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

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.

Primary mesonephric adenocarcinoma of the fallopian tube: A case report

BACKGROUND

Mesonephric adenocarcinoma (MNAC) is an extremely rare malignancy in the female genital tract. Only a few cases have been reported in the literature, and most of them occurred in the cervix, with extremely rare cases in the uterine body and ovary. MNAC has never been reported to arise in the fallopian tube.

CASE SUMMARY

A 45-year-old woman was referred to our institution with a history of abdominal pain. Ultrasound revealed a cystic and solid mass in left adnexal region. The patient underwent complete staging surgery when intraoperative pathological examination demonstrated that the mass was malignant. The final histological and immunohistochemical results confirmed the diagnosis of MNAC originating from the fallopian tube. Then she received four cycles of combination chemotherapy with carboplatin plus paclitaxel. The tumor recurred with hepatic metastases 4 mo after initial surgery, and second resection of the tumors in the liver plus partial hepatectomy was performed. She was supplemented with five courses of a new combination chemotherapy with gemcitabine plus carboplatin, and there was no evidence of recurrence within the 22-mo follow-up period after the second surgery.

CONCLUSION

MNAC originating from the fallopian tube is an extremely rare and high malignancy with a poor prognosis. It can be very aggressive, even at early stage. Little is known about the clinical characteristics, pathological diagnosis, prognosis, and optimal management strategy of MNAC originating from the fallopian tube. Herein we report the first case of primary MNAC deriving from the fallopian tube.

Targeted Genomic Sequencing Reveals Different Evolutionary Patterns Between Locally and Distally Recurrent Glioblastomas

BACKGROUND/AIM

Glioblastoma is the most malignant form of astrocytoma. The purpose of this study was to analyze the genetic characteristics of primary and recurrent glioblastomas using targeted sequencing and investigate the differences in mutational profiles between the locations of tumor recurrence.

MATERIALS AND METHODS

Fourteen glioblastoma patients who developed local (n=10) or distal (n=4) recurrence were included in the study. Targeted sequencing analysis was performed using the primary (n=14) and corresponding recurrent (n=14) tumor tissue samples.

RESULTS

The local and distal recurrence groups showed different genetic evolutionary patterns. Most of the locally recurrent glioblastomas demonstrated concordant mutational profiles between the primary and recurrent tumors, suggesting a linear evolution. In contrast, all cases of distally recurrent glioblastomas showed changes in mutational profiles with newly acquired mutations when compared to the corresponding primary tumors, suggesting a branching evolution.

CONCLUSION

Locally and distally recurrent glioblastomas exhibit different evolutionary patterns.

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.

Clinicopathological Characteristics of Squamous Cell Carcinoma and High-grade Squamous Intraepithelial Lesions Involving Endocervical Polyps

BACKGROUND/AIM

To investigate the clinicopathological characteristics of high-grade squamous intraepithelial lesions (HSILs) and squamous cell carcinomas (SCCs) involving endocervical polyps (ECPs).

PATIENTS AND METHODS

We collected the endocervical polypectomy cases and performed pathological examination and cytohistological correlation.

RESULTS

During a period of 12 years, 21 (1.1%) HSILs and two (0.1%) SCCs involving ECPs were identified in 1,905 cases. Twelve (63.1%) of the 19 cases were cytohistologically concordant. In five HSILs and one SCC with polypectomy margin involvement, residual HSIL was identified in conization or hysterectomy specimens. Furthermore, in two HSIL patients and one SCC patient with negative polypectomy margins, residual HSILs were found in the conization specimens.

CONCLUSION

The prevalence of HSIL and SCC involving ECP in our cohort was similar to the rates found in previous studies. The presence of residual HSIL in nonpolypoid cervical tissue regardless of the polypectomy margin involvement suggests that conization or hysterectomy is needed for diagnostic or treatment purposes.

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.

Clinicopathological and Molecular Differences Between Gastric-type Mucinous Carcinoma and Usual-type Endocervical Adenocarcinoma of the Uterine Cervix

BACKGROUND/AIM

We investigated differences in the clinicopathological and molecular characteristics between gastric-type mucinous carcinoma (GMC) and usual-type endocervical adenocarcinoma (UEA).

