Frequent KRAS mutation in complex mucinous epithelial lesions of the endometrium

Targeting KRAS in gynecological malignancies

Cervical, endometrial, and ovarian cancers stand prominently as the leading gynecological malignancies of the female reproductive system. The conventional therapeutic modalities for gynecological malignancies have predominantly encompassed surgery, chemotherapy, and radiotherapy. However, efficacy of these approaches remains limited in cases of relapse or drug resistance. KRAS is one of the most frequently mutated oncogenes in human cancers. The KRAS gene encodes a small guanosine triphosphatase protein that acts as a molecular switch for crucial intracellular signaling pathways. KRAS mutations are deeply involved in the occurrence and development of gynecological malignancies. The present review aims to expound upon the role of oncogenic KRAS as a biomarker, elucidating various therapeutic approaches under investigation targeting the KRAS pathway in gynecological tumors.

Genomic analysis of primary epithelial neoplasms of the seminal vesicle identifies a subset of mucinous cystic tumours driven by KRAS mutations

BACKGROUND

Carcinomas of the seminal vesicle are exceedingly rare, with a limited number of cases described in the literature. Reported cases span a relatively wide morphological spectrum, and their genomic features remain unexplored.

DESIGN

In this study, we interrogated five primary epithelial neoplasms of the seminal vesicle using a targeted DNA sequencing platform (OncoPanel, 447 genes).

RESULTS

The tumours included one adenocarcinoma with intestinal phenotype presenting after external beam radiation (for prostatic adenocarcinoma), one carcinoma with Müllerian-type clear cell phenotype, two mucinous tumours resembling low-grade mucinous neoplasms of the appendix (LAMN) and one mucinous cystadenoma. The post-radiation mucinous adenocarcinoma had genomic findings consistent with bi-allelic inactivation of TP53, as well as multiple copy-number changes with regional and chromosomal arm-level copy-number losses. The Müllerian-type clear cell carcinoma exhibited a complex copy-number profile with numerous regional and arm-level copy-number changes, as well as focal amplification events, including copy-number gain of 8q and amplification of a region within 20q13. Both low-grade mucinous tumours resembling LAMN harboured hot-spot gain-of-function KRAS variants (p.G12V and p.G13D) as the only genomic alteration. No genomic alterations were detected inthe lesion diagnosed as mucinous cystadenoma.

CONCLUSION

Our results suggest that primary low-grade mucinous neoplasms of the seminal vesicle may represent a distinct entity equivalent to appendiceal counterparts, driven by gain-of-function variants of RAS GTPases. The remaining tumours showed genomic features that closely resembled those of neoplasms with comparable phenotypes and/or biological characteristics arising in other sites, suggesting that they could be managed similarly, with special considerations related to their anatomical location.

Utility of a PAX2, PTEN, and β-catenin Panel in the Diagnosis of Atypical Hyperplasia/Endometrioid Intraepithelial Neoplasia in Endometrial Polyps

The diagnosis of atypical hyperplasia/endometrioid intraepithelial neoplasm (AH/EIN) within endometrial polyps (EMPs) often poses a diagnostic conundrum. Our previous studies demonstrated that a panel of immunohistochemical (IHC) markers consisting of PAX2, PTEN, and β-catenin can be effectively utilized for the identification of AH/EIN. A total of 105 AH/EIN within EMP were analyzed using the 3-marker panel. We also evaluated these cases for the presence of morules. Benign EMP (n=90) and AH/EIN unassociated with polyp (n=111) served as controls. Aberrant expression of PAX2, PTEN, or β-catenin was observed in AH/EIN in EMP in 64.8%, 39.0%, and 61.9% of cases, respectively. At least 1 IHC marker was abnormal in 92.4% of cases. Overall, 60% of AH/EIN in EMP demonstrated abnormal results for≥2 IHC markers. The prevalence of PAX2 aberrancy was significantly lower in AH/EIN in EMP than in nonpolyp AH/EIN (64.8% vs. 81.1%, P =0.007), but higher than in benign EMP (64.8% vs. 14.4%, P <0.00001). The prevalence of β-catenin aberrancy was significantly higher in AH/EIN in EMP than in nonpolyp AH/EIN (61.9% vs. 47.7%, P =0.037). All control benign EMP demonstrated normal expression of PTEN and β-catenin. Morules were present in 38.1% of AH/EIN in EMP versus 24.3% in nonpolyp AH/EIN, and absent in benign EMP. A strong positive association was found between β-catenin and morules (Φ=0.64). Overall, 90% cases of atypical polypoid adenomyoma (n=6) and mucinous papillary proliferation (n=4) showed IHC marker aberrancy. In conclusion, the 3-marker IHC panel (PAX2, PTEN, and β-catenin) is (1) a useful tool in the diagnosis of AH/EIN in EMP; (2) PAX2 loss should be interpreted with caution and in combination with morphology and other markers.

