical work-up. Beyond diagnostic applications, there is increasing clinical demand for screening of inherited cancer syndromes, prediction of prognosis and guiding targeted therapy. Practical issues and pitfalls related to mismatch repair protein immunohistochemistry, HER2, and PD-L1 testing are also discussed.

Management of locally advanced mesonephric carcinoma of the cervix in the setting of Mullerian Duct anomaly spectrum and unilateral renal agenesis: A case report and review of the literature

Cervical mesonephric adenocarcinoma is a rare histologic cervical carcinoma variant arising from remnants of the mesonephric duct. Few clinical cases have been reported in the literature, and given the low rate of occurrence, the optimal management strategy is unknown. Most reported cases involve patients with either early stage (FIGO I) or metastatic disease. Herein, we report the only known case of locally advanced, node-positive cervical mesonephric carcinoma in a 55-year old woman with Mullerian duct anomaly of the uterus, obstructed hemivagina, and ipsilateral renal agenesis. To our knowledge, this would be the first case report with the concurrence of both rare entities. We review the treatment paradigm in this patient, and the literature, including radiotherapy and brachytherapy techniques.

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.

Sustained response to lenvatinib and pembrolizumab in two patients with KRAS-mutated endometrial mesonephric-like adenocarcinoma

•Endometrial mesonephric-like adenocarcinoma (MLA) is a rare and aggressive subtype of epithelial endometrial cancer.•KRAS mutations are characteristic in patients with endometrial MLA.•We report two cases of KRAS-mutated endometrial MLA with excellent and durable responses to lenvatinib and pembrolizumab.•Tumors with KRAS mutations may be particularly sensitive to lenvatinib, but this warrants further study.

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.

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.

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.

[Current WHO classification of the female genitals : Many new things, but also some old]

The new WHO classification of tumors of the female genitalia entails some changes, especially those of prognostic and therapeutic relevance: there is a return to the term borderline tumor. Implants are again subdivided into noninvasive implants of the epithelial or desmoplastic type as before. Invasive extraovarian implants are classified as low-grade serous carcinoma (LGSC). Former seromucinous carcinomas are now classified as endometrioid carcinomas (seromucinous subtype). New entities of ovarian carcinomas are mesonephric-like adenocarcinoma, undifferentiated and dedifferentiated carcinoma, and mixed carcinoma. The classification of neuroendocrine neoplasms is analogous to that of pulmonary and gastrointestinal neuroendocrine neoplasms, regardless of their location. Endometrioid endometrial carcinoma can be classified into four molecular subtypes, which have significant prognostic significance. New subtypes include mucinous carcinoma of the intestinal type and mesonephric-like adenocarcinoma. Stromasarcomas of the endometrium are further subclassified based on specific molecular alterations. Adenocarcinomas (ACs) and squamous cell carcinomas (PECs) of the lower female genital tract are distinguished from HPV-associated and HPV-independent carcinomas. Block-like staining for p16 is the accepted surrogate immunohistochemical marker. Grading has not been reported for PEC. For HPV-associated AC of the cervix uteri, prognostic assessment is based on the pattern of invasion (so-called Silva pattern). Serous carcinomas in the cervix uteri are endometrial carcinomas with cervical infiltration.

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.

Development and Carcinogenesis: Roles of GATA Factors in the Sympathoadrenal and Urogenital Systems

The GATA family of transcription factors consists of six proteins (GATA1-6) that control a variety of physiological and pathological processes. In particular, GATA2 and GATA3 are coexpressed in a number of tissues, including in the urogenital and sympathoadrenal systems, in which both factors participate in the developmental process and tissue maintenance. Furthermore, accumulating studies have demonstrated that GATA2 and GATA3 are involved in distinct types of inherited diseases as well as carcinogenesis in diverse tissues. This review summarizes our current knowledge of how GATA2 and GATA3 participate in the transcriptional regulatory circuitry during the development of the sympathoadrenal and urogenital systems, and how their dysregulation results in the carcinogenesis of neuroblastoma, renal urothelial, and gynecologic cancers.

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.

