Mesonephric adenocarcinomas of the uterine cervix: a study of 11 cases with immunohistochemical findings

Premature Classification of Early-stage Endometrioid Ovarian Carcinoma With Mesonephric-like Differentiation as Mesonephric-like Adenocarcinoma

Ovarian mesonephric-like adenocarcinoma (MLA) is a rare tumor with potential origins in endometriosis and Müllerian-type epithelial tumors. The morphologic patterns of MLA overlap with those of endometrioid ovarian carcinoma (EnOC). We speculated that a subset of MLAs would be classified as EnOCs. In this study, we attempted to identify MLAs from malignant endometrioid tumors. Given that the study patients with MLAs had both endometrioid-like and mesonephric-like morphologies, we defined mesonephric-like differentiation (MLD) as an endometrioid tumor with focal or diffuse MLA morphology and immunophenotype. Twelve patients exhibited mesonephric-like morphologic patterns. Immunohistochemistry analysis for CD10, TTF-1, estrogen receptor (ER), GATA3, calretinin, and PAX8 expression was done using whole-section slides. Two patients without the MLA immunophenotype were excluded. Ten patients with EnOCs with MLD (8.3%) were identified from a cohort of 121 patients with malignant endometrioid tumors. All 10 patients were positive for TTF-1 and/or GATA3. Most patients were ER-negative. Morphologically, MLD was associated with papillary thyroid carcinoma-like nuclei, flattened cells, tubular, nested, reticular, or glomeruloid architecture, and infiltrative growth. All 10 patients had pre-existing endometriosis and/or adenofibromas. Among the EnOCs with MLD, 5 had coexisting components such as EnOC grade 1 [(G1), cases 4, 7, and 9], mucinous borderline tumor (case 1), and dedifferentiated carcinoma (case 10), with distinct borders between EnOC with MLD and the other components. Nine of the 10 MLA patients (90%) harbored KRAS hotspot mutations. In addition, 4 patients harboring other components shared common KRAS hotspot mutations. No significant prognostic differences were observed between patients with and without MLD. Based on our findings, we suggest that EnOC with MLD, especially in the early stages and without high-grade components, should be considered a subtype of EnOC. Overtreatment should be avoided in such patients, particularly in the early stages. In this study, as the characteristics between EnOC with MLD and MLA were not distinguishable, we considered both conditions to be on the same spectrum. EnOCs with MLD exhibit the MLA phenotype during disease progression and are prematurely classified as MLA. Nevertheless, more patients with EnOC who have MLD/MLA are required for a more robust comparison between conventional EnOC according to staging and grading.

Endometrial cytological findings for a mesonephric-like endometrial adenocarcinoma: A case report

A mesonephric-like endometrial adenocarcinoma (ML-EAC) is very rare and has a worse prognosis than other endometrial carcinomas. We describe an ML-EAC and report our endometrial cytological findings. A 76-year-old woman presented with irregular genital bleeding and a uterine mass. Endometrial cytology revealed atypical cylindrical or spindle-shaped cells in the form of small aggregates or solitary cells. The cell aggregates exhibited irregularly stacked papillary structures, small glandular structures, and fenestrated structures. The atypical cells had a nucleus with fine-granular chromatin and a granular cytoplasm, and nuclear grooves and intranuclear pseudo-inclusions were present. Hyaline globules were observed in the glandular lumens and in the background. The presumptive histological type was an adenocarcinoma, but the cytological features were different from those of an endometrioid carcinoma. A histological examination of the endometrial biopsy revealed an adenocarcinoma, and a simple hysterectomy was performed. A grayish-white elevated mass measuring 90 mm × 70 mm × 40 mm was observed on the uterine corpus in the hysterectomy specimen. Histologically, the tumor proliferated as complex tubular structures containing eosinophilic colloid-like materials and trabecular structures. The tumor cells were diffuse and positive for GATA-3 and partially positive for thyroid transcription factor-1. Estrogen and progesterone receptors were negative. An ML-EAC was diagnosed. The tumor was invasive and extended beyond one-half of the muscle layer with a high degree of vascular invasion. In conclusion, we need to focus on the various shapes of the cell aggregate, nuclear grooves, and intranuclear pseudo-inclusions of tumor cells to distinguish an ML-EAC from other endometrial carcinomas in endometrial cytology.

Carbon ion radiotherapy for mesonephric adenocarcinoma of the uterine cervix: a case report

BACKGROUND

Mesonephric adenocarcinoma is an extremely rare subtype of uterine cervical cancer that is associated with a poor prognosis and for which a standardized treatment protocol has not been established. Carbon ion radiotherapy (CIRT) is an emerging radiotherapy modality that has been shown to have a favorable anti-tumor effect, even for tumors resistant to conventional photon radiotherapy or chemotherapy. However, there is no report on CIRT outcomes for mesonephric adenocarcinoma of the uterine cervix.

