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.

Diagnostic Value of Immunostaining for Thyroid Transcription Factor 1 (TTF1) and Paired Box 8 (PAX8) in Distinguishing Pulmonary Metastases of Mesonephric and Mesonephric-like Adenocarcinomas from Primary Lung Adenocarcinomas

BACKGROUND/AIM

Both mesonephric adenocarcinoma (MA) and mesonephric-like adenocarcinoma (MLA) express thyroid transcription factor 1 (TTF1). TTF1 is also considered a highly sensitive and specific diagnostic marker for primary lung adenocarcinoma (PLA). However, distinguishing PLA from pulmonary metastatic MA/MLA (PMM) based on the expression of TTF1 alone can be difficult. This study aimed to investigate the expression of TTF1 and paired box 8 (PAX8) and assess their value in distinguishing PMM from PLA.

PATIENTS AND METHODS

We reviewed the electronic medical records and pathology slides of eight PMM cases. We conducted immunostaining for TTF1 and PAX8 in 6, 8, and 21 cases of primary MA/MLA, PMM, and PLA, respectively.

RESULTS

Two patients with stage IB uterine MLA developed lung metastases at 5 and 57 months after hysterectomy. Solitary pulmonary nodules were suspected to be primary lung cancer in two patients. Compared to primary tumors, all matched PMMs exhibited reduced TTF1 immunoreactivity. In contrast, the majority of PLAs showed uniform and intense TTF1 expression. All except one PMM exhibited diffuse and strong PAX8 expression, while only one PLA showed focal and weak PAX8 expression.

CONCLUSION

Immunostaining for TTF1 and PAX8 can help in distinguishing PMM from PLA in the diagnosis of pulmonary lesions detected in patients with a history of MA/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.

Case Report: The first report of PPP2R1A mutations in mesonephric-like adenocarcinoma of endometrial carcinoma

We performed clinical treatment, histopathology, immunohistochemistry and molecular analyses. To compare with the published literature and have a reference overview. A 57-year-old woman and a 77-year-old woman presented with mesonephric-like adenocarcinoma of endometrium at an early clinical stage. The former had no deep myometrial infiltration and no regional lymph node involvement. The latter had deep myometrial infiltration, presence of LVSI and no regional lymph node involvement. Both of the tumor cells were positive for PAX8, GATA-3,CD-10,TTF-1,AE1/AEs,Ki67,P53 and P16 in immunohistochemical staining (IHC)Test. Primary tumors were examined for gene mutations by next generation sequencing. The former was identified KRAS mutation. The latter had KRAS,PIKCA and PPP2R1A mutations. To our knowledge, it is the first time that PPP2R1A(protein phosphatase 2,regulatory subunit A,α) mutation in MLA is reported in English literature.

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

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

Endocervical Adenocarcinoma Showing Microcystic, Elongated, and Fragmented (MELF) Pattern of Stromal Invasion: A Single-Institutional Analysis of 10 Cases with Comprehensive Clinicopathological Analyses and Ki-67 Immunostaining

Microcystic, elongated, and fragmented (MELF) pattern of invasion has seldom been documented in endocervical adenocarcinoma (EAC). The aim of this study was to analyze the clinicopathological characteristics of EAC showing MELF pattern. We collected the clinicopathological information of 10 cases of EAC with the MELF pattern and conducted polymer-based immunostaining for Ki-67 (dilution 1:200, clone MIB-1) on these cases. Ki-67 expression was assessed using the average estimation within the hotspot method. All tumors were human papillomavirus-associated EAC with Silva pattern C. All except one tumor exceeded 3 cm in size. Five tumors involved the entire thickness of the cervical stroma, and four tumors extended into the parametrium. Lymphovascular space invasion was identified in six cases. Two patients developed metastatic recurrences in the para-aortic lymph nodes and lungs, respectively. The MELF area showed significantly lower Ki-67 labelling index than that of a conventional tumor area. We confirmed our previous observation that the MELF area displayed lower proliferative activity than the conventional tumor area of EAC. We also demonstrated that patients with EAC showing MELF pattern had several adverse clinicopathological characteristics reflecting aggressive behavior. On the other hand, since the frequencies of post-operative recurrence and disease-related mortality that occurred during the follow-up period were relatively low, further investigations are warranted to clarify the prognostic value of MELF pattern in EAC patients.