Endometrial carcinoma: molecular subtypes, precursors and the role of pathology in early diagnosis

Endometrial carcinoma (EC) is classified into a wide range of morphological variants; this list has expanded over the past decade with the inclusion of mesonephric-like and dedifferentiated carcinoma as EC variants in the fifth edition of the WHO Classification of Female Genital Tumours, and recognition that carcinosarcoma is a biphasic carcinoma rather than a sarcoma. Each EC variant has distinct molecular abnormalities, including TCGA-based molecular subtypes, allowing further subclassification and adding complexity. In contrast to this rapid progress in understanding EC, there are only two recognized EC precursor lesions: endometrial atypical hyperplasia/endometrioid intraepithelial neoplasia (EAH/EIN) and serous intraepithelial carcinoma, a situation that has not changed for many years. Diagnosis of EC precursors is a cornerstone of surgical pathology practice, with early diagnosis contributing to the relatively favorable prognosis of EC. In this review we relate the precursor lesions to each of the EC morphological variants and molecular subtypes, discuss how successful early diagnosis is for each variant/molecular subtype and how it might be improved, and identify knowledge gaps where there is insufficient understanding of EC histogenesis. © 2020 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

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.

Whole-proteome analysis of mesonephric-derived cancers describes new potential biomarkers

Mesonephric carcinomas (MEs) and female adnexal tumors of probable Wolffian origin (FATWO) are derived from embryologic remnants of Wolffian/mesonephric ducts. Mesonephric-like carcinomas (MLCs) show identical morphology to ME of the cervix but occur in the uterus and ovary without convincing mesonephric remnants. ME, MLC, and FATWO are challenging to diagnose due to their morphologic similarities to Müllerian/paramesonephric tumors, contributing to a lack of evidence-based and tumor-specific treatments. We performed whole-proteomic analysis on 9 ME/MLC and 56 endometrial carcinomas (ECs) to identify potential diagnostic biomarkers. Although there were no convincing differences between ME and MLC, 543 proteins showed increased expression in ME/MLC relative to EC. From these proteins, euchromatic histone lysine methyltransferase 2 (EHMT2), glutathione S-transferase Mu 3 (GSTM3), eukaryotic translation elongation factor 1 alpha 2 (EEF1A2), and glycogen synthase kinase 3 beta were identified as putative biomarkers. Immunohistochemistry was performed on these candidates and GATA3 in 14 ME/MLC, 8 FATWO, 155 EC, and normal tissues. Of the candidates, only GATA3 and EHMT2 were highly expressed in mesonephric remnants and mesonephric-derived male tissues. GATA3 had the highest sensitivity and specificity for ME/MLC versus EC (93% and 99%) but was absent in FATWO. EHMT2 was 100% sensitive for ME/MLC & FATWO but was not specific (65%). Similarly, EEF1A2 was reasonably sensitive to ME/MLC (92%) and FATWO (88%) but was the least specific (38%). GSTM3 performed intermediately (sensitivity for ME/MLC and FATWO: 83% and 38%, respectively; specificity 67%). Although GATA3 remained the best diagnostic biomarker for ME/MLC, we have identified EHMT2, EEF1A2, and GSTM3 as proteins of interest in these cancers. FATWO's cell of origin is uncertain and remains an area for future research.

18F-FDG Uptake in a Mesonephric Carcinoma

We present the case of a 39-year-old woman with vaginal bleeding and abdominal pain. An F-FDG PET/CT showed high F-FDG uptake in a tumor in the pouch of Douglas, in 3 lymph nodes in the pelvis, and in the left tuber ischiadicum. Biopsies revealed a mesonephric carcinoma with metastases. Six series of empiric chemotherapy with carboplatin, paclitaxel, and bevacizumab were not sufficient to treat the cancer, and checkpoint immunotherapy with nivolumab and ipilimumab was initialized.

Molecular profiling of mesonephric and mesonephric-like carcinomas of cervical, endometrial and ovarian origin

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KRAS mutation is a major driver in mesonephric and mesonephric-like carcinomas of cervical, endometrial or ovarian origin.

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ARID1A and PIK3CA mutations were also identified in endometrial and ovarian mesonephric-like carcinomas.

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Peripheral blood ctDNA liquid biopsy may detect mutations in recurrent and/or metastatic mesonephric carcinomas.