CASE PRESENTATION

We treated a 47-year-old Japanese woman with mesonephric adenocarcinoma of the uterine cervix (T2bN0M0 and stage IIB according to the 7th edition of the Union for International Cancer Control and International Federation of Gynecology and Obstetrics, respectively) with CIRT combined with brachytherapy and concurrent chemotherapy. CIRT consisted of whole pelvic irradiation and boost irradiation to the gross tumor; 36.0 Gy (relative biological effectiveness [RBE]) in 12 fractions and 19.2 Gy (RBE) in 4 fractions, respectively, performed once a day, four times per week. Computed tomography-based image-guided adaptive brachytherapy was performed after completion of CIRT, for which the D90 (i.e., the dose prescribed to 90% of the target volume) for the high-risk clinical target volume was 20.4 Gy in a total of 3 sessions in 2 weeks. A weekly cisplatin (40 mg/m2) dose was administered concomitantly with the radiotherapy for a total of five courses. From 4 months post-CIRT, the patient developed metastasis of the lung, with a total of 10 lung metastases over 70 months; these lesions were treated on each occasion by photon stereotactic body radiotherapy and/or systemic therapy. At 8 years from initial treatment (i.e., 2 years after the last treatment), the patient is alive without any evidence of recurrence and maintains a high quality of life.

CONCLUSIONS

This is the first report of CIRT for treatment of mesonephric adenocarcinoma of the uterine cervix. The present case indicates the potential efficacy of CIRT in combination with brachytherapy for treatment of this disease.

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

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

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

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

Cytological features of mesonephric-like adenocarcinoma of the uterine corpus

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Mesonephric Adenocarcinoma and Mesonephric-like Adenocarcinoma of the Urinary Tract

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

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

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

New Insights in the Diagnosis of Rare Adenocarcinoma Variants of the Cervix—Case Report and Review of Literature

We report the case of a 29-year-old patient with low-grade squamous intraepithelial lesion (L-SIL), negative human papilloma virus (HPV), positive p16/Ki-67 dual-staining and colposcopy suggestive for severe dysplastic lesion. The patient underwent a loop electrosurgical excision procedure (LEEP), the pathology report revealing mesonephric hyperplasia and adenocarcinoma. The patient also opted for non-standard fertility-sparing treatment. The trachelectomy pathology report described a zone of hyperplasia at the limit of resection towards the uterine isthmus. Two supplementary interpretations of the slides and immunohistochemistry (IHC) were performed. The results supported the diagnosis of mesonephric adenocarcinoma, although with difficulty in differentiating it from mesonephric hyperplasia. Given the discordant pathology results that were inconclusive in establishing a precise diagnosis of the lesion and the state of the limits of resection, the patient was referred to a specialist abroad. Furthermore, the additional interpretation of the slides and IHC were performed, the results suggesting a clear cell carcinoma. The positive p16/Ki-67 dual-staining prior to LEEP, the non-specific IHC and the difficulties in establishing a diagnosis made the case interesting. Given the limitations of cytology and the fact that these variants are independent of HPV infection, dual staining p16/Ki-67 could potentially become useful in the diagnosis of rare adenocarcinoma variants of the cervix, however further documentation is required.

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

Background

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

Methods

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

Results

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

Conclusions

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

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

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

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

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

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.

Molecular Pathology of Human Papilloma Virus-Negative Cervical Cancers

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

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

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

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.

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.

Carcinomas of the Uterine Cervix: Comprehensive Review With An Update on Pathogenesis, Nomenclature of Precursor and Invasive Lesions, and Differential Diagnostic Considerations

Most cervical carcinomas and their related lesions are attributed to an infection by human papillomavirus (HPV). The infection usually starts in the basal cells at the squamocolumnar junction. It causes cell proliferation and maturation abnormalities along with nuclear abnormalities resulting in low-grade squamous intraepithelial lesions. An overwhelming majority of these lesions spontaneously disappear, and the infection is cleared. In a small subset of high-risk HPV infection cases, the lesions may persist and progress to high-grade squamous intraepithelial lesions. These are associated with the incorporation of the viral genome into the human genome. Some of the high-grade squamous intraepithelial lesions, over several years, progress to invasive carcinoma. Carcinomas of the cervix are usually squamous cell carcinomas (SCCs), but 20% to 25% of the cases may manifest as adenocarcinomas. Similar to SCC, adenocarcinomas may initially manifest as adenocarcinomas in situ and may progress to invasive carcinomas after a variable period of time. In the recently published World Health Organization classification of female genital tumors, SCCs, and adenocarcinomas of the cervix are divided into HPV-associated and HPV-independent tumors. This review draws on the latest terminology and the several morphologic subtypes recognized for each category.

Cervical Mesonephric Adenocarcinoma: A Case Report of a Rare Gynecological Tumor from Embryological Remains of the Female Genital Tract

INTRODUCTION

 Malignant mesonephric tumors are uncommon in the female genital tract, and they are usually located where embryonic remnants of Wolffian ducts are detected, such as the uterine cervix. The information about these tumors, their treatment protocol, and prognosis are scarce.