PATIENTS AND METHODS

We collected the clinicopathological information and performed targeted genomic sequencing analysis.

RESULTS

GMCs exhibited significantly deeper invasion depth, larger horizontal spread, more advanced stage, more frequent distant metastasis, and more frequent parametrial and vaginal extension. Disease-free survival time of GMC patients was significantly shorter than that of UEA patients. GMCs displayed mutant p53 immunostaining pattern, whereas UEAs exhibited p16 block positivity. GMCs harbored mutations in KRAS, TP53, NF1, CDKN2A, STK11, and ARID1A. One GMC exhibited MDM2 amplification. In contrast, UEAs harbored mutations in HRAS, PIK3CA, and BRCA2. Two UEAs were found to have novel TP53 mutations.

CONCLUSION

GMC is associated with more aggressive behavior than UEA. Distinctive p53 and p16 immunostaining patterns enable differential diagnosis. GMC and UEA exhibit genetic heterogeneity with potentially actionable molecular alterations.

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.

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.

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.

Clinicopathological Characteristics of Pleomorphic High-Grade Squamous Intraepithelial Lesion of the Uterine Cervix: A Single-Institutional Series of 31 Cases

We investigated the clinicopathological characteristics of 31 cases of pleomorphic high-grade squamous intraepithelial lesions (PHSIL) of the uterine cervix. We reviewed electronic medical records and all available slides to collect clinical and pathological information. PHSILs were histologically characterized by significant nuclear enlargement, marked pleomorphism, hyperchromasia, increased mitotic activity, and frequent atypical mitoses. In the majority of cases (24/31; 77.4%), this striking nuclear atypia involved both the surface epithelium and the endocervical glands. In the remaining seven cases, pleomorphic cells were observed in the surface epithelium only. PHSILs involving both the surface epithelium and glands showed higher mitotic counts and Ki-67 labelling indices than the surface-only PHSILs. Invasive squamous cell carcinoma was present in only one case (3.2%), and none developed recurrent disease. Our observations of striking nuclear atypia in cases of HSIL did not indicate increased aggressiveness. Further investigations are required for confirmation of our data in larger cohorts.

Endometriosis-related pathology: a discussion of selected uncommon benign, premalignant and malignant lesions

Endometriosis is an extremely common condition and, in most cases, establishing a histological diagnosis is straightforward, although a variety of benign alterations may result in problems with interpretation. In this review, I discuss selected uncommon variants of endometriosis or benign alterations that may result in diagnostic problems. The topics covered include the contentious issue of so-called atypical endometriosis, stromal endometriosis, polypoid endometriosis, and the association of endometriosis with florid mesothelial hyperplasia. The propensity of endometriosis to undergo neoplastic transformation (especially to endometrioid and clear cell carcinoma) is well known. Selected issues relating to the various neoplasms that can arise in endometriosis are discussed, with a particular concentration on unusual variants of endometrioid carcinoma that result in a disproportionately high number of issues in referral practice. The propensity of ovarian endometrioid carcinomas to show an unexpected ('aberrant') immunophenotype with positive staining with 'intestinal' markers and negative staining with Mullerian markers is also discussed. Uncommon tumour types that may arise in endometriosis, namely seromucinous neoplasms, mesonephric-like carcinomas, and somatically derived yolk sac tumours, are also covered.

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.

