Morules in endometrioid proliferations of the uterus and ovary consistently express the intestinal transcription factor CDX2

Endometrioid Squamous Proliferations of the Endometrium Express Alpha-Methylacyl-CoA Racemase (P504s)

Squamous morular metaplasia is closely associated with endometrioid proliferative lesions such as endometrial intraepithelial neoplasia, whereas endometrioid adenocarcinoma may also demonstrate squamous differentiation (morular or nonmorular). Alpha-methylacyl-CoA racemase (AMACR; P504s) is an immunohistochemistry marker expressed in many tumors, including prostate adenocarcinoma, renal cell carcinoma, and in a subset of gynecologic carcinomas, predominantly of clear cell histology. In small biopsy samples, the distinction between cervical high-grade squamous intraepithelial lesions (HSILs) involving endocervical glands from endometrioid squamous proliferations can be challenging, given their anatomic vicinity and some degree of morphologic overlap. Following the observation of AMACR positivity by immunohistochemistry within squamous morules in an index case, 35 endometrial samples containing squamous morular metaplasia (25) and nonmorular squamous metaplasia (10), and 32 cases of cervical HSIL involving endocervical glands were stained with AMACR. The endometrial cohort consisted of 2 benign anovulatory endometrium, 7 endometrial polyps, 7 endometrial intraepithelial neoplasia, 4 atypical polypoid adenomyomas, and 15 endometrioid adenocarcinomas. Positive cases were scored as diffuse (≥50%) or focal (<50%). AMACR staining was present in 96.7% of endometrial squamous lesions, including 14 (93.3%) of endometrioid carcinomas, and in all cases of endometrial intraepithelial neoplasia, endometrial polyps, atypical polypoid adenomyomas, and anovulatory endometrium with squamous morular metaplasia or nonmorular squamous metaplasia. In comparison, only 2 cases (5.8%) of cervical HSIL demonstrated positivity for AMACR. In conclusion, AMACR can reliably differentiate the cervical versus endometrial origin of squamous lesions in small biopsy specimens.

High-grade Serous Carcinoma can Show Squamoid Morphology Mimicking True Squamous Differentiation

Tubo-ovarian high-grade serous carcinoma (HG-SC) and ovarian endometrioid carcinoma (EC) can show overlapping morphologic features, such as glandular and solid patterns. The differential diagnosis of these subtypes is thus sometimes difficult. The existence of "squamous differentiation" tends to lead to a diagnosis of EC rather than HG-SC. We noticed that HG-SC can contain a "squamoid component," but its nature has been poorly investigated. This study was thus established to clarify the nature of this "squamoid component" in HG-SC by investigating its frequency and immunohistochemical features. We reviewed hematoxylin and eosin-stained slides of 237 primary untreated cases of tubo-ovarian HG-SC and identified 16 cases (6.7%) of HG-SC with "squamoid component." An immunohistochemical staining panel (CK5/6, CK14, CK903, p40, p63, WT1, ER, and PgR) was used to analyze all of these 16 cases. We also selected 14 cases of ovarian EC with "squamous differentiation" as a control. The "squamoid component" in HG-SC was completely p40-negative and showed significantly lower expression of CK5/6, CK14, CK903, and p63 than the "squamous differentiation" in EC. The immunophenotype of the "squamoid component" in HG-SC was concordant with the conventional HG-SC component (WT1-positive/ER-positive). Furthermore, all 16 tumors were confirmed to be truly "HG-SC" by the findings of aberrant p53 staining pattern and/or WT1/p16 positivity, and the lack of mismatch repair deficiency and POLE mutation. In conclusion, HG-SC can on rare occasions show a "squamoid component" mimicking "squamous differentiation." However, the "squamoid component" in HG-SC does not represent true "squamous differentiation." The "squamoid component" is one part of the morphologic spectrum of HG-SC, which should be interpreted carefully for the differential diagnosis of HG-SC and EC. An immunohistochemical panel including p40, p53, p16, and WT1 is a useful adjunct to achieve a correct diagnosis.

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.