PTEN mutation predicts unfavorable fertility preserving treatment outcome in the young patients with endometrioid endometrial cancer and atypical hyperplasia

OBJECTIVE

This study aimed to investigate the impact of molecular classification and PTEN, KRAS and PIK3CA gene mutation on the outcome of fertility-preserving treatment in the patients with endometrioid endometrial cancer (EEC) and endometrial atypical hyperplasia (EAH).

METHODS

This is a single-center retrospective study. A total of 135 patients with EEC and EAH receiving fertility-preserving treatment and molecular classification were reviewed. The distribution of the four types of molecular classification was described. The impact of non-specific molecular profile (NSMP), mismatch repair-deficiency (MMRd), and PTEN, KRAS and PIK3CA gene mutation on the outcome of fertility-preserving treatment was analyzed.

RESULTS

Of the patients analyzed, 86.7% (117/136) were classified as having NSMP; 14 (10.4%), MMRd; 1 (0.7%), POLEmut EAH; and 3 (2.2%), p53abn EEC. The patients having NSMP and MMRd achieved similar 16-, 32-, and 48-week complete response rates. The patients harboring tier I and tier II PTEN mutations (PTENmut-Clin) achieved lower cumulative 32-week CR rates than those with PTEN-others (without PTENmut-Clin) (22/47, 46.8% vs. 50/74, 67.6%; p=0.023; odds ratio=0.422; 95% confidence interval [CI]=0.199-0.896). Insulin-resistance (hazard ratio [HR]=0.435; 95% CI=0.269-0.702; p=0.001) and PTENmut-Clin (HR=0.535; 95% CI=0.324-0.885; p=0.015) were independent negative predictors for lower 32-week CR rates.

CONCLUSION

PTENmut-Clin is an independent risk factor for unfavorable fertility-preserving treatment outcomes in the patients with EEC and EAH. The patients with MMRd receiving fertility-preserving treatment achieved outcomes similar to those of the patients with NSMP. The molecular profiles might guide fertility-preserving treatment in the prognosis and clinical decisions.

Estrogen/Progesterone Receptor Loss, CTNNB1 and KRAS Mutations Are Associated With Local Recurrence or Distant Metastasis in Low-Grade Endometrial Endometrioid Carcinoma

A subset of endometrial endometrioid carcinomas (EECs) with low-grade histology recur with poor outcomes. Published evidence suggests that poor outcomes may be associated with loss of expression of ER-alpha (ER-α) as well as with β-Catenin-1 ( CTNNB1 ) and Kirsten rat sarcoma viral oncogene homolog ( KRAS ) mutations. This study reports on institutional experience with the incidence of recurrence in low-grade EEC and their association with CTNNB1 and KRAS mutations as well as estrogen/progesterone receptor (ER/PR) expression. Forty-eight (8.5%) out of 568 cases of low-grade EEC with biopsy-proven recurrence were identified; and were analyzed by immunohistochemistry for ER, PR, p53, MMR protein, and mutation analysis for exon 3 of the CTNNB1 and exon 2 of KRAS in relation to recurrence type, local or distant metastasis/recurrence. Twenty-three patients (4%) developed local, and 25 patients (4.4%) developed distant metastases/recurrence. Decreased expression or loss of ER/PR was found in 17/44 (38.6%) patients with recurrence. Eighty-four percent of patients with low-grade EEC and local recurrence had CTNNB1 mutations. Seventy-three percent of patients with distant metastasis/recurrence had KRAS mutations. The association of these mutations with the type of recurrence was statistically significant for both. Five cases with the morphology of low-grade EEC were reclassified as mesonephric-like carcinoma and were universally characterized by distant metastasis/recurrence, loss of ER/PR expression, large tumor size, absence of CTNNB1 mutations, and the presence of KRAS mutations. In low-grade EEC, CTNNB1 and KRAS mutations are associated with local recurrence and distant metastasis/recurrence, respectively, suggesting that these 2 different progression types may be conditioned by tumor genotype. ER/PR immunohistochemistry may be helpful in identifying poor performers in low-grade EEC. Furthermore, identification of the decreased expression or loss of ER/PR in tumors with low-grade histology should prompt consideration of mesonephric-like carcinoma, which is a more aggressive tumor than the low-grade EEC. KRAS mutations were associated with distant metastasis/recurrence in tumors with and without mesonephric-like phenotype.