Ovarian Combined Low-grade Serous and Mesonephric-like Adenocarcinoma: Further Evidence for A Mullerian Origin of Mesonephric-like Adenocarcinoma

Mesonephric-like adenocarcinomas are rare neoplasms occurring in the uterine corpus and ovary which bear a close morphologic resemblance to cervical mesonephric adenocarcinomas. They also have a similar immunophenotype and harbor similar molecular abnormalities to mesonephric adenocarcinomas and it is debated whether they are truly of mesonephric origin or represent Mullerian neoplasms closely mimicking mesonephric adenocarcinomas. We report an unusual case with bilateral ovarian serous borderline tumors and extraovarian low-grade serous carcinoma (invasive implants). In one ovary, there was a component of mesonephric-like adenocarcinoma. The immunophenotypes of the serous and the mesonephric-like components were distinct and as expected for the individual tumor types (serous component diffusely positive with WT1 and estrogen receptor and negative with GATA3, TTF1 and CD10; mesonephric-like component WT1 and estrogen receptor negative and GATA3, TTF1, and CD10 positive; both components diffusely positive with PAX8 and exhibiting "wild-type" p53 immunoreactivity). In all components (bilateral serous borderline tumors, low-grade serous carcinoma and mesonephric-like adenocarcinoma), an identical KRAS mutation was detected (NM_004985.4): c.35G>A, p.(G12D) proving a clonal association between the serous and mesonephric-like components and excluding a collision neoplasm. This represents the second reported case of a combined ovarian low-grade serous tumor and mesonephric-like adenocarcinoma; in the previously reported case, an identical NRAS mutation was present in both components. These 2 cases provide evidence that ovarian mesonephric-like adenocarcinomas have, at least in some cases, a Mullerian origin and differentiate along mesonephric lines. We present additional evidence for this by reviewing associated findings in published and unpublished ovarian mesonephric-like adenocarcinomas; 8 of 11 of these neoplasms contained other Mullerian lesions in the same ovary, mainly endometriosis and adenomas/adenofibromas.

Mesonephric-like adenocarcinomas of the uterine corpus: report of a case series and review of the literature indicating poor prognosis for this subtype of endometrial adenocarcinoma

PURPOSE

Endometrial mesonephric-like adenocarcinoma (ML-AC) represents a recently recognized subtype of endometrial adenocarcinoma (AC) associated with a subtle immunophenotype with a characteristic KRAS-mutation. Detailed clinico-pathologic analyses and prognostic data on ML-AC are limited.

METHODS

We report a series of four cases with histopathological, immunohistochemical, and molecular analyses. These cases as well as the data of previously published cases were reviewed for clinico-pathologic variables and clinical follow-up information.

RESULTS

Forty cases of ML-AC were identified. ML-AC represents about 1% of all endometrial carcinomas. Similar to other types of endometrial AC, vaginal bleeding was the leading presenting symptom, and the mean age was 60.0 years (range 31-91). More than a half of the patients presented with locally advanced disease (≥ FIGO stage II) at time of diagnosis, developed a recurrence or died of the disease within a mean follow-up period of 24.7 months (range 3-144.5 months). The most common site of distant disease was pulmonary involvement. Microscopically, ML-ACs present with mixed morphology and show a co-expression of so-called mesonephric and Müllerian markers, suggesting a Müllerian origin of the tumors. Immunostaining for PD-L1 was negative in all tested cases, using different antibodies against PD-L1. Retained staining for mismatch repair proteins on immunohistochemistry and a POLE-mutation suggest a copy number low phenotype within the molecular classification of endometrial carcinomas. Almost all cases showed a KRAS-mutation at codon 12 (mostly G12V).

CONCLUSION

Uterine ML-AC represents a distinct subtype of invasive endometrial AC, associated with KRAS-mutations and characteristic immunohistochemical findings. Clinically, ML-AC may show an aggressive behavior with a high rate of recurrent disease and a substantial risk for distant metastatic disease, especially to the lungs.

