Practical Updates and Diagnostic Challenges in Endometrial Carcinoma

CONTEXT.—

Clinical management of endometrial carcinoma largely depends on the morphologic parameters ascertained based on the pathologic evaluation of surgical resection specimens. However, there are numerous controversial and nonstandardized aspects of both the macroscopic and microscopic assessment of surgical specimens, including grossing, adequate sampling, diagnosis, staging, reporting, and ancillary testing.

OBJECTIVE.—

To provide a comprehensive practical review of standardized grossing, key morphologic findings for reporting and staging, and diagnostic and prognostic use of ancillary testing in endometrial carcinomas.

DATA SOURCES.—

The existing literature, recommendations of the International Society of Gynecological Pathologists, and specialty consensus guidelines.

CONCLUSIONS.—

This review article summarizes important aspects of the grossing and sampling of surgical resection specimens for microscopic examination, key morphologic parameters that are required for reporting and staging, and morphologic features and immunoprofiles helpful in the differential diagnosis of low-grade and high-grade endometrial carcinomas, as well as the current status of the molecular classification of endometrial carcinoma and human epidermal growth factor receptor 2 testing in serous carcinoma. The information presented herein can be helpful in overcoming diagnostic challenges and issues related to the pathology reporting of endometrial carcinoma to practicing anatomic pathologists.

Patterns of Myometrial Invasion in Endometrial Adenocarcinoma with Emphasizing on Microcystic, Elongated and Fragmented (MELF) Glands Pattern: A Narrative Review of the Literature

Endometrioid endometrial adenocarcinoma (EEC) is the most common malignancy of the female genital tract. According to the 2009 FIGO staging system, the depth of myometrial invasion (MI), and tumor spread to adjacent organs or tissues are the staging criteria for endometrial carcinoma (EC). Therefore, assessment of the depth of MI is of great importance. There is a spectrum of morphological patterns of MI. Still, their number and features vary according to the scientific literature, with a certain overlap that creates difficulties and controversies in the precise assessment of MI depth. The purpose of this review is to present and discuss the most important and recent information about patterns of MI, focusing on the more aggressive and the elongated and fragmented glands (MELF) pattern in particular. Assessment of MI depth and correct staging of EC is possible only after the precise recognition of each MI pattern.

Diagnostic Accuracy in Assessment of Depth of Myometrial Invasion in Low-grade Endometrioid Carcinoma: A 2 Center Comparative Study by MRI and Intraoperative Assessment

The role of lymphadenectomy in endometrial carcinomas is controversial, especially in low-grade endometrioid carcinomas. In many institutions, lymphadenectomy in the latter neoplasms is undertaken only when there is deep myometrial invasion, defined as invasion involving 50% or more of the myometrium (FIGO stage IB). There has been considerable debate as to the best modality to detect deep myometrial invasion. In Europe, preoperative magnetic resonance imaging (MRI) is the most commonly used modality while in North America, intraoperative assessment (IOA) is undertaken in most, but not all, institutions. The aim of this study was to compare the diagnostic accuracy of these 2 modalities in identifying deep myometrial invasion in low-grade endometrioid carcinomas. Two patient cohorts were studied from Belfast, UK (n=253) and Boston, USA (n=276). With respect to detecting deep myometrial invasion, MRI had a sensitivity of 72.84%, positive predictive value of 75.64% and a positive likelihood ratio of 6.59 (95% confidence interval; 4.23-10.28). IOA had a sensitivity of 78.26%, positive predictive value of 80% and a positive likelihood ratio of 20.00 (95% confidence interval; 10.35-38.63). The superior positive likelihood ratio suggests that IOA is better than MRI in determining deep myometrial invasion and the nonoverlapping 95% confidence intervals suggest this is a significant finding. However, there are significant resource implications associated with IOA and preoperative MRI carries other advantages that are discussed herein.

Cervical stromal involvement by endometrial 'hyperplasia': a previously unreported phenomenon with recommendations to report as stage II endometrial carcinoma

A subtle 'burrowing' pattern of cervical stromal involvement by low-grade endometrioid adenocarcinoma of the uterine corpus is described in the literature. We report a small case series in which this pattern of cervical stromal involvement, warranting a diagnosis of endometrioid adenocarcinoma in the cervix, occurred in association with sometimes subtle endometrioid proliferations within the endometrium which fall short of the criteria for endometrioid adenocarcinoma and are in keeping with atypical hyperplasia or hyperplasia without atypia. In reporting this phenomenon, which has not been described previously, we highlight the importance of immunohistochemistry in the differential diagnosis, particularly in the exclusion of primary cervical glandular lesions, including those of mesonephric type. We discuss the differential with primary endometrioid adenocarcinoma (including minimal deviation type) of the cervix and other lesions and stress the importance of sampling the endometrium and lower uterine segment in their entirety in order to exclude an atypical hyperplasia or an adenocarcinoma in these locations. Although the pathogenesis of the cervical lesion we report is controversial, we believe that it is most likely a result of spread from the endometrium and results in the unusual occurrence of the malignant nature of the lesion being only apparent in the secondary rather than the primary lesion. We provide recommendations for reporting such cases and recommend designating them as stage II endometrial carcinoma, although the prognostic and management implications of such cases will only be clear once further cases with follow-up are reported.