CASE REPORT

 A 60-year-old woman with postmenopausal vaginal bleeding was initially diagnosed with endometrial carcinoma. After suspicion co-testing, the patient underwent a loop electrosurgical excision of the cervix and was eventually diagnosed with mesonephric adenocarcinoma. She was subjected to a radical hysterectomy, which revealed International Federation of Gynecology and Obstetrics (FIGO) IB1 stage, and adjuvant radiotherapy. The follow-up showed no evidence of recurrence after 60 months.

CONCLUSION

 We present the case of a woman with cervical mesonephric adenocarcinoma. When compared with the literature, this case had the longest clinical follow-up without evidence of recurrence, which reinforces the concept that these tumors are associated with a favorable prognosis if managed according to the guidelines defined for the treatment of patients with cervical adenocarcinomas. Though a rare entity, it should be kept in mind as a differential diagnosis for other cervical cancers.

Grading of Endocervical Adenocarcinomas: Review of the Literature and Recommendations From the International Society of Gynecological Pathologists

There is a lack of consensus regarding the prognostic value of grading endocervical adenocarcinomas and currently, no universally applied, validated system for grading exists. Several grading schemes have been proposed, most incorporating an evaluation of tumor architecture and nuclear morphology and these are often based on the International Federation of Gynecology and Obstetrics (FIGO) system for endometrial endometrioid carcinoma, although some schemes modify the proportion of solid tumor required to separate grades 1 and 2 from 5% to 10%. In the absence of a validated system, we endorse this approach for most human papillomavirus-associated endocervical adenocarcinomas and, based on the available evidence, recommend that tumors with ≤10% solid growth be designated grade 1, 11% to 50% solid growth grade 2 and >50% solid growth grade 3. Tumors should be upgraded in the presence of marked nuclear atypia involving the majority (>50%) of the tumor. Grading is not recommended for human papillomavirus-independent adenocarcinomas, since no validated system has been suggested and most of these neoplasms exhibit intrinsically aggressive behavior regardless of their morphologic appearance. Importantly, grading should not be performed for gastric-type adenocarcinomas, particularly as these tumors may appear deceptively "low-grade" yet still exhibit aggressive behavior. Recently devised, validated and reproducible etiology and pattern-based tumor classification systems for endocervical adenocarcinomas appear to offer more effective risk stratification than tumor grading and, in the future, these systems may render the provision of a tumor grade redundant.

Clear Cell Adenocarcinoma in Men: A Series of 15 Cases

Clear cell adenocarcinoma (CCA) is a rare tumor in the genitourinary tract with female predominance and few reports in men. We identified 15 cases of CCA in men evaluated at our institution. Five arose in the bladder, 7 in the prostate or prostatic urethra, 2 in the membranous urethra (1 multifocal in the prostatic and membranous urethra), 1 periprostatic (likely from an embryologic remnant), and 1 between rectum and bladder (likely in a prostatic utricle cyst). No cases showed associated Müllerian structures. One case showed separate foci of nephrogenic adenoma at diagnosis, and 1 case showed urothelial carcinoma in situ on a later follow-up biopsy. Four tumors extended into other organs (prostate to seminal vesicle and periprostatic soft tissue, periprostatic soft tissue to prostate, prostatic urethra to bladder and rectum, and prostate to bladder neck). One tumor showed extraprostatic extension alone. Four tumors metastasized to lymph nodes, with 3 also metastasizing to other sites (bladder, lung and adrenal, and right flank). Eleven patients underwent resection, including 3 transurethral resections. Seven underwent other treatments, including radiation (5 [1 for recurrence]), chemotherapy (3), hormonal therapy (3), immunotherapy with nivolumab (1), and targeted therapy with gefitinib (1). The mean follow-up was 35 months (range: 1 to 138 mo). At the last follow-up, 7 patients showed no evident disease and 3 were alive with disease. Four died with the cause of death unknown, with 2 cases having confirmed disease at the time of death and the remaining 2 dying less than a year after diagnosis. The mean time to death was 16 months (range: 6 to 39 mo). No follow-up was available on 1 patient. All patients who died in this series had CCA of the prostate or prostatic urethra. Pathologists need to be attuned to CCA occurring in males, given that the literature emphasizes its occurrence in females. In addition to established sites such as bladder and urethra, our series demonstrates that tumor may present in unusual adjacent sites, such as in periprostatic embryologic remnants or prostatic utricle.