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

Endometrial mesonephric-like carcinomas (MLCa) are uncommon with <50 reported cases thus far. Previous studies have characterized the histologic, immunohistochemical, and molecular features of MLCa; however, there is limited information with respect to outcome. This single-institution study of 23 uterine MLCas characterizes the behavior of such a neoplasm. Uterine MLCas (2004-present) had review of histologic features, immunohistochemical results, molecular profile, and clinical information (stage, treatment, follow-up). The behavior of MLCa was compared with low-grade endometrioid carcinomas (ECas) and uterine serous carcinomas (USCs) treated at our institution from 2004 to present. All MLCas had a mixture of previously described architectural and cytologic features most notably ductal and/or tubular architecture (21/23), nuclei resembling those of papillary thyroid carcinoma (18/23), and at least focal intraluminal eosinophilic secretions (20/23). Immunoperoxidase studies facilitated diagnosis in 22 cases: CD10, 10/10; calretinin, 5/15; estrogen receptor (≥10% nuclei), 6/21; progesterone receptor, 1/15; GATA-3, 15/16; TTF-1, 11/16. Fourteen of 17 tested cases had a KRAS mutation (7 as the only alteration; 7 with additional mutations including PIK [n=5]; PTEN [n=2], CTNNB1 [n=1]).One case had mutations in PTEN, PIK, and CTNNB1 without KRAS; 2 cases had no detectable somatic mutation. Overall, 48% of patients presented with International Federation of Gynecology and Obstetrics (FIGO) stage 3 or 4 disease with the following uterine risk factors: >50% myometrial invasion, 20/23; lymphovascular space invasion, 16/23; cervical stromal invasion, 7/23. Twenty patients had adjuvant therapy (7 radiation only; 13 chemotherapy±radiation), whereas 3 patients had either unknown or declined therapy. Follow-up was known for 21 patients: 17 patients had recurrences or never achieved remission with the lung being the most common recurrence site (n=9); 7 patients died of disease. The median progression-free survival was 18.2 months for MLCa compared with 183 months for ECa and 67.1 months for USC. The median overall survival for MLCa was 70.6 months compared with 139.1 months for USC (median survival for ECa not reached). Uterine MLCa is uncommon with most tumors recognized by architectural heterogeneity, vesicular, overlapping nuclei with grooves, and eosinophilic luminal secretions. The typical immunoprofile includes low to absent expression of hormone receptors but at least focal expression of GATA-3 and/or TTF-1. Most tested cases had a KRAS mutation although genetic mutations typically associated with ECa are not uncommon. Compared with more commonly encountered types of ECa, MLCa is more aggressive with a tendency towards earlier and distant recurrence.

Targeted Genomic Profiling of Female Adnexal Tumors of Probable Wolffian Origin (FATWO)

Female adnexal tumor of probable Wolffian origin (FATWO) is a rare gynecologic neoplasm of low-malignant potential presumed to be derived from mesonephric remnants in the upper female genital tract. Similarly, mesonephric remnants in the lower female genital tract are thought to be the origin for mesonephric carcinoma. Although the molecular alterations in mesonephric carcinoma have been recently reported, the pathogenesis of and molecular alterations in FATWO are not well understood. The aims of this study were to examine the molecular alterations in FATWO and to establish whether these neoplasms are molecularly similar to mesonephric carcinoma. Eight FATWOs underwent massively parallel sequencing to detect single nucleotide variations, copy number variations, and structural variants by surveying exonic DNA sequences of 300 cancer genes and 113 introns across 35 genes. Good quality DNA was isolated from 7 of 8 cases. Novel KMT2D variants (1 frameshift, 3 missense) were identified in 4 of 7 cases (57%), but were variants of uncertain biologic significance. STK11 mutations (both frameshift) were identified in 2 of 7 cases (29%); one of these was in a patient with a known history of Peutz-Jeghers syndrome. A mutation in the chromatin remodeling gene ARID1B was identified in 1 of 7 cases (14%). No cases harbored KRAS, NRAS, TP53, PIK3CA, PTEN, or DICER1 mutations. There were relatively low numbers of copy number variations, and no recurrent copy number variations were identified. One case demonstrated moderate copy gain of CCND1. No structural variants were identified. In summary, FATWO is characterized molecularly by the absence of KRAS/NRAS mutations (characteristic of mesonephric carcinoma), absence of DICER1 mutations (characteristic of Sertoli-Leydig cell tumor) and frequent KMT2D mutations of unknown biologic significance. FATWOs exhibit a limited number of molecular aberrations that are significantly different from those reported in tumors in the differential diagnosis, and our results question the relationship of mesonephric carcinoma with FATWO. Disease-defining molecular alterations for FATWO have yet to be discovered.