Mucinous Proliferations of the Uterine Corpus: Comprehensive Appraisal of an Evolving Spectrum of Neoplasms

A variety of endometrial lesions may contain mucinous cells. Herein, the author reviews the literature on the classification and clinicopathologic significance of uterine corpus proliferations with a significant mucinous component, assesses the 2020 World Health Organization classification of such lesions, and presents a diagnostic framework. The key epithelial mucinous lesions include mucinous metaplasia, atypical mucinous glandular proliferation and mucinous carcinoma. Each of these categories are classifiable into "usual" and gastrointestinal subtypes, the latter being indicative of intestinal (presence of goblet cells) and/or gastric-type (abundant, pale eosinophilic or clear cytoplasm and well-defined cell borders) morphology. It has been proposed that at least focal expression of gastrointestinal immunohistochemical markers be required for all gastrointestinal type lesions, and for gastrointestinal type atypical mucinous glandular proliferation and carcinoma, minimality or absence of estrogen receptor expression, and the absence of an endometrioid component. Mucinous carcinomas of the usual type, in which >50% of the tumor is comprised of a mucinous component, are the most common. Morphologic subtypes include mucinous carcinoma with microglandular features and mucinous carcinoma with signet rings (signet ring carcinoma). Endometrioid carcinomas with a less than a 50% mucinous component are classified as endometrioid carcinoma with mucinous differentiation. Several studies have directly compared endometrioid and mucinous carcinomas, the latter presumably of the usual type, with respect to patient outcomes after treatment. All have found no difference in overall and disease free survival between these groups. However, three major studies have found mucinous carcinomas to be associated with a higher risk of lymph node metastases. Nineteen cases of mucinous carcinoma of the gastrointestinal type have been reported, and the limited data on their follow-up after primary treatment suggests that this subtype is more clinically aggressive and should accordingly be classified separately from mucinous carcinomas of the usual type. The morphologic spectrum of mucinous carcinoma of the gastrointestinal type is unclear and continues to evolve. Mucinous change, which may sometimes be extensive, may also be associated with papillary proliferation of the endometrium, adenomyoma of the endocervical type, atypical, and typical adenomyomas. In a curettage or biopsy, intestinal type mucinous epithelium may be indicative of any of the gastrointestinal lesions mentioned above, but may also represent samplings of uterine teratomas, yolk sac tumors, genital and extragenital adenocarcinomas with intestinal differentiation, or low-grade appendiceal mucinous neoplasms that secondarily involve the endometrium.

A 2-tier subdivision of papillary proliferations of the endometrium (PPE) only emphasizing the complexity of papillae precisely predicts the neoplastic risk and reflects the neoplasia-related molecular characteristics-a single-centered analysis of 207 cases