Pancreatoblastoma in Elderly Adults: Report of Two Patients

Introduction. Pancreatoblastoma is a rare malignant epithelial neoplasm of the pancreas, which often shows multiple lines of differentiation, but is defined by neoplastic cells with acinar differentiation and characteristic squamoid nests. Pediatric patients are most commonly affected, and although a subset is known to occur in adults, the diagnosis is rarely considered in elderly adults. Methods. The clinicopathologic features of two cases of pancreatoblastoma in elderly patients were examined. Results. Two patients (age 80 and 81 years) presented with pancreatoblastoma, including one with early-stage pancreatic disease and one with liver metastasis. Biopsies and one pancreatic resection specimen showed characteristic histomorphologic features, including prominent acinar differentiation and abundant squamoid nests. Both cases had complete loss of SMAD4 (DPC4) immunolabeling. Next generation sequencing was performed on one case and revealed copy number loss of chromosome 11p and 9p21 (CDKN2A/B) and pathogenic or likely pathogenic variants in APC, SMAD4, and PIK3CA. The APC and SMAD4 variants occurred at allele frequencies suggestive of germline mutations, raising the possibility that this patient may have an inherited cancer predisposition syndrome. Conclusions. We present two cases which extend the upper age limit for reported pancreatoblastoma, including one with genetic findings suggestive of an inherited cancer predisposition syndrome.

The diverse morphology and immunophenotype of ovarian endometrioid carcinomas

Endometrioid carcinoma (EC) accounts for approximately 10-12% of ovarian epithelial malignancies but compared to its relative frequency, results in a disproportionate number of diagnostically difficult cases with potential for misdiagnosis. In this review the protean and diverse morphologies of ovarian EC are discussed, including 'metaplastic' changes, EC with spindle cell differentiation/corded and hyalinised features and EC with sex cord-like formations. The propensity for 'transdifferentiation' in ovarian ECs is also discussed, one example being the association with a somatically derived yolk sac tumour. Although immunohistochemistry may be extremely useful in diagnosing EC and in distinguishing between EC and other ovarian epithelial malignancies, metastatic neoplasms and sex cord-stromal tumours, this review also discusses the propensity for ovarian EC to exhibit an aberrant immunophenotype which may compound diagnostic uncertainty. The genomic characteristics of these tumours and the recent 'incorporation' of seromucinous carcinoma into the EC category are also discussed.

Clinicopathologic Evaluation of CTNNB1 Mutations in High-Intermediate Risk Endometrial Endometrioid Carcinoma

CTNNB1 mutations convey increased risk of recurrence in low-risk endometrial endometrioid carcinoma (EEC). Results from previous high-intermediate risk (HIR) cohorts are mixed. The aims of this study were to correlate CTNNB1 mutational status with clinical outcomes and to evaluate the relationship between CTNNB1 mutations and the 4 prognostic subgroups defined by The Cancer Genome Atlas in HIR EEC. CTNNB1 mutational status was determined by Sanger sequencing of exon 3 of the CTNNB1 gene. Mismatch repair, POLE , p53, and L1 cell-adhesion molecule (L1CAM) status were also evaluated. Descriptive statistics and survival analyses were performed. Eighty-eight cases of HIR EEC were identified, of which 22 (25%) were CTNNB1 mutant ( CTNNB1 -mut) and 66 (75%) were wild-type ( CTNNB1 -WT). Median follow-up was 60 mo. Recurrence occurred in 13/88 (15%) patients. Recurrence rates were not significantly different between patients with CTNNB1- mut and CTNNB1- WT tumors (14% vs. 15%, P =0.86). Recurrence-free survival and overall survival were not significantly different (recurrence-free survival hazard ratio: 0.97, 95% confidence interval: 0.27-3.52, P =0.96; overall survival hazard ratio: 0.23, 95% confidence interval: 0.03-1.71, P =0.15). Mismatch repair deficiency was more prevalent in CTNNB1 -WT compared with CTNNB1 -mut tumors (46% vs. 14%, P =0.01); prevalence of POLE mutations and aberrant p53 were not significantly different. In contrast to patients with low-risk EEC, no differences in recurrence or survival were found in patients with HIR EEC with CTNNB1- mut compared with CTNNB1 -WT tumors.

PTEN overexpression and nuclear β-catenin stabilization promote morular differentiation through induction of epithelial-mesenchymal transition and cancer stem cell-like properties in endometrial carcinoma

BACKGROUND

Although a lack of functional PTEN contributes to tumorigenesis in a wide spectrum of human malignancies, little is known about the functional role of its overexpression in the tumors. The current study focused on PTEN overexpression in endometrial carcinoma (Em Ca).