[S3 guidelines on the diagnosis and treatment of carcinoma of the endometrium : Requirements for pathology]

The present article summarises the relevant aspects of the S3 guidelines on endometrioid carcinomas. The recommendations include the processing rules of fractional currettings as well as for hysterectomy specimens and lymph node resections (including sentinel lymph nodes). Besides practical aspects, the guidelines consider the needs of the clinicians for appropriate surgical and radiotherapeutic treatment of the patients. Carcinosarcomas are assigned to the endometrial carcinoma as a special variant. For the first time, an algorithmic approach for evaluation of the tumour tissue for Lynch syndrome is given. Prognostic factors based on morphologic findings are summarised.

Pathologic Staging of Endometrial Carcinomas: Selected Areas of Difficulty

Accurate staging of cancers is an important determinant of prognosis and guides optimal patient treatment. Although the International Collaboration on Cancer Reporting recommends that endometrial cancers (including carcinosarcomas) are pathologically staged using the International Federation of Gynecology and Obstetrics (FIGO) 2009 system, in many areas TNM [American Joint Committee on Cancer (AJCC) or Union for International Cancer Control (UICC)] staging is used or even mandated; these latter systems are based on FIGO 2009. In this review, areas of difficulty in the pathologic staging of endometrial carcinomas are covered with practical advice for the reporting pathologist. These include issues regarding the assessment of the depth of myometrial involvement (which may be rendered difficult due to a variety of factors), tumor involvement of adenomyosis, and assessment of cervical and uterine serosal involvement. Although not included in the FIGO staging system, the issue of lymphovascular space invasion (LVSI) is covered as this is of prognostic importance and there are multiple problems in the pathologic assessment of this. One important point is that tumors should not be upstaged based on the presence of LVSI alone without tissue involvement; for example, the presence of LVSI in the outer half of the myometrium or in cervical or adnexal vessels in a carcinoma with myoinvasion confined to the inner half of the myometrium is still FIGO stage IA. The issue of simultaneously occurring tumors of the endometrium and adnexa is also covered with advice on how to distinguish between synchronous independent and metastatic neoplasms of both endometrioid and nonendometrioid types. Recent molecular evidence showing that simultaneously occurring endometrioid carcinomas of the endometrium and ovary are clonal and thus probably represent metastatic disease from the endometrium to the ovary rather than synchronous independent neoplasms, as is widely assumed, is discussed.

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.

[Pertinence of the preoperative exploration in the evaluation of the risk of lymph node metastasis in endometrial cancer]

PURPOSE

To assess the relevance of MRI, endometrial biopsy and curettage in the diagnosis of endometrial cancer at high risk of lymph node metastasis.

PATIENTS AND METHODS

A retrospective study on continuous series of patients treated for endometrial cancer limited to the uterus between 2004 and 2008, results of preoperative evaluation of tumor stage using MRI, histological type and grade by endometrial curettage and biopsies were compared to final histological examination.

RESULTS

One hundred and sixty-nine patients were included in the study. Ninety (53.3%) had MRI, 112 (66.2%) curettage and 61 (36.6%) endometrial biopsy using Pipelle de Cornier. Sensibility (SN), specificity (SP), positive (PPV) and negative predictive values (NPV) of MRI, in the diagnosis of endometrial cancer at high risk of lymph nodes metastases were of 65.6%, 87.2%, 77.7%, 79.2%. For EB and curettage SN, SP, PPV and NPV were of 42.9%, 96.9%, 85%, 79.5%; 80.6%, 98.3%, 96.2% and 90.6% respectively. 37.8% of cancers diagnosed to be at low risk of lymph node metastasis were at high risk in definitive histologic examination.

DISCUSSION AND CONCLUSION

Preoperative evaluation by MRI, endometrial curettage and biopsy has good diagnostic value in the identification of endometrial cancer susceptible to benefit from lymphadenectomy. Underestimation, however, is encountered in approximately one third of cases.

Patterns of myoinvasion in endometrial adenocarcinoma: recognition and implications

Endometrial endometrioid adenocarcinoma (EEC) is the most common malignancy of the female genital tract, partly attributable to chronic estrogen exposure secondary to increased obesity rates. Tumor stage, which in most cases is based on depth of invasion (DOI), is of critical importance in determining if additional treatment is needed. However, the array of invasive morphologies within the spectrum of ECC can make the determination of DOI difficult. Several morphologic patterns of invasion have been described, including diffusely infiltrating irregular glands, "broad front" (or pushing border), adenoma malignum, adenomyosis-like, and microcystic, elongated, and fragmented glands. EEC may often contain a mixture of invasive patterns, which can further complicate evaluation of these common tumors. Recognition of these patterns may lead to more accurate staging, but perhaps more importantly, some patterns may be associated with adverse prognostic features. The purpose of this review is to highlight the various invasive patterns of EEC and note their unique pitfalls and prognostic implications in an effort to improve staging accuracy and treatment and follow-up for the thousands of women affected by this disease each year.