Incidental mesonephric remnant hyperplasia of the jejunal mesentery: A diagnostic challenge

Mesonephric remnants are embryonic vestiges of the mesonephric (Wolffian) ducts which regress during normal development. These remnants have been uncommonly reported in the female and male reproductive tract as a spectrum of morphologic lesions that can be misdiagnosed as carcinoma. One case of mesonephric remnant hyperplasia of the jejunal mesentery incidentally found in a 47-year-old man is herein reported. This is the first description of mesonephric hyperplasia arisen in the mesentery. The presence of ducts, tubules, and cysts lined by bland, epithelial, cuboidal cells with scant cytoplasm, and diffuse pseudoinfiltrative growth pattern can raise the possibility of neoplasia. Immunohistochemically, mesonephric epithelia have a characteristic staining. CD10 highlights the apical-luminal aspect of the cells. Besides, intense reactivity is showed for high-molecular-weight cytokeratin (CK), CK7, bcl2, and vimentin. The main differential diagnosis includes mesothelial hyperplasia, epithelial mesothelioma, well-differentiated neuroendocrine tumor, and infiltration due to acinar adenocarcinoma of the prostate. However, a detailed microscopic study with the aid of immunohistochemistry helps separate mesonephric remnants from malignant processes. The mesonephric hyperplasia of the mesentery we have reported adds to the spectrum of mesonephric remnants a new location. Familiarity with this lesion is indispensable to avoid overdiagnosis.

Mesonephric Adenocarcinoma of Uterine Cervix: A Case Report and Review of the Literature

Mesonephric adenocarcinoma of the uterine cervix is an extremely rare tumor of the female genital tract which derives from the remnants of embryonic mesonephric ducts and its prognosis, diagnosis and treatment is rather challenging. We report a case of a 46-year-old woman with history of abnormal uterine bleeding and an enlarged uterine cervix on physical examination without obvious mass lesion. She was clinically underdiagnosed with cervical myoma and mesonephric hyperplasia. After simple hysterectomy, stage IB2 mesonephric adenocarcinoma was diagnosed. Despite adjuvant chemoradiation, she presented with peritoneal and locoregional recurrence in less than a year. So, in the presence of abnormal bleeding and cervical mass, mesonephric hyperplasia in cervical biopsy specimen should be suspected for adenocarcinoma. Radical hysterectomy and complete staging with or without salpingo-oophorectomy is the mainstay of treatment. Despite all ambiguities, due to the small number of reported cases, the overall prognosis seems to be less favorable than conventional cervical adenocarcinoma.

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

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

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

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

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

Cervical adenocarcinoma: integration of HPV status, pattern of invasion, morphology and molecular markers into classification

Cervical adenocarcinoma is a heterogenous group of tumours with various aetiologies, molecular drivers, morphologies, response to treatment and prognosis. It has become evident that human papillomavirus (HPV) infection does not drive all adenocarcinomas, and appropriate classification is critical for patient management, especially in the era of the HPV vaccine and HPV-only screening. Identified as one of the most important developments in gynaecological pathology during the past 50 years, the separation of cervical adenocarcinomas into HPV-associated (HPVA) and HPV-independent has resulted in a transformation of the classification system for cervical adenocarcinomas. HPVA has been traditionally subclassified by morphology, such as usual type (UEA), mucinous and villoglandular, etc. However, it has become evident that cell type-based histomorphological classification is not clinically meaningful, and the newly proposed International Endocervical Adenocarcinoma Criteria and Classification (IECC) is a necessary and relevant break from this prior system. Non-HPV-associated adenocarcinomas can be divided by their distinct morphology and molecular genomics with very different responses to standard therapies and potential for future targeted therapies. These include gastric-type, clear-cell, mesonephric and endometrioid adenocarcinomas. So-called 'serous' carcinomas of the cervix probably represent morphological variants of UEA or drop metastases from uterine or adnexal serous carcinomas, and the existence of true cervical serous carcinomas is in question. This review will discuss the advances since WHO 2014, and how HPV status, pattern of invasion as described by Silva and colleagues, histological features and molecular markers can be used to refine diagnosis and prognostication for patients with cervical adenocarcinoma.

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 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 adenocarcinoma of the uterine cervix with rare lung metastases: A case report and review of the literature

BACKGROUND

Mesonephric adenocarcinoma (MNA) of the female reproductive system is a rare tumor arising from remnants of the mesonephric duct, which is mainly located in the cervix. MNA often occurs in adult women. Due to the rarity of the disease and few reports, the specific clinical features have not been established.

CASE SUMMARY

We present a case of a cervical MNA in a 48-year-old woman with an incidental intra-operative diagnosis who received postoperative chemotherapy. Rare lung metastases were detected during follow-up. The existing literature is reviewed.

CONCLUSION

The clinical manifestations, pathological characteristics, diagnosis, treatment, and prognosis of MNA have been summarized through the review of the existing literature and the case in this paper. Due to the rarity of this disease, it is very important for the research of MNA in the future.

A Comprehensive Review of Biomarker Use in the Gynecologic Tract Including Differential Diagnoses and Diagnostic Pitfalls

Morphologic (ie, hematoxylin and eosin) evaluation of the Mullerian tract remains the gold standard for diagnostic evaluation; nevertheless, ancillary/biomarker studies are increasingly utilized in daily practice to assist in the subclassification of gynecologic lesions and tumors. The most frequently utilized "biomarker" technique is immunohistochemistry; however, in situ hybridization (chromogenic and fluorescence), chromosomal evaluation, and molecular analysis can also be utilized to aid in diagnosis. This review focuses on the use of immunohistochemistry in the Mullerian tract, and discusses common antibody panels, sensitivity and specificity of specific antibodies, and points out potential diagnostic pitfalls when using such antibodies.