METHODS

The functional impact of PTEN overexpression was assessed by Em Ca cell lines. Immunohistochemical analyses were also conducted using 38 Em Ca with morular lesions.

RESULTS

Em Ca cell lines stably overexpressing PTEN (H6-PTEN) exhibited epithelial-mesenchymal transition (EMT)-like features, probably through β-catenin/Slug-meditated suppression of E-cadherin. PTEN overexpression also inhibited cell proliferation, accelerated cellular senescence, increased apoptotic features, and enhanced migration capability. Moreover, H6-PTEN cells exhibited cancer stem cell (CSC)-like properties, along with high expression of aldehyde dehydrogenase 1 and CD44s, a large ALDH 1^high population, enriched spheroid formation, and β-catenin-mediated upregulation of cyclin D2, which is required for persistent CSC growth. In clinical samples, immunoreactivities for PTEN, as well as CSC-related molecules, were significantly higher in morular lesions as compared to the surrounding carcinomas. PTEN score was positively correlated with expression of nuclear β-catenin, cytoplasmic CD133, and CD44v6, and negatively with cell proliferation. Finally, estrogen receptor-α (ERα)-dependent expression of Ezrin-radixin-moesin-binding phophoprotein-50 (EBP50), a multifunctional scaffolding protein, acts as a negative regulator of morular formation by Em Ca cells through interacting with PTEN and β-catenin.

CONCLUSION

In the abscess of ERα/EBP50 expression, PTEN overexpression and nuclear β-catenin stabilization promote the establishment and maintenance of morular phenotype associated with EMT/CSC-like features in Em Ca cells. Video Abstract.

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.

Morules but Not Squamous Differentiation are a Reliable Indicator of CTNNB1 (β-catenin) Mutations in Endometrial Carcinoma and Precancers

Although collectively regarded as "squamous differentiation (SD)" in endometrial endometrioid carcinoma (EEC) and atypical hyperplasia/endometrioid intraepithelial neoplasia (AH/EIN), morules (often referred to as "squamous morules") and true SD may represent two distinct phenomena. Here, we explored the distinction between morules versus SD and investigated the association of morules and SD with CTNNB1 mutations. A total of 270 cases of EEC and AH/EIN were studied, including EEC with (n=36) or without (n=36) morules and AH/EIN with (n=80) or without (n=118) morules. Cases were analyzed by immunohistochemistry and selected cases (n=20) by targeted next-generation sequencing panel. Near-perfect agreement was found between morules and glandular β-catenin nuclear staining in AH/EIN and EEC. A strong positive association was found between morules and glandular β-catenin nuclear staining (P<0.0001, Φ=0.59 in AH/EIN; P<0.0001, Φ=0.85 in EEC). There was no association between (1) morules and glandular PAX2 or PTEN aberrant expression or (2) SD and aberrant expression of β-catenin, PAX2 or PTEN (Φ=0.09, β-catenin; Φ=0.16, PAX2; Φ=0.13, PTEN). CTNNB1 mutations were identified in all 20 selected morule-containing cases (100%). Next-generation sequencing was performed on 2 (preprogestin and postprogestin treatment) biopsies from 1 patient, revealing identical mutational profile in morules and glands. In conclusion, (1) SD and morules are distinct biological phenomena; (2) the presence of morules, but not SD, is a reliable indicator of CTNNB1 mutations in EEC and AH/EIN. Our findings demonstrate that SD and morules are distinct biological phenomena. Since morules but not SD are associated with β-catenin mutations, the distinction is clinically relevant and should be included in diagnostic reports.

Clinical implications of morular metaplasia in fertility-preserving treatment for atypical endometrial hyperplasia and early endometrial carcinoma patients

Objective

Morular metaplasia (MM) is a benign epithelial metaplasia that sometimes appears in atypical endometrial hyperplasia (AEH) and endometrioid endometrial carcinoma (EEC). However, the clinical implications of MM for fertility-preserving treatment in AEH and EEC patients are unclear. This study investigated the clinical features and impact of MM on the efficacy of fertility-preserving treatment.

Methods

We retrospectively studied 427 AEH and EEC patients who received fertility-preserving treatment. Clinical features, treatment efficacy, and onco-fertility results were compared between patients with and without MM.