Papillary proliferation of the endometrium (PPE) is subdivided based on the complexity of the papillae and the proliferation of lesions, and the complex group is considered to have an increased risk of concurrent/subsequent endometrial neoplasia. However, the current subdivision criteria fail to prove the equivalence of the quantity of simple papillae and structural complexity. In this study, we divided PPE of 207 cases from 2014 to 2022 into 3 groups according to structural complexity and proliferation degrees: Group 1 equaled to the simple PPE with a simple papillary structure and typical localized proliferation; group 2 had the simple structure similar to group 1 but occupy over 50% of the endometrial polyp or > 2 lesions in the surface of nonpolypoid endometrium; group 3 had the truly complex branching papillae despite of its proportion. Group 3 was implicated with significantly more concurrent endometrial neoplasia (EAH and carcinoma) compared with groups 1 and 2 (P < 0.01), while no difference was found between groups 1 and 2. In 128 cases with no concurrent endometrial abnormalities in the initial biopsy or curettage specimens, 4 cases presented endometrial neoplasia (3 carcinoma and 1 atypical hyperplasia) in the subsequent specimens, all of which presented PPE of group 3 but not group 1 or 2 in the prior tissues (P < 0.01). The immunochemistry of 83 cases showed similar expressions of ER, PTEN, ARID1A, PTEN, p16, β-catenin, and p53 between PPE and the surrounding normal endometrium. Nearly 100% of PPE cases lost expressions of PR. A total of 2/83 cases showing PAX2 expression were all in the group 3 and correlated with endometrial neoplasia (2/17, 11.76%, P < 0.05). 76/83 (91.57%) of PPE lesions had KRAS mutations, and the distributions of which were similar among 3 groups. The frequency of mucinous metaplasia was significantly higher in the PPE lesions with KRAS mutations (72/74, 97.30%, P < 0.01). Group 3 showed higher frequency of single KRAS mutations compared with the combination of groups 1 and 2 (P < 0.01). Finally, the concordance of KRAS mutation profiles between PPE and endometrial neoplasia was significantly higher in group 3 than either group 1 or 2 (P < 0.01), while no difference was found between group 1 and 2. Thus, a new 2-tier subdivision system only emphasizing the complexity of papillae is recommended, which might precisely predict the risk of endometrial neoplasia and neoplasia-related molecular characteristics.

Microglandular hyperplasia-like mucinous adenocarcinoma of the endometrium: A rare case report

BACKGROUND

Microglandular hyperplasia (MGH) is a proliferation of endocervical glands, related to estrogen stimulation, mainly occurring in the reproductive age group. The differential diagnosis includes endometrial adenocarcinoma with MGH-like pattern (MGA), a distinction that may be particularly problematic in curettage specimen.

CASE SUMMARY

A 57-year-old, postmenopausal woman was admitted in our hospital for surgical treatment. She had been diagnosed with a uterine leiomyoma, after complaints of irregular vaginal bleeding. She underwent dilatation and curettage (D&C) and subsequent total abdominal hysterectomy with bilateral salpingo-oophorectomy. D&C were compatible with MGA. Histologically, a proliferation of small glands, without intervening stroma, with mucin production, accumulation of neutrophils in the gland lumen and stroma, mild nuclear atypia and rare mitoses, were seen. In the hysterectomy specimen, the endometrium was thickened, but without apparent tumor formation. On microscopic examination, a residual similar adenocarcinoma was seen in the isthmus and more conventional-of endometrioid and mucinous type, in the rest of the endometrium.

CONCLUSION

MGH-like proliferation with mild cytologic atypia, detected in the endometrial curettage specimen of a postmenopausal woman, should alert pathologists for MGA of the endometrium. VIM, p16, PAX-2, CD10 and CD34 may help in the differential diagnosis.

Endometrial Metaplastic/Reactive Changes Coexistent with Endometrial Hyperplasia and Carcinoma: A Morphological and Immunohistochemical Study

The aim of this study was to assess the relationship between endometrial metaplastic/reactive changes (EMRCs) and endometrial neoplastic lesions. Twenty cases of “simple” (without architecture complexity) EMRCs coexistent with endometrial malignant/premalignant lesions, twenty cases of neoplasia-unassociated EMRCs, and eight cases of complex metaplastic lesions were assessed by immunohistochemistry. EMRCs coexisted with endometrioid carcinoma (n = 12), atypical endometrial hyperplasia (n = 3), serous carcinoma (n = 2), and clear cell carcinoma (n = 3). Neoplasia-associated EMRCs showed a mean Ki67 labeling index of 12.6% (range 0–30%); with nuclear atypia in 16/20 (80%) cases; diffuse p16 expression in 15/20 (75%) cases; and heterogeneous ER, PR, and vimentin expression. Compared to the associated neoplasia, EMRCs showed a lower Ki67 expression (p < 0.001) and higher p16 expression (p < 0.001). No EMRC case showed mitotic activity, PTEN loss, MMR deficiency, nuclear β-catenin, p53-mutant pattern, Napsin A, or AMACR expression. No significant differences were found between neoplasia-associated and neoplasia-unassociated EMRCs. Complex metaplastic lesions showed a lower Ki67 expression than EMRCs (p = 0.044) and PTEN loss in 5/8 cases, even in the absence of nuclear atypia. In conclusion, neoplasia-associated simple EMRCs may show evident atypia and a worrisome immunophenotype, but no data support their involvement in endometrial carcinogenesis. Architectural complexity appears as a crucial factor to identify precancerous lesions.