Ovarian RASoma With Mesonephric-like Adenocarcinoma and Mixed Mullerian Components: A Case Report With Molecular Analysis Demonstrating Multidirectional Mullerian Differentiation

Gynecologic carcinomas with RAS mutations may show a wide spectrum of histologic types, including mixed types. We present the case of a 63-yr-old patient diagnosed with an ovarian tumor harboring a mesonephric-like adenocarcinoma in a background of mixed mesonephric-like, mucinous, and endometrioid components. Molecular analysis revealed that all 3 components shared the same clonal KRAS mutation (p.G12A) and chromosome 1q gain. Based on shifts in clonality, copy number gains, and acquisition of an additional mutation, our data suggest that the mucinous component likely constituted the substrate from which the mesonephric-like and endometrioid components arose.

Mesonephric-like Adenocarcinoma of the Uterine Corpus: Clinicopathological and Prognostic Significance of L1 Cell Adhesion Molecule (L1CAM) Over-expression

BACKGROUND/AIM

The expression of L1 cell adhesion molecule (L1CAM) in uterine mesonephric-like adenocarcinoma (MLA) remains understudied. Our aim was to explore the L1CAM expression in uterine MLA, delving into its clinicopathological implications and prognostic significance.

PATIENTS AND METHODS

We conducted L1CAM immunostaining in MLA, endometrioid carcinoma (EC), and serous carcinoma (SC), compared L1CAM expression across these histological types, and probed the relationship between L1CAM expression and the clinicopathological features and outcomes of patients with MLA.

RESULTS

High L1CAM expression was evident in 15 of 28 MLA cases (53.6%). This rate surpassed that of EC (7.5%) but was less than that of SC (78.9%). A high L1CAM expression correlated with initial distant metastasis, advanced initial stage, lung metastasis, and the recurrence of MLA. L1CAM-high MLA exhibited worse disease-free and overall survival than L1CAM-low MLA.

CONCLUSION

L1CAM over-expression was observed in more than half of the MLA cases, and was associated with aggressive clinicopathological traits and adverse outcomes in patients with uterine MLA.

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.

Mesonephric-like Adenocarcinoma of the Uterine Corpus: Comparison Between Mismatch Repair Protein Immunostaining and Microsatellite Instability Testing

BACKGROUND/AIM

The utility of mismatch repair (MMR) immunohistochemistry (IHC) and microsatellite instability (MSI) testing in uterine mesonephric-like adenocarcinoma (MLA) has seldom been reported. This study aimed to compare MMR IHC and MSI testing in uterine MLA.

PATIENTS AND METHODS

We analyzed the MMR protein expression of 25 patients with MLA and compared the results with the MSI status.

RESULTS

Of the cases, one (4.0%) was initially interpreted to have a loss of mutS homolog 2 (MSH2) and mutS homolog 6 (MSH6) expression, and eight (32.0%) to have a loss of MSH6 immunoreactivity. Upon re-evaluation of the slides and repeat IHC, all cases were revealed to demonstrate at least focal (5-20%) immunoreactivity for MSH2 or MSH6. MSI testing revealed all cases to be microsatellite stable (MSS).

CONCLUSION

Uterine MLA is an MSS/MMR-proficient tumor. We observed complete concordance between MMR IHC and MSI testing. MMR IHC should be carefully interpreted, and discordant cases must be thoroughly reviewed. Repeat IHC and confirmatory MSI testing may be beneficial in resolving uncertain cases.