Endometrium-Limited Metastasis of Extragenital Malignancies: A Challenge in the Diagnosis of Endometrial Curettage Specimens

Malignancies of extragenital origin very rarely metastasize to the uterine body. Endometrium-limited metastases may pose diagnostic challenges in endometrial curettage specimens as they may be misdiagnosed as primary endometrial tumors. We investigated the clinicopathological characteristics of seven cases with endometrial-limited metastases from carcinomas of the nasopharynx (n = 1), breast (n = 2), colon (n = 2), stomach (n = 1), and appendix (n = 1). The patients' ages ranged from 36 to 71 (mean: 55.4) years. None of the patients had a remarkable gynecological history, and the presenting sign in all cases was abnormal uterine bleeding. Although myometrial involvement was absent, multiple metastases were already present in extrauterine locations such as the lung, liver, bone, abdominopelvic peritoneum, and omentum. All patients underwent ultrasonographic examination prior to endometrial curettage. The histologies of the endometrial metastases identified from the curettage specimens were identical to those of the corresponding primary tumors. Ancillary tests including immunostaining and Epstein-Barr virus-encoded RNA in situ hybridization confirmed the extragenital origin. Endometrium-limited metastases from extragenital malignancies are extremely rare. They present with abnormal vaginal bleeding and mimic endometrial carcinomas of endometrioid or poorly differentiated types. Since their clinical presentations and histological features are similar to those of primary endometrial tumors, pathologists should consider the possibility of metastases while evaluating endometrial curettage specimens obtained from patients with a history of extragenital malignancies.

Targeted Sequencing of Tubo-ovarian and Peritoneal High-grade Serous Carcinoma With Wild-type p53 Immunostaining Pattern

BACKGROUND/AIM

We aimed to demonstrate the use of next-generation sequencing (NGS) to confirm the presence of tumor protein 53 (TP53) mutations in tubo-ovarian and peritoneal high-grade serous carcinoma (HGSC) with a wild-type p53 immunostaining pattern and investigate whether the TP53 mutational status is altered by chemotherapy.

MATERIALS AND METHODS

A commercial NGS panel comprising 171 genes was used to analyze the genetic profiles of 15 HGSC samples. Paired specimens obtained before and after chemotherapy were available for four patients.

RESULTS

All examined samples exhibited TP53 mutations. For all the patients who underwent neoadjuvant or postoperative adjuvant chemotherapy, TP53 mutations identified in samples obtained after chemotherapy were the same as those detected in pre-chemotherapeutic samples.

CONCLUSION

HGSCs exhibit TP53 mutations even though a subset of HGSCs displayed a wild-type p53 immunostaining pattern. Chemotherapy does not affect the TP53 mutational status in HGSC.

Uterine lesions with sex cord-like architectures: a systematic review

Background

Sex cord-like elements are rarely observed in uterine lesions, but these morphological patterns could appear in a variety of uterine tumors and non-tumorous lesions. In this review, we collected the literatures regarding the uterine tumorous and non-tumorous lesions containing sex cord-like elements and summarized these lesions in terms of clinicopathological, immunohistochemical, and molecular features in order to further understand these lesions and provide some new ideas for differential diagnosis.

Main body

This section provides a comprehensive overview of the clinicopathological, immunohistochemical, and molecular features of uterine lesions with sex cord-like architectures including uterine tumors resembling ovarian sex cord tumors, endometrial stromal tumors, adenomyosis, endometrial polyps, leiomyoma, epithelioid leiomyosarcoma, adenosarcoma, sertoliform endometrioid carcinoma, corded and hyalinized endometrioid carcinoma, mesonephric adenocarcinoma, and mesonephric-like adenocarcinoma. The differential diagnosis based on morphology, immunohistochemistry, and molecular alterations has also been discussed.

Conclusion

The sex cord-like areas in these lesions show heterogeneous but similar morphological features. Additionally, immunohistochemical staining plays a limited role in differential diagnosis. Furthermore, it is of significance for pathologists to better understand these lesions in order to avoid confusion and mistakes during pathological diagnosis, especially in a biopsy/curettage specimen.