Female adnexal tumors of probable Wolffian origin: morphological, immunohistochemical, and molecular analysis of 15 cases

Female adnexal tumors of probable Wolffian origin are rare and present a diagnostic challenge due to their morphological and immunohistochemical overlap with more common ovarian and broad ligament entities. We evaluated the morphological, immunohistochemical, and molecular features of 15 tumors of probable Wolffian origin. Patients ranged from 32 to 69 (mean 47) years and tumors from 1.8 to 30 (mean 10) cm. All except one arose in para-adnexal soft tissues. Follow-up was available for six patients, five of whom were alive and well, while the sixth, who had extra-adnexal disease at diagnosis, died from unrelated causes. The following patterns were noted: tubular (all tumors), solid 11/15 (73%), sieve-like 7/15 (47%), and reticular 1/15 (7%). A myxoid background was present in 3/15 (20%) of tumors and eosinophilic luminal secretions in 11/15 (73%). Most tumors (12/15, 80%) had low-grade nuclear atypia, while three showed foci with scattered high-grade atypia. Mitotic index ranged from 0 to 17 (mean 4) per ten high-power fields. Tumors were positive for pankeratin and negative for TTF-1. EMA, GATA3, and PAX8 were positive in 2/10 (20%; focal), 3/15 (20%; focal), and 1/15 (7%; focal) of tumors, respectively. CD10, SF-1, calretinin, inhibin, ER, PR, cytokeratin 7, and WT1 were variably expressed. Pathogenic mutations were rare and included STK11 (n = 3), APC (n = 1), and MBD4 (n = 1). Copy number variations were detected in the three tumors with STK11 mutations and a myxoid background. These data demonstrate that female adnexal tumors of probable Wolffian origin are morphologically and immunohistochemically diverse, but infrequently harbor pathogenic mutations. However, their lack of mutations in contrast to their mimickers may be a valuable tool in diagnostically difficult cases.

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.

A Combined Morphologic and Molecular Approach to Retrospectively Identify KRAS-Mutated Mesonephric-like Adenocarcinomas of the Endometrium

An unusual subset of endometrial carcinoma, the mesonephric-like adenocarcinomas, are morphologically and molecularly similar to mesonephric carcinoma, characterized by KRAS mutation and lack of microsatellite instability. They also have a unique immunohistochemical profile and are usually positive for GATA-3, CD10, TTF-1, and negative for ER and PR. This study implemented a combined morphologic and molecular approach to retrospectively identify mesonephric-like carcinomas of the endometrium. KRAS-mutated microsatellite stable (MSS) endometrial carcinomas were identified from a database of 570 endometrial carcinomas that had undergone massively parallel sequencing. MSS tumors with canonical KRAS mutations that lacked features diagnostic of endometrioid carcinoma (including squamous or mucinous differentiation), were re-reviewed for morphologic features of mesonephric-like adenocarcinomas. Ninty-eight of 570 endometrial carcinomas (17%) harbored canonical KRAS mutations. Of the KRAS-mutated cases, 80 (82%) were MSS and 18 (18%) had microsatellite instability. Of the KRAS-mutated MSS cases with morphology review, 39/61 (64%) had squamous and/or mucinous differentiation while 22 (36%) lacked these histotype-defining features. Eight of these 22 had PTEN mutations and lacked morphologic features of mesonephric-like adenocarcinoma, leaving 14 cases with a possible mesonephric-like adenocarcinoma-like molecular profile that underwent detailed morphologic re-review. Ten of 14 had morphology typical of serous (3), carcinosarcoma (4), or endometrioid (3) carcinoma. In 4 cases, there was striking morphologic, immunophenotypic, and molecular resemblance to mesonephric carcinoma, leading to re-classification as mesonephric-like adenocarcinoma. Two of the 4 cases presented at an advanced stage, and a third case later developed distant metastases. On the basis of this retrospective study, KRAS-mutated mesonephric-like adenocarcinoma represents ∼1% of all endometrial carcinomas. Future prospective recognition of this unusual variant of endometrial carcinoma may be important given its possible aggressive nature.