The Advance and Correlation of KRAS Mutation With the Fertility-Preservation Treatment of Endometrial Cancer in the Background of Molecular Classification Application

The annually increasing incidence of endometrial cancer in younger women has created a growing demand for fertility preservation. However, the diverse therapeutic efficacy among patients under the same histological subtype and the same tumor grade suggests the potential interference of the innate molecular characteristics. The molecular classification has now been applied in clinical practice and might help to stratify the endometrial cancer patients and individualize the therapy, but the candidates for the fertility-spared treatment are most likely to be subdivided in the subgroup lacking the specific signature. KRAS mutation has been linked to the malignant transition of the endometrium, while its role in molecular classification and fertility preservation is vague. Here, we mainly review the advance of molecular classification and the role of KRAS in endometrial cancer, as well as their correlation with fertility-preservation treatment.

Emerging relationships between papillary proliferation of the endometrium and endometrial carcinoma: evidence from an immunohistochemical and molecular analysis

Papillary proliferation of the endometrium (PPE) is an uncommon lesion that frequently shows mucinous metaplasia. PPE occasionally has concurrent or preceding endometrial hyperplasia and carcinomas, but there is little molecular evidence to support the relationships between PPEs and endometrial neoplasia. In this study, we analyzed the clinicopathological and immunohistochemical features in 30 PPEs (22 simple PPEs and 8 complex papillary hyperplasia (CPH)). Hotspot mutations of KRAS, PI3KCA, AKT1, PTEN (exons 3, 5, and 7), and ARID1A (exons 1 and 14) were detected by pyrosequencing or bidirectional Sanger sequencing. We found that endometrial hyperplasia and carcinoma were more common in CPHs (4/6, 66.7%) than in simple PPEs (4/21, 19.0%) (p < 0.05). Compared with the adjacent normal endometrium, PPEs frequently showed loss of PAX2 (56.7%) and PTEN (10%) expression, diffuse p16 expression (36.7%), decreased PR expression (84.3%), and lower Ki67 labeling index (median 1%, range 1-15%). Simple PPEs and CPHs had similar immunohistochemical features (p > 0.05). KRAS mutations were identified in 14 PPEs and 1 concurrent endometrial carcinoma. The prevalence of KRAS mutations was not statistically different between simple PPEs (10/21, 45.5%) and CPHs (4/8, 50%) (p > 0.05), but was higher in PPEs displaying mucinous metaplasia (12/24, 50%) than in those without (2/6, 33.3%) (p < 0.05). One simple PPE with a KRAS mutation had an AKT1 mutation. No PPEs demonstrated mutations in PI3KCA, PTEN, and ARID1A. In conclusion, both simple PPE and CPH share some common molecular alterations with endometrial neoplasia, in which, KRAS mutations might be a driver.

Benign and Premalignant Lesions of the Endometrium

In this review, we highlight the benign and premalignant lesions of the endometrium that the pathologist may encounter in daily practice. We begin by detailing our current understanding of excess estrogen in the progression of endometrial neoplasia. We outline the currently accepted terminology to be used when evaluating proliferative endometrial lesions, while highlighting their key features. Attention is then turned to the molecular underpinnings of neoplastic progression and how this can be exploited with immunohistochemical stains when appropriate. Finally, we discuss types of metaplasia and their associations, including so-called papillary proliferations of the endometrium.

Genomic Comparison of Endometrioid Endometrial Carcinoma and Its Precancerous Lesions in Chinese Patients by High-Depth Next Generation Sequencing

Endometrial intraepithelial neoplasia (EIN), also known as endometrial atypical hyperplasia (EAH) is believed to be the precursor lesion of endometrioid endometrial carcinoma (EEC). Many genetic factors play important roles in the process of carcinogenesis, however, the key genetic alterations from dysplasia to endometrial cancer remains poorly understood. Germline mutations in Lynch syndrome genes are associated with hereditary endometrial carcinoma. The role of other cancer susceptibility genes is unclear. The aim of this study was to investigate the genomic alterations of premalignant endometrial lesion and EEC, and to determine the prevalence of cancer predisposition gene mutations in an unselected endometrial carcinoma patient cohort. Here, we applied a comprehensive cancer gene panel (363 cancer-related genes) to capture the exomes of cancer-related genes. Samples were collected from 79 patients with EEC and 36 patients with EIN. Our results demonstrate that EIN harbors most of the driver events reported in EEC and for the first time we reported a high frequency of the amplification of VEGFB gene in endometrial cancer. Moreover, we identified four novel candidate cancer-associated genes (CTCF, ARHGAP35, NF1, and KDR) which may be crucial in the carcinogenesis of EEC. In addition, we identified 2 patients who had a deleterious germline mutation in Lynch syndrome genes (MLH1 and MLH2), and another 8 patients harbored germline mutations of 6 non-Lynch syndrome genes (MUTYH, GALNT12, POLE, MPL, ATM, and ERCC4) which may be associated with endometrial cancer. Larger series will have to be investigated to assess the risks and the proportion of endometrial cancers attributable to other genes.