Results

MM appeared in 147 of 427 (34.4%) patients. Among them, 49 (33.3%) had MM only before treatment (BEF group), 32 (21.8%) had sustained MM before and during treatment (SUS group), and 66 (44.9%) had MM only during treatment (DUR group). The BEF group had a higher 12-month CR rate (98.0% vs 85.7%, p = 0.017) and shorter therapeutic duration to achieve CR (4.0 vs 5.7 months, p = 0.013) than the non-MM group had. In comparison with the non-MM group, the SUS and DUR groups had a lower CR rate after 7 months of treatment (SUS vs non-MM, 37.5% vs 61.1%, p = 0.010; DUR vs non-MM 33.3% vs. 61.1%, p < 0.001), and a longer median therapeutic duration to achieve CR (SUS vs non-MM, 7.6 vs. 4.0 months, p = 0.037; DUR vs non-MM, 7.9 vs. 4.0 months, p < 0.001).

Conclusion

Appearance of MM only before treatment was positively correlated with outcome of fertility-preserving treatment, while sustained MM or appearance of MM only during treatment implied poorer outcome of fertility-preserving treatment in AEH and EEC patients.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00404-021-06382-3.

WT1 Positive Ovarian Endometrioid Tumors: Observations From Consult Cases and Strategies for Distinguishing From Serous Neoplasms

Ovarian endometrioid carcinoma, more than any other type of ovarian epithelial malignancy, demonstrates a varied morphology which can cause problems in diagnosis. In tubo-ovarian tumor pathology, WT1 is a commonly used marker as it is consistently expressed in low-grade and high-grade serous carcinomas and is often considered a specific marker of a serous phenotype. However, ovarian endometrioid neoplasms may also express WT1 which may contribute to misdiagnosis. We report our experience with 23 ovarian endometrioid neoplasms (4 borderline tumors, 19 carcinomas), mainly received in consultation, which were WT1 positive (diffuse in 11 cases) which often contributed to misdiagnosis. Endometriosis was identified in the same ovary in 6 cases and squamous elements in 7. We describe strategies for distinguishing such neoplasms, which may exhibit morphologic overlap with serous tumors, from low-grade and high-grade serous carcinomas and stress that a diagnosis of HGSC is unlikely with two grossly and histologically normal fallopian tubes. We also stress that a panel of markers should always be used rather than relying on a single marker and that when the morphology is classical of an endometrioid carcinoma, diagnostic immunohistochemistry is not needed given the potential for confusion in cases showing "aberrant" staining. We also discuss the phenomenon of "aberrant" immunohistochemical staining in endometrioid carcinomas which appears more common than in other ovarian carcinomas.

Gynaecological or gastrointestinal origin? Recognising Müllerian neoplasms with gastrointestinal phenotype and determining the primary site in selected entities

Recognising metastatic gastrointestinal and pancreatobiliary tumours to gynaecological sites may be challenging, as primary Müllerian tumours can demonstrate similar histological features. Endocervical adenocarcinomas can be of gastric and intestinal types, endometrial lesions may show gastrointestinal phenotype, and finally, mucinous tumours with secondary involvement of the ovaries may mimic primary neoplasms. The aim of this review is to address selected neoplastic entities of the gynaecological tract with gastric and intestinal differentiation and provide helpful clinical and pathological parameters for the diagnosis. A brief overview of metastatic tumours originating from the gastrointestinal and pancreaticobiliary tracts is also provided, including the most common pathological features.

Corded and Hyalinized Endometrioid Adenocarcinoma (CHEC) of the Uterine Corpus are Characterized by CTNNB1 Mutations and Can Show Adverse Clinical Outcomes