Recent advances in invasive adenocarcinoma of the cervix

Endocervical adenocarcinomas (ECAs) are currently classified according to the 2014 World Health Organization (WHO) system, which is predominantly based on descriptive morphologic characteristics, considers factors bearing minimal etiological, clinical, or therapeutic relevance, and lacks sufficient reproducibility. The 2017 International Endocervical Adenocarcinoma Criteria and Classification (IECC) system was developed by a group of international collaborators to address these limitations. The IECC system separates ECAs into two major groups-those that are human papillomavirus-associated (HPVA) and those that are non-HPV-associated (NHPVA)-based on morphology (linked to etiology) alone, precluding the need for an expensive panel of immunohistochemical markers for most cases. The major types of HPVA ECA include the usual (with villoglandular and micropapillary architectural variants) and mucinous types (not otherwise specified [NOS], intestinal, signet-ring, and invasive stratified mucin-producing carcinoma). Invasive adenocarcinoma NOS is morphologically uninformative, yet considered part of this group when HPV positive. NHPVA ECAs include gastric, clear cell, endometrioid, and mesonephric types. The IECC system is supported by demographic and clinical features (HPVA ECAs develop in younger patients, are smaller, and are diagnosed at an earlier stage), p16/HPV status (almost all HPVA ECAs are p16 and/or HPV positive), prognostic parameters (NHPVA ECAs more often have lymphovascular invasion, lymph node metastases, and are Silva pattern C), and survival data (NHPVA ECAs are associated with worse survival). A move from the morphology-based WHO system to the IECC system will likely provide clinicians with an improved means to diagnose and classify ECAs, and ultimately, to better personalize treatment for these patients.

A Comparison of GATA3, TTF1, CD10, and Calretinin in Identifying Mesonephric and Mesonephric-like Carcinomas of the Gynecologic Tract

Mesonephric carcinomas of the gynecologic tract are neoplasms that are often under-recognized due to their varied morphologic appearances. Recently, GATA3 and TTF1 have been reported to be useful immunohistochemical markers for distinguishing mesonephric carcinomas from its morphologic mimics. Herein, we compared the performance of GATA3 and TTF1 to the traditional markers used for mesonephric carcinomas, CD10 and calretinin. We studied 694 cases: 8 mesonephric carcinomas (7 cervical [includes 3 mesonephric carcinosarcomas], 1 vaginal), 5 mesonephric-like carcinomas (4 uterine corpus, 1 ovarian), 585 endometrial adenocarcinomas, and 96 cervical adenocarcinomas. Mesonephric-like carcinomas were defined as tumors exhibiting the classic morphologic features of mesonephric carcinoma, but occurring outside of the cervix and without convincing mesonephric remnants. GATA3 had the highest sensitivity and specificity (91% and 94%) compared with TTF1 (45% and 99%), CD10 (73% and 83%), and calretinin (36% and 89%). GATA3, however, also stained a substantial number of uterine carcinosarcomas (23/113, 20%). TTF1 was positive in 5/5 (100%) mesonephric-like carcinomas and only 1/8 (13%) mesonephric carcinomas. In 4/6 (67%) TTF1 positive cases, GATA3 exhibited an inverse staining pattern with TTF1. In summary, GATA3 was the best overall marker for mesonephric and mesonephric-like carcinomas, but cannot be used to distinguish mesonephric carcinosarcomas from Müllerian carcinosarcomas. The inverse staining pattern between GATA3 and TTF1, suggests that TTF1 may be useful when GATA3 is negative in small biopsies where mesonephric or mesonephric-like carcinoma is suspected. The greater TTF1 positivity in mesonephric-like carcinomas suggests they may be biologically different from prototypical mesonephric carcinomas.

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.

Diagnostic Algorithmic Proposal Based on Comprehensive Immunohistochemical Evaluation of 297 Invasive Endocervical Adenocarcinomas

The International Endocervical Adenocarcinoma Criteria and Classification was developed to separate endocervical adenocarcinomas (ECAs) into 2 main categories on the basis of morphology such as human papilloma virus-associated (HPVA) and non-human papilloma virus-associated adenocarcinomas. We aimed to improve the diagnostic accuracy of International Endocervical Adenocarcinoma Criteria and Classification by performing a comprehensive immunohistochemical evaluation and constructing objective immunohistochemical-based algorithms for the classification of these tumors. Tissue microarrays were constructed from 297 of 409 cases used to develop the original classification. Immunostains included p16, p53, estrogen receptor (ER), progesterone receptor, androgen receptor, Vimentin, CK7, CK20, HER2, HIK1083, MUC6, CA-IX, SATB2, HNF-1beta, napsin A, PAX8, CDX2, GATA3, p63, p40, and TTF-1. High-risk human papilloma virus (HR-HPV) was detected by in situ hybridization (ISH) using probes against E6 and E7 mRNA expressed in 18 different virus types. Vimentin, ER, and progesterone receptor were expressed in a significant minority of ECAs, mostly HPVAs, limiting their use in differential diagnosis of endometrioid carcinoma when unaccompanied by HPV-ISH or p16. HR-HPV ISH had superior sensitivity, specificity, and negative and positive predictive values compared with p16, as published previously. HNF-1beta did not have the anticipated discriminatory power for clear cell carcinoma, nor did MUC6 or CA-IX for gastric-type carcinoma. HNF-1beta and napsin A were variably expressed in clear cell carcinoma, with HNF-1beta demonstrating less specificity, as it was ubiquitously expressed in gastric-type carcinoma and in the majority of HPV-associated mucinous (predominantly intestinal-type and invasive ECA resembling stratified mucin-producing intraepithelial lesion [iSMILE]) and usual-type carcinomas. HIK1083 was expressed in nearly half of gastric-type carcinomas, but not in the vast majority of other subtypes. GATA3 was positive in 10% of usual-type adenocarcinomas and in single examples of other subtypes. Rare gastric-type and HPVA mucinous carcinomas displayed HER2 overexpression. Androgen receptor was positive in 6% of usual-type adenocarcinomas. Aberrant p53 expression was found in only 3.6% of usual-type HPVA carcinomas, but it was more prevalent in mucinous (intestinal type and iSMILE) HPVAs and non-human papilloma virus-associates (particularly in gastric-type carcinoma, >50% of cases). The following diagnostic classification algorithms were developed with the above data. Carcinomas without overt cytoplasmic mucin (endometrioid, usual-type endocervical, clear cell, and mesonephric carcinomas) can be subclassified using HR-HPV ISH, ER, and GATA3, whereas carcinomas with easily appreciated cytoplasmic mucin (endometrioid carcinoma with mucinous features, HPVA mucinous, and gastric-type carcinomas) can be subclassified with HR-HPV ISH and ER.