New developments in endocervical glandular lesions

McCluggage W G (2012) Histopathology New developments in endocervical glandular lesions There is evidence that the prevalence of premalignant and malignant endocervical glandular lesions is increasing in real as well as in apparent terms. In this review, new developments and selected controversial aspects of endocervical glandular lesions are covered, concentrating mainly on premalignant and malignant lesions. The terminology of premalignant endocervical glandular lesions is discussed with a comparison of the World Health Organization classification and the cervical glandular intraepithelial neoplasia (CGIN) system, which is in widespread use in the United Kingdom. Primary cervical adenocarcinomas comprise a heterogeneous group of different morphological types, and while it is known that the majority of these are associated with high-risk human papillomavirus (HPV), it has become clear in recent years that most of the more uncommon morphological types are unassociated with HPV, although they may sometimes be p16-positive. A spectrum of benign, premalignant and malignant cervical glandular lesions exhibiting gastric differentiation is now recognized; these include type A tunnel clusters, typical and atypical lobular endocervical glandular hyperplasia, adenoma malignum and gastric-type adenocarcinoma. The latter is a recently described variant of primary cervical adenocarcinoma which has a different morphological appearance to the usual endocervical type and which is probably associated with different patterns of spread and a worse prognosis. There is accumulating evidence that 'early invasive' cervical adenocarcinomas have an excellent prognosis and are suitable for conservative management. Immunohistochemical markers of value in the distinction between a primary cervical and endometrial adenocarcinoma are discussed. While it is well known that a panel of markers comprising oestrogen receptor (ER), vimentin, p16 and monoclonal carcinoembryonic antigen (CEA) is useful, several major pitfalls are pointed out and this panel of markers is predominantly of value in 'low-grade' adenocarcinomas. A related group of lesions, including cervical ectopic prostatic tissue and vaginal tubulosquamous polyp, are probably derived from para-urethral Skene's glands and may be positive with prostatic markers. Recent developments in cervical neuroendocrine neoplasms are discussed, as these are associated not uncommonly with a premalignant or malignant endocervical glandular lesion.

Diagnostic Accuracy of Magnetic Resonance Imaging in Endometrial Cancer

Objectives

The objectives of this study were to investigate the accuracy of magnetic resonance imaging (MRI) in predicting the depth of myometrial invasion in the preoperative assessment of women with endometrial cancer and to quantify the impact of MRI as an adjunct to predicting patients requiring full surgical staging.

Methods

This was a diagnostic accuracy study of prospective cases in conjunction with STARD guidelines using collected data from a tumor board within a cancer network. Consecutive series of all endometrial cancers in Northern Ireland over a 21-month period was discussed at the Gynaecological Oncology Multidisciplinary Team/tumor board meeting. This study concerns 183 women who met all the inclusion criteria. Main outcome measure was the correlation between the depth of myometrial invasion suggested by preoperative MRI study and the subsequent histopathological findings following examination of the hysterectomy specimen. Secondary end point was how MRI changed management of women who required surgery to be performed at a central cancer center.

Results

For the detection of outer-half myometrial invasion, overall sensitivity of MRI was 0.73 (95% confidence interval [CI], 0.59–0.83), and specificity was 0.83 (95% CI, 0.76–0.89). The positive predictive value was 0.63 (95% CI, 0.50–0.74), and negative predictive value was 0.89 (95% CI, 0.82–0.93). Positive likelihood ratio was 4.35 (95% CI, 2.87–6.61), and negative likelihood ratio was 0.33 (95% CI, 0.21–0.52). Magnetic resonance imaging improved the sensitivity and negative predictive value of endometrial biopsy alone in predicting women with endometrial cancer who require full surgical staging (0.73 vs 0.65 and 0.80 vs 0.78, respectively).

Conclusions

Preoperative pelvic MRI is a moderately sensitive and specific method of identifying invasion to the outer half of myometrium in endometrial cancer. Addition of MRI to preoperative assessment leads to improved preoperative assessment, triage, and treatment.

Atypical Endometrial Hyperplasia and Well Differentiated Endometrioid Adenocarcinoma of the Uterine Corpus

The distinction between atypical endometrial hyperplasia and well differentiated adenocarcinoma of the endometrium is one of the more difficult differential diagnoses in gynecologic pathology. Different pathologists apply different histologic criteria, often with different individual thresholds for atypical endometrial hyperplasia and grade 1 adenocarcinoma. While some classifications are based on a series of molecular genetic alterations (which may or may not translate into biologically or clinically relevant risk lesions), almost all current diagnostic criteria use a series of histologic features - usually a combination of architecture and cytology - for diagnosing atypical hyperplasia and adenocarcinoma. This article presents evidence-based histologic criteria for atypical endometrial hyperplasia and low grade endometrial carcinoma (both FIGO grade 1 and 2) with emphasis on common and not so common histologic mimics. Grade 3 endometrioid carcinoma is discussed in the Oliva and Soslow article in this publication.