Mesonephric carcinoma is a rare cancer that most often arises within the cervix, and less frequently, in the ovary and endometrium. A retrospective search of our CLIA-certified and CAP-accredited reference molecular laboratory database (Foundation Medicine, Inc.) identified 20 mesonephric or mesonephric-like, cervical (n = 10), endometrial (n = 5), ovarian (n = 4) or peri-bladder (n = 1) carcinomas that had undergone comprehensive genomic profiling via next generation sequencing. Activating KRAS mutations were present in 90%, 18 of 20 cases, including G12V (n = 7), G12D (n = 6), G12A (n = 3) and G12C (n = 2). Other recurrent alterations were identified in ARID1A (25%), PIK3CA (20%), CTNNB1 (15%), TP53 (10%), MLL2 (10%) and CDKN2A (10%). One KRAS wild-type case had a GATA3 mutation as the sole alteration, while the second KRAS wild-type case had an EGFR exon 20 insertion D770_N771insSVD alteration. All tumors were negative for HPV DNA, microsatellite instability, high tumor mutational burden and homologous recombination deficiency. A circulating tumor DNA (ctDNA) liquid biopsy from peripheral blood, which was performed 6 years after original solid tumor resection in one patient with suspected lung metastasis, revealed concordance of KRAS alteration, gains of chromosomes 1q, 2, 10, 12 and 20, plus new TP53 alterations in the liquid biopsy compared to the original sample. KRAS G12 mutation is major driver of mesonephric and mesonephric-like carcinomas, with less frequent contribution by ARID1A and PIK3CA pathways in tumors of non-cervical origin. ctDNA liquid biopsy may be useful in detecting mutations in recurrent or metastatic patients, who may potentially be eligible for trials against emerging targeted therapies.

Mesonephric Adenocarcinoma of the Uterine Fundus Exhibiting High 18F-FDG Uptake

Mesonephric adenocarcinoma is a rare tumor that is considered to develop from mesonephric remnants of the female genital tract. This tumor usually occurs in the lateral wall of the uterine cervix. Herein, we present an exceptionally rare case of mesonephric adenocarcinoma located in the uterine fundus. The tumor exhibited intense hypermetabolism on ¹⁸F-FDG PET/CT. Based on the characteristic histologic features and immunohistochemical phenotypes, the diagnosis of mesonephric adenocarcinoma was confirmed. The patient underwent hysterectomy with bilateral salpingo-oophorectomy and pelvic lymph node dissection, and no lymph node or distant metastasis was identified. After 20 months of surveillance without adjuvant therapy, she remains free of relapse.

Ovarian mesonephric-like adenocarcinoma arising in serous borderline tumor: a case report with complex morphological and molecular analysis

BACKGROUND

Mesonephric-like adenocarcinoma (M-LAC) is a rare, recently described tumor occurring in the uterine corpus and ovary, which shares the same morphological and immunohistochemical features with the more common mesonephric adenocarcinoma (MAC), which mostly arises the uterine cervix. Despite the similarities between these tumors, the histogenesis of M-LAC is still disputable.

CASE PRESENTATION

Sixty-one-year-old woman presented with an advanced tumor of the left ovary with intraabdominal spread and liver metastases. After receiving 5 cycles of neoadjuvant chemotherapy, she underwent a hysterectomy with bilateral salpingo-oophorectomy, and resection of the liver metastasis, omentum, and appendix. Histologically, the ovarian tumor consisted of two components, whose morphology and immunohistochemical results were typical of either a serous borderline tumor (immunohistochemical positivity for PAX8, WT1, ER and PR) or a mesonephric-like carcinoma (immunohistochemical positivity for PAX8, TTF1 and GATA3). Only the component of the mesonephric-like adenocarcinoma metastasized to the omentum and liver. A molecular analysis with a panel of 271 genes (size 1020 kbp) was performed separately on samples from the borderline tumor, primary ovarian mesonephric-like adenocarcinoma, and liver metastasis. The results showed the clonal origin of all samples, which shared the same KRAS (NM_004985.3:c.34G > T, p.(G12C)) and PIK3CA (NM_006218.2:c.1633G > A, p.(E545K)) somatic mutations. Moreover, in the sample from the primary mesonephric-like carcinoma and its liver metastasis a likely pathogenic somatic MYCN mutation (NM_005378.4:c.131C > T, p.(P44L) was found. In all samples, the deletion of exons 9-10 in the CHEK2 gene was present, which is in concordance with the previously performed genetic testing of the blood specimen which revealed the hereditary CHEK2 mutation in this patient.

CONCLUSIONS

Our result support the theory that at least some mesonephric-like ovarian adenocarcinomas are of Müllerian origin. The serous borderline tumor seems to be a precursor of mesonephric-like adenocarcinoma, which has been proven in our case by both tumors sharing the same mutations, and the presence of cumulative molecular aberrations in the mesonephric-like adenocarcinoma.