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.

Cervical Glandular Neoplasia: Classification and Staging

Endocervical adenocarcinomas (EAs) account for 25% of all primary cervical carcinomas. Approximately 85% of EAs are driven by high-risk human papillomavirus (HPV) infection, the most common of which is the so-called usual type endocervical adenocarcinomas. Non-HPV-driven subtypes harbor distinct clinicopathologic features and prognosis and have been increasingly recognized in recent years, which has led to efforts to improve classification of EA based on clinically relevant and reproducible criteria. This review discusses a recently proposed classification system, the International Endocervical Adenocarcinoma Criteria and Classification, which uniquely integrates morphology, cause/pathogenesis, and biological behavior of HPV and non-HPV-driven subtypes of EA.

Carcinosarcoma of the uterine cervix: a rare pathological finding originating from mesonephric remnants

Carcinosarcoma of the uterine cervix is a very rare tumour that has been described in less than 70 cases in the literature. It is less common compared with carcinosarcoma of the uterine corpus and it can have two origins: the Müllerian ducts and the mesonephric duct remnants. The association of mesonephric carcinoma with a sarcomatous component was reported in only 11 cases, including the following. We describe a case of a 64-year-old woman, presenting with vaginal bleeding and a cervical lesion reported as a sarcoma of endometrial stroma in the first biopsy. After exclusion of distant disease, she was submitted to radical surgery and the final histopathological examination showed a carcinosarcoma of the cervix with mesonephric origin.

Adenocarcinoma of the uterine cervix: Pathologic features, treatment options, clinical outcome and prognostic variables

Adenocarcinoma accounts for 10-25% of all cervical cancers, and its relative and absolute rate has raised over the past decades. Most, but not all the authors, reported that adenocarcinoma has a greater propensity to lymph node, ovarian and distant metastases and a worse prognosis compared with squamous cell carcinoma. However, whether histologic type is an independent prognostic factor is still a debated issue. Moreover, adenocarcinoma is a very heterogenous disease, including different histological subtypes. Whereas radical hysterectomy and definitive radiotherapy achieve the same clinical outcome in early stage squamous cell carcinoma, surgery seems to obtain better survival compared with definitive radiotherapy in early stage adenocarcinoma. Chemoradiation is the standard treatment for locally advanced cervical cancer regardless of histologic type, although several retrospective studies showed that patients with adenocarcinoma were more likely to die than those with squamous cell carcinoma both before and after concurrent chemoradiation era. The prognostic relevance of biological variables, such as cyclin-dependent kinase inhibitors, p53, cyclooxygenase-2 [COX-2], cell surface tyrosine-kinases and programmed death-ligand [PD-L1], is still under investigation. Palliative chemotherapy is the only treatment option for persistent or recurrent cervical adenocarcinoma not amenable with surgery and radiotherapy. The use of immune checkpoint inhibitors as well as a therapeutic strategy targeting cell surface tyrosine kinases should be adequately explored in this clinical setting.

Cervical Adenocarcinomas: A Heterogeneous Group of Tumors With Variable Etiologies and Clinical Outcomes

Context.—

Cervical adenocarcinomas are a heterogeneous group of tumors with varying morphologies, etiologies, molecular drivers, and prognoses, comprising approximately 25% of all cervical cancers. Unlike cervical squamous cell carcinoma, adenocarcinomas are not uniformly caused by high-risk human papillomavirus (HPV) infection and, therefore, would not necessarily be prevented by the HPV vaccine.

Objective.—

To provide a review of endocervical adenocarcinoma subtypes and, when appropriate, discuss precursor lesions, etiologies, molecular genetics, and ancillary studies within the context of clinical care. Some historical perspectives will also be provided.

Data Sources.—

Data sources included published peer-reviewed literature and personal experiences of the senior author.

Conclusions.—

Endocervical adenocarcinomas are a histologically diverse group of tumors with various causes and molecular drivers, not all related to HPV infection. Distinguishing them has important implications for treatment and prognosis as well as strategies for prevention.