Corded and hyalinized endometrioid adenocarcinoma (CHEC) is a morphologic variant of endometrioid adenocarcinoma that is typically low-grade [International Federation of Gynecology and Obstetrics (FIGO) grade 1-2]. CHEC exhibits a biphasic appearance with gland forming adenocarcinoma merging with a diffuse component with corded growth often in a hyalinized matrix; squamous differentiation is frequent and osteoid production can be seen. This morphologic appearance can invoke a large differential diagnosis including carcinosarcoma. CHEC is thought to be associated with good clinical outcome although the available data is sparse. We performed detailed clinical, morphologic, immunohistochemical, and molecular analyses on a cohort of 7 CHEC. Six cases exhibited features of classic low-grade CHEC while one case showed greater cytologic atypia (high-grade CHEC). Patient age ranged from 19 to 69 yr. Four patients presented at stage I, 2 at stage II, and 1 at stage III. All tumors demonstrated nuclear staining for beta-catenin and loss of E-cadherin in the corded and hyalinized component. There was relative loss of epithelial markers. Loss of PTEN and ARID1A was seen in 4 and 3 tumors, respectively, and 1 tumor displayed loss of MLH1 and PMS2. Next-generation sequencing revealed CTNNB1 and PI3K pathway mutations in all 7 cases with TP53 and RB1 alterations in the high-grade CHEC. Clinical follow-up was available for 6 patients; 2 died of disease (48 and 50 mo), 2 are alive with disease (both recurred at 13 mo), and 2 have no evidence of disease (13 and 77 mo). Our study shows that CHEC universally harbors CTNNB1 mutations with nuclear staining for beta-catenin, can rarely show high-grade cytology, and can be associated with adverse clinical outcomes.

Immunophenotype of Atypical Polypoid Adenomyoma of the Uterus: Diagnostic Value and Insight on Pathogenesis

Atypical polypoid adenomyoma (APA) is a rare uterine lesion constituted by atypical endometrioid glands, squamous morules, and myofibromatous stroma. We aimed to assess the immunophenotype of the 3 components of APA, with regard to its pathogenesis and its differential diagnosis. A systematic review was performed by searching electronic databases from their inception to January 2019 for immunohistochemical studies of APA. Thirteen studies with 145 APA cases were included. APA glands appeared analogous to atypical endometrial hyperplasia (endometrioid cytokeratins pattern, Ki67≤50%, common PTEN loss, and occasional mismatch repair deficiency); the prominent expression of hormone receptors and nuclear β-catenin suggest that APA may be a precursor of "copy number-low," CTNNB1-mutant endometrial cancers. Morules appeared as a peculiar type of hyperdifferentiation (low KI67, nuclear β-catenin+, CD10+, CDX2+, SATB2+, p63-, and p40-), analogous to morular metaplasia in other lesions and distinguishable immunohistochemically from both conventional squamous metaplasia and solid cancer growth. Stroma immunphenotype (low Ki67, α-smooth-muscle-actin+, h-caldesmon-, CD10-, or weak and patchy) suggested a derivation from a metaplasia of normal endometrial stroma. It was similar to that of nonatypical adenomyoma, and different from adenosarcoma (Ki67 increase and CD10+ in periglandular stroma) and myoinvasive endometrioid carcinoma (h-caldesmon+ in myometrium and periglandular fringe-like CD10 pattern).

Therapeutic potential of the human endogenous retroviral envelope protein HEMO: a pan-cancer analysis

Human endogenous retroviruses represent approximately 8% of our genome. Most of these sequences are defective except for a few genes such as the ancestral retroviral HEMO envelope gene (Human Endogenous MER34 ORF), recently characterized by our group. In this study, we characterized transcriptional activation of HEMO in primary tumors from The Cancer Genome Atlas (TCGA) and in metastatic tumors from a Gustave Roussy cohort. Pan‐cancer detection of the HEMO protein in a series of patient samples validated these results. Differential gene expression analysis in various TCGA datasets revealed a link between HEMO expression and activation of Wnt/β‐catenin signaling, in particular in endometrial cancer. Studies on cell models led us to propose that the Wnt/β‐catenin pathway could act as an upstream regulator of this retroviral endogenous sequence in tumor condition. Characterization of transcriptomic profiles of both HEMO^Low and HEMO^High tumors suggested that activation of HEMO is negatively associated with immune response signatures. Taken together, these results highlight that HEMO, as an endogenous retroviral envelope protein specifically expressed in tumors, represents a promising tumor biomarker and therapeutic target.