Mesonephric Adenocarcinoma of the Uterine Corpus: Report of 2 Cases and Review of the Literature

Mesonephric adenocarcinoma (MNA) is believed to arise from benign mesonephric remnants or hyperplasia located in the lateral walls of the uterine cervix. They are uncommon in other sites of the gynecologic tract, and exceptionally rare in the uterine corpus. So far, only 30 cases of uterine MNA have been reported in the literature, as a result, the etiology, clinical behavior, choice of treatment, and histogenesis of uterine MNA are still unclear. In this study, we report 2 cases of MNA of uterine corpus. One case involved the inner half of myometrium with endometrial involvement; the second case involved the outer half of myometrium without endometrial involvement. We also reviewed the clinical and pathologic presentations of this rare entity, and discussed the histogenesis of uterine corpus MNA based on recent molecular findings.

Cytologic features of upper gynecologic tract adenocarcinomas exhibiting mesonephric-like differentiation

BACKGROUND

Mesonephric adenocarcinomas are rare neoplasms which most commonly arise in the lateral cervix and vagina. Tumors with similar morphologic, immunophenotypic, and molecular characteristics recently have been described in the uterine corpus and ovary. Herein, the authors sought to characterize the cytomorphologic features of adenocarcinomas exhibiting mesonephric-like differentiation arising in the upper gynecologic tract.

METHODS

Institutional databases were queried retrospectively for tumors of the upper gynecologic tract described as a "tumor of Wolffian origin" or "with mesonephric features" between 2007 and 2017. All available cytologic material was reviewed. Cytomorphologic characteristics were evaluated by 3 pathologists.

RESULTS

The current study cohort consisted of 8 cases taken from 7 patients. Primary sites included the ovary (3 cases); endometrium (4 cases); and pelvis, not otherwise specified (1 case). All cases demonstrated tight 3-dimensional clusters of overlapping cells. Additional architectural features included tubular (5 of 8 cases; 63%) and papillary (3 of 8 cases; 38%) formations. Cells were small with scant (7 of 8 cases; 88%) to moderate (1 of 8 cases; 12%) cytoplasm. Three of the 8 cases (38%) demonstrated extracellular hyaline globules. Nuclei were uniform in size (6 of 8 cases; 75%) or showed mild anisonucleosis (2 of 8 cases; 25%). Nuclear grooves and indentations were observed in all cases. Mitoses (5 of 8 cases; 63%) and apoptotic bodies (4 of 8 cases; 50%), when present, were rare. No necrosis was noted.

CONCLUSIONS

Adenocarcinomas exhibiting mesonephric-like differentiation show a monotonous population of small cells with scant to moderate cytoplasm and abundant nuclear grooves arranged in tight, overlapping, 3-dimensional clusters. Occasionally, papillary or tubular architecture, as well as extracellular hyaline globules, may be seen. These features should prompt further testing (eg, immunohistochemistry) to confirm the diagnosis and to exclude potential mimics.

Mesonephric adenocarcinoma of the cervix: a case report with a three-year follow-up, lung metastases, and next-generation sequencing analysis

Background

Mesonephric adenocarcinoma (MNAC) is a rare tumor of the female genital tract, which originates from mesonephric duct remnants. Its diagnosis is pathologically challenging, because MNAC may exhibit a mixture of morphological patterns that complicates the differential diagnosis.

Case presentation

The patient in this case was a 48-year-old woman with a polypoid mass protruding into the endocervical canal. The patient underwent a total hysterectomy outside the institution. During biopsy, the mass showed a cerebroid aspect. Histological study revealed a tumor with a predominantly tubular and ductal growth pattern. The immunoprofile showed negative staining for calretinin, carcinoembryonic antigen (CEAm), estrogen receptors (ER), and progesterone receptors (PR), and positive staining for CD10, p16, and PAX2. The Ki-67 score was 46%. Using a next-generation sequencing assay, we documented genomic alterations in KRAS and CTNNB1, low tumor mutation burden (TMB), and an absence of microsatellite instability. In addition, gain of the long arm of chromosome 1 (1q) was also documented using chomogenic in situ hybridization (CISH). Three years later, the patient presented pulmonary nodules in the lingula and left basal lobe that were resected by thoracotomy. The histopathologic study of the pulmonary nodules confirmed the presence of metastases.