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

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

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

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

Mesonephric-like Adenocarcinoma of the Female Genital Tract: Novel Observations and Detailed Molecular Characterisation of Mixed Tumours and Mesonephric-like Carcinosarcomas

AIMS

To report novel observations in five mesonephric-like adenocarcinomas (MLAs) of the female genital tract.

METHODS AND RESULTS

We report two endometrial MLAs in association with endometrioid carcinoma and atypical hyperplasia and three (one endometrial, two ovarian) cases with a sarcomatoid component (mesonephric-like carcinosarcoma). Pathogenic KRAS mutations, which are characteristic of MLA, were identified in all cases, although interestingly in one of the mixed carcinomas, this was confined to the endometrioid component. The concurrent MLA, endometrioid carcinoma and atypical hyperplasia components in one case harboured identical EGFR, PTEN, and CCNE1 mutations, suggesting that the atypical hyperplasia gave rise to a Müllerian carcinoma with both endometrioid and mesonephric-like components. The carcinosarcomas all contained a component of MLA and a sarcomatous component with chondroid elements. In the ovarian carcinosarcomas, the coexisting epithelial and sarcomatous components shared some mutations including KRAS and CREBBP, suggesting that they are clonally related. Furthermore, in one case CREBBP and KRAS mutations detected in the MLA and sarcomatous components were also detected in an associated undifferentiated carcinoma component, suggesting that it was clonally related to the MLA and sarcomatous components.

CONCLUSIONS

Our observations provide additional evidence that MLAs have a Müllerian origin and characterize mesonephric-like carcinosarcomas in which chondroid elements appear to be characteristic. In reporting these findings, we provide recommendations for distinction between a mesonephric-like carcinosarcoma and a MLA with a spindle cell component.

Cytological features of mesonephric-like adenocarcinoma of the uterine corpus

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Mesonephric Adenocarcinoma and Mesonephric-like Adenocarcinoma of the Urinary Tract

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

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.

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.

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 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.

Ovarian Mesonephric-like Adenocarcinoma With Multifocal Microscopic Involvement of the Fimbrial Surface: Potential for Misdiagnosis of Tubal Intraepithelial Metastasis as Serous Tubal Intraepithelial Carcinoma Associated With Ovarian High-grade Serous Carcinoma

BACKGROUND/AIM

We describe a rare case of ovarian mesonephric-like adenocarcinoma (MLA) involving the fimbria and mimicking serous tubal intraepithelial carcinoma (STIC).

CASE REPORT

A 47-year-old woman presented with a 4.4-cm left ovarian mass. Histologically, the ovarian tumor showed papillary and solid architecture, severe nuclear pleomorphism, and increased mitotic activity. Some microscopic foci where the tumor cells spread horizontally along the fimbrial surface epithelium were noted, compatible with STIC. We initially considered the ovarian tumor to be high-grade serous carcinoma accompanied by a fimbrial STIC. However, immunostaining revealed nuclear immunoreactivity for paired box 2 and GATA-binding protein 3, but lacked expression of Wilms tumor 1. A thorough slide review and additional immunostaining revealed architectural diversity, densely eosinophilic intraluminal secretions, and lack of hormone receptor expression, supporting the diagnosis of MLA.

CONCLUSION

Microscopic intraepithelial metastases of the MLA to the fimbria mimic STIC. We recommend ancillary tests, such as immunostaining, in patients with ovarian tumors whenever possible, particularly for those with differential diagnosis of MLA and high-grade serous carcinoma.