Detection of MAPK/ERK pathway proteins and KRAS mutations in adenomatoid odontogenic tumors

OBJECTIVE

This study aimed to assess the frequency of KRAS mutation and its association with the presence of the MAPK/ERK signaling pathway proteins in adenomatoid odontogenic tumors.

STUDY DESIGN

Paraffin-embedded tissue samples from nine cases of adenomatoid odontogenic tumor were used. Genomic DNA was extracted from each sample; in one case, genetic mutations in 50 cancer-associated genes were examined by next-generation sequencing. Hotspot mutations in the RAS family were analyzed by Luminex assay using the remaining eight cases. Subsequently, immunohistochemistry for KRAS, CRAF, BRAF, EGFR, ERK, MEK, and BRAFV600E was performed.

RESULTS

A KRAS G12D missense mutation was detected in the DNA sequence of the tumor cells, but it was not detected in the stromal tissue. KRAS G12V and KRAS G12R mutations were detected in two and four cases, respectively. For immunohistochemistry, all the cases were EGFR, KRAS, BRAF, CRAF positive, one case was ERK negative,and one case was MEK and ERK negative, all the other remaining cases were MEK and ERK positive.

CONCLUSION

KRAS mutation at codon 12 and the presence of MAPK/ERK pathway proteins were detected suggesting their association with tumorigenesis of adenomatoid odontogenic tumors.

Endometrial Adenocarcinomas With Significant Mucinous Differentiation: A Characterization of Intratumoral Heterogeneity of KRAS Mutations in Mucinous and Endometrioid Histologic Components

OBJECTIVE

KRAS mutations are frequently seen in malignancies with mucinous morphology. In our previous study, mucinous endometrial carcinomas were associated with a significantly higher frequency of KRAS mutations as compared with matched conventional endometrioid carcinomas. This study expands our previous report by exploring possible intratumoral heterogeneity for KRAS gene mutations in the mucinous components of mucinous carcinomas (MCs) and endometrioid carcinomas with significant mucinous differentiation (ECSMD) versus their associated "usual" endometrioid components.

MATERIALS AND METHODS

KRAS-positive cases from our previous report were studied, including 10 MCs and 10 ECSMDs. The specimens were microscopically dissected to separately isolate morphologically mucinous and endometrioid components. Direct DNA sequencing for KRAS mutations at codons 12 and 13 using capillary electrophoresis were performed.

RESULTS

KRAS mutations were detected in the endometrioid components of 8 (80%) of 10 MCs and 3 (30%) of 10 ECSMDs. The endometrioid component of the ECSMD group was less frequently associated with KRAS mutation than the endometrioid component of the MC group, even when the mucinous component of the same tumor contained a mutation; the difference is statistically significant (P < 0.05).

CONCLUSIONS

Our current study shows that intratumoral heterogeneity for KRAS gene mutation was associated with ECSMD, but less frequently with MC. It is possible that when the mucinous component predominates, qualifying for an MC, KRAS mutations appear to be widespread, irrespective of the mucinous or nonmucinous differentiation of the tumor cells. The findings suggest that multiple samples for KRAS tests may be useful, especially in endometrioid carcinoma with significant mucinous differentiation.