Conclusion

Carcinomas of mesonephric origin are among the rarest subtypes of cervical tumors. We report the first case of mesonephric adenocarcinoma of the cervix with lung metastases showing a CTNNB1 gene mutation.

Coexistence of endometrial mesonephric-like adenocarcinoma and endometrioid carcinoma suggests a Müllerian duct lineage: a case report

Background

Endometrial mesonephric-like adenocarcinomas exhibit classical histologic features of mesonephric carcinoma; however, it remains unclear whether these tumors represent mesonephric (Wolffian) carcinoma or endometrioid (Müllerian) carcinomas that closely mimic mesonephric carcinoma.

Case presentation

A 32-year-old Japanese primigravida presented with atypical vaginal bleeding. An endometrial biopsy suggested low-grade endometrioid carcinoma, and she was administered medroxyprogesterone acetate. Her tumor recurred 6 years later, and she underwent hysterectomy, salpingo-oophorectomy, and omentectomy, at which point she was diagnosed with mesonephric-like adenocarcinoma of the uterine endometrium. Retrospective pathological review of the initial biopsy confirmed coexisting low-grade endometrioid carcinoma and mesonephric-like adenocarcinoma of the uterine endometrium. On immunohistochemistry, the endometrioid carcinoma component was diffuse positive for estrogen and progesterone receptors but negative for thyroid transcription factor 1. However, the mesonephric-like adenocarcinoma component exhibited a mixture of estrogen receptor- and thyroid transcription factor 1-positive cells within the same glands.

Conclusions

We encountered a patient with coexisting endometrial mesonephric-like adenocarcinoma and low-grade endometrioid carcinoma, which was treated using medroxyprogesterone acetate therapy, resulting in recurrence of mesonephric-like adenocarcinoma alone. These clinicopathological findings support the prevailing notions that mesonephric-like adenocarcinoma is a Müllerian adenocarcinoma exhibiting mesonephric differentiation.

Clinicopathological Characteristics of Well-differentiated Papillary Mesothelioma of The Peritoneum: A Single-institutional Experience of 12 Cases

BACKGROUND/AIM

Well-differentiated papillary mesothelioma (WDPM) is histologically characterized by papillary architecture with fibrovascular cores, lined by bland mesothelial cells. We recently experienced a case of WDPM associated with multiple peritoneal inclusion cysts, which prompted us to initiate a comprehensive review of previously diagnosed WDPM cases.

MATERIALS AND METHODS

The clinicopathological characteristics and immunophenotype of 12 cases of peritoneal WDPM were investigated using a review of electronic medical records, pathological examination, and immunostaining.

RESULTS

The patients' ages ranged from 23 to 75 years. No patient had endometriosis or a previous history of asbestos exposure. Ten tumors were detected incidentally during surgery for other causes. Most tumors appeared as a small, single nodule on the peritoneal surface, but in three cases, WDPM presented as multiple lesions. All but one patient had no symptoms. All the patients examined are still well without postoperative recurrence. Histologically, all cases demonstrated typical papillary architecture with fibrovascular cores. The mesothelial cells lining the papillae consisted mostly of single row of cells, although areas of proliferation to multiple layers were observed in a few cases. Their nuclei appeared bland, but two cases exhibited mild nuclear atypia and prominent nucleoli. Immunostaining revealed that the mesothelial cells were positive for D2-40, cytokeratin 5/6, cytokeratin 7, and Wilms' tumor 1.

CONCLUSION

We herein demonstrated the clinicopathological characteristics of peritoneal WDPMs. WDPM has distinct pathological features. Although all cases we examined were uneventful after surgery, further surveillance is recommended since the biological behavior of WDPM is still uncertain.