Nuclear Beta-Catenin Expression in Endometrioid Intraepithelial Neoplasia (Atypical Hyperplasia) Does Not Predict Carcinoma on Subsequent Hysterectomy

Beta-catenin (BC) mutations are associated with a high risk of recurrence in otherwise low-grade, early-stage uterine endometrioid adenocarcinomas. Recent literature suggests nuclear BC expression by immunohistochemistry is highly sensitive and specific for BC mutations. The significance of BC expression in endometrioid intraepithelial neoplasia (EIN/atypical hyperplasia) and its relationship to altered differentiation patterns in EIN has yet to be fully explored. Cases meeting current diagnostic criteria for EIN based on H&E examination were obtained from 2 institutions (years 1999-2014). Patterns of altered differentiation (eg, tubal, squamous morular metaplasia, mucinous, secretory) were noted. Representative blocks were stained for BC, and expression patterns recorded. Follow-up and demographic data was obtained from the electronic medical record. Ninety-six cases were included (84 biopsies, 12 hysterectomies). BC nuclear expression was identified in 41 cases (42.7%), with 33 of 41 demonstrating foci of nonmorular BC staining. BC staining in any component of EIN was not significantly associated with the presence of carcinoma on subsequent hysterectomy (P=0.79). When restricting to nonmorular BC, the results were the same (P=0.56). Cases with tubal differentiation were significantly less likely to demonstrate nonmorular BC than cases with no specific pattern of differentiation (P<0.01). EIN frequently demonstrates BC nuclear positivity, especially in cases without tubal differentiation. BC nuclear expression in EIN does not appear to be associated with an increased likelihood of carcinoma on subsequent hysterectomy. Our results do not support routine use of BC immunohistochemistry as a prognostic biomarker in cases of EIN.

Diagnostic Pitfalls Related to Morular Metaplasia in Endometrioid Carcinoma: An Underestimated Issue

Here, we present a case that highlights the crucial pitfalls related to the presence of morular metaplasia (MM) in endometrioid carcinoma, which are insufficiently recognized in the routine pathology practice. A 45-year-old woman underwent hysterectomy with rectosigmoidectomy due to a 11-cm mass involving uterus, right ovary, and rectosigmoid colon. Histologically, the lesion appeared as a predominantly solid carcinoma with a minor glandular component. Results of the first immunohistochemical analysis suggested a colorectal origin (PAX8-, CK7-, WT1-, hormone receptors-, and CDX2+ in the absence of mucinous features). Subsequent immunohistochemistry (nuclear β-catenin+, CD10+, and low ki67 in the solid areas) supported a diagnosis of endometrioid carcinoma with diffuse MM. This case remarks that morphological and immunohistochemical features of MM may conceal the glandular architecture and the typical immunophenotype of endometrioid carcinomas. Acknowledging the diagnostic issues related to MM appears crucial to avoid misdiagnosis and inappropriate patient management.

Does endometrial morular metaplasia represent odontogenic differentiation?

The nature of endometrial morular metaplasia (MorM) is still unknown. The nuclear β-catenin accumulation and the not rare ghost cell keratinization suggest a similarity with hard keratin-producing odontogenic and hair matrix tumors rather than with squamous differentiation. We aimed to compare MorM to hard keratin-producing tumors. Forty-one hard keratin-producing tumors, including 26 hair matrix tumors (20 pilomatrixomas and 6 pilomatrix carcinomas) and 15 odontogenic tumors (adamantinomatous craniopharyngiomas), were compared to 15 endometrioid carcinomas with MorM with or without squamous/keratinizing features. Immunohistochemistry for β-catenin, CD10, CDX2, ki67, p63, CK5/6, CK7, CK8/18, CK19, and pan-hard keratin was performed; 10 cases of endometrioid carcinomas with conventional squamous differentiation were used as controls. In adamantinomatous craniopharyngiomas, the β-catenin-accumulating cell clusters (whorl-like structures) were morphologically similar to MorM (round syncytial aggregates of bland cells with round-to-spindled nuclei and profuse cytoplasm), with overlapping squamous/keratinizing features (clear cells with prominent membrane, rounded squamous formations, ghost cells). Both MorM and whorl-like structures consistently showed positivity for CD10 and CDX2, with low ki67; cytokeratins pattern was also overlapping, although more variable. Hard keratin was focally/multifocally positive in 8 MorM cases and focally in one conventional squamous differentiation case. Hair matrix tumors showed no morphological or immunophenotypical overlap with MorM. MorM shows wide morphological and immunophenotypical overlap with the whorl-like structures of adamantinomatous craniopharyngiomas, which are analogous to enamel knots of tooth development. This suggests that MorM might be an aberrant mimic of odontogenic differentiation.