Benign endometrial proliferations mimicking malignancies: a review of problematic entities in small biopsy specimens

Benign proliferations that mimic malignancies are commonly encountered during the course of assessment of small and fragmented endometrial samples. Although benign, endometrial epithelial metaplasias often coexist with premalignant or malignant lesions causing diagnostic confusion. The difficulty with mucinous metaplasia lies in its distinction from atypical mucinous glandular proliferations and mucinous carcinomas, which are associated with significant interobserver variability. Papillary proliferation of the endometrium is commonly associated with hormonal drugs and endometrial polyps and is characterised by papillae with fibrovascular cores covered by epithelial cells without cytologic atypia. They are classified into simple or complex papillary proliferations depending on the architectural complexity and extent of proliferation. Complex papillary proliferations are associated with a high risk of concurrent or subsequent hyperplasia with atypia/carcinoma. Papillary proliferations may have coexisting epithelial metaplasias and, most commonly, mucinous metaplasia and syncytial papillary change. Those with striking mucinous metaplasia overlap morphologically with papillary mucinous metaplasia. The latter has been proposed as a precursor of endometrial mucinous carcinoma. Misinterpreting the Arias-Stella reaction as a malignant or premalignant lesion is more likely to occur if the pathologist is unaware that the patient is pregnant or on hormonal drugs. Endometrial hyperplasia with secretory changes may occasionally be difficult to distinguish from the torturous and crowded glands of a late secretory endometrium. Endometrial polyps may have abnormal features that can be misinterpreted as endometrial hyperplasia or Mullerian adenosarcoma. Awareness of these benign endometrial proliferations and their common association with hormonal medication or altered endogenous hormonal levels will help prevent the over-diagnosis of premalignant and malignant lesions.

The diagnosis of mucinous lesions in endometrial samplings by gynaecological pathologists: an analysis of diagnostic reproducibility

The purpose of this study is to assess the reproducibility among gynaecological pathologists in their diagnosis of mucinous alterations in endometrial sampling specimens. Twenty-six cases were independently reviewed by four experienced gynaecological pathologists from four academic medical centres. Pathologists were asked to classify each case into one of four groups, including three World Health Organization (WHO)-recognised categories: (1) mucinous metaplasia; (2) atypical mucinous glandular proliferation; (3) carcinoma; and (4) 'other' (absence of a true mucinous alteration and/or an alteration of non-endometrial origin). The overall reproducibility was 'fair' (κ = 0.39). In an analytical scenario that established three clinically significant groups ('benign/non-neoplastic', 'atypical', and 'carcinoma') by redistributing all group 4 responses, the resultant kappa improved to 0.51 (moderate reproducibility). In another analysis with only two categories-'benign/non-neoplastic' versus 'atypical/carcinoma'-reproducibility was similarly moderate (κ = 0.46). However, with one exception, all cases that were ultimately diagnosed as carcinoma in a follow-up hysterectomy specimen, were classified as atypical or carcinoma in the preceding sampling. For 11 cases that were classified as either 'carcinoma' or 'atypical' by all observers, there was moderate reproducibility (κ = 0.53) in making that distinction, and none of a wide array of morphological features were found to significantly distinguish between these two categories. For five cases that all observers classified as either mucinous metaplasia or benign endocervix, reproducibility was substantial (κ = 0.67). In summary, gynaecological pathologists show moderate reproducibility in categorising mucinous alterations in endometrial sampling specimens as benign, atypical, or carcinomatous. They accurately classify as at least 'atypical' those cases that are ultimately diagnosed as carcinoma in the subsequent resection. Our findings suggest that there are indeed some mucinous alterations which have features that do not allow for reproducible assignment by pathologists into the WHO-recognised categories. In this subset of cases, there may be a need for better-defined diagnostic criteria and/or extra-morphological diagnostic tools.

Molecular Pathology: Predictive, Prognostic, and Diagnostic Markers in Uterine Tumors

This article focuses on the diagnostic, prognostic, and predictive molecular biomarkers in uterine malignancies, in the context of morphologic diagnoses. The histologic classification of endometrial carcinomas is reviewed first, followed by the description and molecular classification of endometrial epithelial malignancies in the context of histologic classification. Taken together, the molecular and histologic classifications help clinicians to approach troublesome areas encountered in clinical practice and evaluate the utility of molecular alterations in the diagnosis and subclassification of endometrial carcinomas. Putative prognostic markers are reviewed. The use of molecular alterations and surrogate immunohistochemistry as prognostic and predictive markers is also discussed.