International Endocervical Adenocarcinoma Criteria and Classification: Validation and Interobserver Reproducibility

The current World Health Organization (WHO) classification for endocervical adenocarcinoma (EA) is based on descriptive morphologic characteristics; however, it does not fully reflect our current knowledge of the diverse pathogenesis of cervical glandular neoplasia. A novel classification system, the International Endocervical Adenocarcinoma Criteria and Classification (IECC), which incorporates etiology and biological behavior into the morphologic scheme, has been recently proposed. We aimed to validate the IECC by assessing its interobserver reproducibility in comparison to the WHO system. A cohort of 75 EAs was reviewed independently by 7 gynecologic pathologists and categorized following IECC and WHO criteria based on hematoxylin and eosin material alone and after immunohistochemistry results for p16, PR, p53, Napsin-A, vimentin, CDX2, and GATA3 were provided. Human papillomavirus (HPV) in situ hybridization and polymerase chain reaction results were compared with consensus diagnoses. IECC was superior to WHO in terms of interobserver agreement with κ=0.46 versus 0.3, respectively, on hematoxylin and eosin review and κ=0.51 versus 0.33, respectively, with immunohistochemistry. Under the IECC, 73 (97%) of EAs had majority agreement (≥4 reviewers in agreement) whereas 42 (56%) had perfect agreement (7/7 reviewers in agreement). Conversely, WHO showed majority agreement in 56 (75%) and perfect agreement in only 7 (10%) EAs. Reproducibility was poor in HPV-related WHO types (usual κ=0.36, mucinous not otherwise specified κ=0.13, intestinal κ=0.31, villoglandular κ=0.21) and good in major HPV-unrelated categories (gastric type κ=0.63, clear cell κ=0.81, mesonephric κ=0.5). Classification as per the IECC had excellent correlation with HPV status (by RNA in situ hybridization or polymerase chain reaction). We have shown that the IECC has superior interobserver agreement compared with the WHO classification system, and that distinction between HPV-related and HPV-unrelated EA can be made with good reproducibility and excellent prediction of HPV status. WHO morphologic variants of HPV-related EA are poorly reproducible. Conversely, agreement is high among important high-risk HPV-unrelated subtypes. Thus, our results further support replacing the current WHO classification with the IECC.

Mixed Mesonephric Adenocarcinoma and High-grade Neuroendocrine Carcinoma of the Uterine Cervix: Case Description of a Previously Unreported Entity With Insights Into Its Molecular Pathogenesis

Human papillomavirus (HPV)-negative cervical carcinomas are uncommon and typically encompass unusual histologic subtypes. Mesonephric adenocarcinoma is one such subtype. Mesonephric tumors in the female genital tract are thought to arise from Wolffian remnants, and are extremely rare tumors with widely variable morphology. Sarcomatoid dedifferentiation has been previously described in a few cases, but other forms of dedifferentiation have not been reported. Neuroendocrine carcinoma of the cervix (e.g. small cell carcinoma) is associated with HPV infection, typically HPV 18. These tumors often arise in association with a conventional epithelial component such as squamous cell carcinoma or usual-type endocervical adenocarcinoma. We describe a case of mesonephric adenocarcinoma of the uterine cervix associated with an HPV-negative high-grade neuroendocrine carcinoma at the morphologic and immunophenotypic level, for which we performed targeted massively parallel sequencing analysis of the 2 elements. Both components shared identical mutations in U2AF1 p.R156H (c.467G>A) and GATA3 p.M422fs (c.1263dupG), as well as MYCN amplification. In addition, the neuroendocrine carcinoma harbored TP53 and MST1R mutations not present in the mesonephric carcinoma. Our data suggest a clonal origin of the 2 components of this rare entity, rather than a collision tumor.

Uterine Paramesonephric Cysts in Sprague-Dawley Rats from National Toxicology Program Studies

Congenital uterine wall cysts arising from paramesonephric (Müllerian) and mesonephric (Wolffian) ducts are typically incidental findings in most species. We used immunohistochemistry to characterize and determine the origin of uterine cysts in Sprague-Dawley (SD) rats from multigeneration studies conducted by the National Toxicology Program. Subserosal uterine cysts were observed in 20 of the 2,400 SD rats evaluated in five studies, and 10 cysts were characterized for this study. Single cysts were unilocular, fluid-filled, and occurred throughout the uterus. Microscopically, all cysts had a well-developed smooth muscle wall, lined by flattened to cuboidal, sometimes ciliated, epithelium that stained intensely positive for cytokeratin 18 and paired box protein 8 (PAX8). Most cyst epithelia displayed weak to moderate positivity for progesterone receptor (PR) and/or estrogen receptor α (ER-α), as well as were negative for GATA binding protein 3 (GATA3). Cyst lumens contained basophilic flocculent material. The cysts appeared to be developmental anomalies arising from paramesonephric tissue based on positive PAX8 and ER-α and/or PR staining. Additionally, 70% of the cysts lacked GATA3 expression. Taken together, the subserosal uterine cysts observed in adult rats in these studies most likely arose from the paramesonephric duct.