Mesonephric-like adenocarcinoma of the ovary in an elderly woman: A case report and a review of the literature

Mesonephric-like adenocarcinoma (MLA) is a rare tumor that occurs in the uterine endometrium and ovary. It morphologically and immunohistochemically resembles cervical mesonephric adenocarcinoma (MA). Here, we present a case of MLA of the ovary along with a literature review. An asymptomatic 84-year-old woman presented with a pelvic mass, detected by computerized tomography. Magnetic resonance imaging demonstrated a polycystic mass with a solid component in the left adnexal region. The solid component showed low signal intensity on T2-weighted imaging and high signal intensity on diffusion-weighted imaging. We strongly suspected an ovarian malignant tumor; therefore, surgical resection of the uterus and adnexa was performed. Macroscopically, the tumor was predominantly solid with yellowish-tan cut surface. Microscopically, it showed a tubular pattern with intraluminal colloid-like material resembling MA. The tumor cells were negative for estrogen receptor, calretinin, and CD10 and positive for PAX8 and TTF-1. These findings are consistent with those of MLA.

Mesonephric-like Differentiation of Ovarian Endometrioid and High-grade Serous Carcinomas: Clinicopathological and Molecular Characteristics Distinct from Those of Mesonephric-like Adenocarcinoma

BACKGROUND/AIM

Ovarian endometrioid carcinoma (EC) and high-grade serous carcinoma (HGSC) may exhibit various growth patterns and mimic mesonephric-like adenocarcinoma (MLA). We investigated the clinicopathological and molecular features of ovarian carcinomas with mesonephric-like differentiation (MLD).

PATIENTS AND METHODS

We analyzed the electronic medical records and pathology slides of two EC-MLD and three HGSC-MLD patients, and conducted immunostaining and targeted sequencing of their samples.

RESULTS

All cases showed architectural diversity, compactly aggregated small tubules and ducts, and eosinophilic intraluminal secretions, indicating the possibility of an ovarian MLA. However, the following histological and immunophenotypical features confirmed the diagnoses of EC-MLD and HGSC-MLD: squamous, tubal, and sertoliform differentiation; serous tubal intraepithelial carcinoma; solid, endometrioid, transitional (SET) feature; solid, transitional, endometrioid, mucinous-like (STEM) feature; diffuse expression of hormone receptors and Wilms tumor 1; mutant p53 immunostaining pattern; and wild-type v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog gene.

CONCLUSION

A subset of ovarian ECs and HGSCs can display MLD and mimic an MLA. A thorough histological examination combined with ancillary tests is crucial to differentiate between these ovarian neoplastic entities.

Mesonephric adenocarcinomas in female genital tract: A case series

ABSTRACT

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

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

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

Dedifferentiated Mesonephric-like Adenocarcinoma of the Uterine Corpus

BACKGROUND/AIM

We present a case of uterine dedifferentiated mesonephric-like adenocarcinoma (MLA).

CASE REPORT

A 54-year-old woman underwent total hysterectomy for a uterine mass under the impression of a uterine sarcoma. Histologically, MLA exhibited various growth patterns including tubular and glandular architecture. Undifferentiated carcinoma (UC) displayed discohesive tumor cells without any obvious architecture. Immunohistochemically, UC was positive for epithelial markers in very few scattered tumor cells. MLA exhibited the wild-type p53 expression pattern, whereas UC showed a uniform and strong p53 immunoreactivity. Targeted sequencing analysis revealed an identical Kirsten rat sarcoma viral oncogene homolog (KRAS) mutation in both components. A pathogenic missense tumor protein 53 (TP53) mutation was detected in UC, but not in MLA.

CONCLUSION

The mutant p53 expression pattern exclusively detected in UC was concordant with the presence of missense TP53 mutation. Our observations suggested that TP53 mutation is associated with the possible transformation from MLA to UC.

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.

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.

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.

Mesonephric proliferations of the female genital tract

The mesonephric (Wolffian) duct regresses in females during embryological development. Remnants of this duct may persist typically along the lateral walls of the cervix, vagina, adnexa, and uterine corpus. These mesonephric epithelia may expand into hyperplastic proliferations and rarely form neoplasms. The spectrum of morphology, immunophenotype, clinical presentation, and molecular characteristics of mesonephric lesions is reviewed, with attention to distinction from entities in the differential diagnosis.