Atypical mucinous glandular proliferations in endometrial samplings: follow-up and other clinicopathological findings in 41 cases

The 2014 World Health Organization classification calls for endometrial mucinous proliferations that display "confluent or cribriform architecture with even minimal atypia" in sampling specimens to be classified as carcinoma, and others whose features are not diagnostic of carcinoma to be categorized as atypical mucinous glandular proliferations (AMGPs). Herein, we evaluate follow-up findings in 41 cases that were classified as AMGP from our files. The average patient age was 46years (range, 37-59 years). Postbiopsy follow-up duration ranged from 15 to 109weeks (mean, 40 weeks). There was no follow-up resection in 12 patients (9 with repeat biopsies, all 9 with no clinical evidence of disease, mean follow-up of 43weeks), and 29 patients underwent a hysterectomy an average of 2.4months after the index biopsy. The distribution of pathologic findings in the uteri was as follows: no residual AMGP or carcinoma (5/29; 17%), AMGP (11/29; 38%), and adenocarcinoma (13/29; 45%). All adenocarcinomas were grade I and stage I, and histotypes were endometrioid (n=8), mucinous (n=3), and endometrioid with mucinous differentiation (n=2). Only 3 (23%) carcinomas were myoinvasive, of which 1 case, a mucinous carcinoma with a 40% endometrioid component, showed greater than 50% myometrial invasion. None of a wide array of morphologic features was significantly associated with a hysterectomy diagnosis of carcinoma (versus AMGP) on univariate analyses. In conclusion, our cohort of AMGP represents a biologically variable spectrum of lesions that includes mucinous hyperplastic proliferations as well as endometrioid and mucinous adenocarcinomas that are occasionally myoinvasive. Morphologic features that optimally stratified AMGP cases into clinically relevant subgroups were not identified.

KRAS Mutations in Mucinous Lesions of the Uterus

OBJECTIVES

The current study examined the KRAS mutation status in a spectrum of mucinous lesions of the uterus, including mucinous metaplasia (MM), atypical mucinous proliferation (AMP), endocervical mucosa, and microglandular hyperplasia (MGH).

METHODS

Thirty-nine cases, including 15 AMPs, nine MMs, nine MGHs, and six normal endocervical mucosas, were selected from the departmental archive. All AMP cases with follow-up biopsies or hysterectomies were reviewed. Genomic DNA was extracted from formalin-fixed, paraffin-embedded tissue and KRAS codons 12 and 13 sequence analyzed.

RESULTS

KRAS codon 12 and 13 mutations were detected in 10 (67%) of the 15 AMP cases. No KRAS mutations were identified in MMs, MGHs, and endocervical mucosas (P = .002, AMP vs MM or MGH, Fisher exact test). Most women with AMP were postmenopausal (13/15 [86.7%]) and presented with dysfunctional uterine bleeding. Among the 10 cases of AMP harboring KRAS mutations, six (60%) cases were subsequently diagnosed with carcinoma, one with atypical complex hyperplasia, and two with AMP within endometrial polyps.

CONCLUSIONS

The results suggest a possible association between KRAS mutations and mucinous differentiation in endometrial carcinogenesis. KRAS status can help in assessing benign from precursor or malignant mucinous lesions as well as differentiate endometrial lesions from those of cervical origin.

Direct correlation between double K-RAS mutation and mucinous carcinoma. A case report

Mutations at the K-RAS locus in colon cancer cells are frequently associated with lack of responsiveness to therapy with EGFR inhibitors, as a consequence of the activation of Ras-dependent intracellular signals. Here we report a colon cancer case carrying a novel combination of K-RAS mutations involving codon 13 (Gly to Asp) and codon 19 (Leu to Phe), on separate alleles. The double mutation was restricted to tumor cells bearing a mucinous-like phenotype.

KRAS mutation testing in clinical practice

Activating mutation of KRAS plays a significant role in the pathogenesis of common human malignancies and molecular testing of KRAS mutation has emerged as an essential biomarker in the current practice of clinical oncology. The presence of KRAS mutation is generally associated with clinical aggressiveness of the cancer and reduced survival of the patient. Therapeutically, KRAS mutation testing has maximum utility in stratifying metastatic colorectal carcinoma and lung cancer patients for treatment with targeted therapy. Diagnostically, KRAS mutation testing is useful in the workup of pancreaticobiliary and thyroid cancers, particularly using cytological specimens. In the era of precision medicine, the role of KRAS mutation testing is poised to expand, likely in a setting of combinatorial therapeutic strategy and requiring additional mutation testing of its upstream and/or downstream effectors.