Relationship between morular metaplasia and squamous differentiation in endometrial carcinoma

Morular metaplasia (MM) is a peculiar type of metaplastic change commonly observed in endometrial lesions, which is defined by the absence of overt squamous features and a characteristic immunophenotype. The nature of MM and its relationship with conventional squamous differentiation (SD) is still undefined. Here, we present a morphological and immunophenotypical study of cases with mixed MM/SD and conventional SD, providing new insights on this field. Twenty cases of endometrioid carcinoma (10 with mixed MM and SD and 10 with conventional SD) were assessed by immunohistochemistry for β-catenin, CD10, CDX2, ki67, p63, p40, estrogen receptor (ER), progesterone receptor (PR) and cytokeratins (CK) 5/6, 7, 8/18 and 19. In mixed MM/SD cases, SD was mostly located within the MM areas; several degrees of SD development were observed within MM, from cells with larger cytoplasm and prominent membrane, to overt SD with morular shape and ghost cell keratinization. In the MM→SD transition, there was progressive loss of nuclear β-catenin, CD10, CDX2 and CK8/18 expression, increase of CK5/6 and CK7 expression, and stable CK19 positivity. ER, PR and ki67/MIB1 expression was low-to-negative in both MM and SD. The squamous cell markers p63 and p40 were mostly expressed at the interfaces between MM and SD. Conventional SD cases showed direct transition from glandular epithelium to SD with a surface growth and no ghost cell keratinization; immunohistochemistry showed strong positivity for ER, PR and all CKs, basal positivity for p63, p40 and ki67/MIB1, negativity for nuclear β-catenin, CD10 and CDX2. In conclusion, MM appears as the precursor of a peculiar form of SD, which differs morphologically and immunophenotypically from conventional SD. Defining MM based on the absence of overt squamous might not be meaningful. Further studies are necessary to clarify the nature of MM.

Endometrial Gastric (Gastrointestinal)-type Mucinous Lesions: Report of a Series Illustrating the Spectrum of Benign and Malignant Lesions

With the recent elucidation of gastric-type lesions in the female genital tract (especially in the cervix), occasional cases of endometrial adenocarcinoma displaying gastric (gastrointestinal) differentiation have been reported, but they are currently not recognized as a distinct pathologic entity. We report 9 cases of endometrial mucinous lesions which exhibit gastric (gastrointestinal)-type features by morphology and immunohistochemistry, including 4 adenocarcinomas and 5 benign mucinous lesions, in patients aged 32 to 85. The adenocarcinomas showed gastric-type morphology in all 4 cases and goblet cells in 1, with a component of benign gastric-type mucinous glands in 1 case. Immunohistochemically, the adenocarcinomas were positive for CK7 (4/4), CEA (4/4), MUC6 (3/3), PAX8 (3/4), CK20 (2/4), CDX2 (2/4), and estrogen receptor (1/4). They were negative for Napsin A (0/3), with mutation-type p53 staining in 2/4 cases, block-type p16 positivity in 1/4, and scattered chromogranin-positive cells in 1/2. Targeted next-generation sequencing revealed nonsense mutation in RB1 gene for the case with block-positive p16. Follow-up was available in all adenocarcinoma cases and indicated aggressive behavior; 2 patients were dead of disease at follow-up of 7 months to 3 years, 1 was alive with progression at 9 months, and 1 was alive without disease at 7 months. The benign mucinous lesions (including the benign component in 1 adenocarcinoma) exhibited gastric-type morphologic features in 5/6 cases, goblet cells in 5/6, and Paneth-like neuroendocrine cells in 1/6. These benign mucinous lesions were associated with an endometrial polyp in 5/6 cases. Cytologic atypia was present in 2/6 cases and a lobular architecture resembling cervical lobular endocervical glandular hyperplasia in 4/6. Immunohistochemically, the benign mucinous lesions were positive for CK7 (5/5), CDX2 (5/6), estrogen receptor (4/5), MUC6 (4/5), CK20 (3/5), PAX8 (3/5), and CEA (2/4), with scattered chromogranin-positive cells in 4/4 cases; in all cases tested Napsin A was negative, p53 was wild-type and p16 was negative. We propose the term "endometrial gastric (gastrointestinal)-type adenocarcinoma" for this distinctive group of rare aggressive endometrial carcinomas. We believe that benign or atypical gastric (gastrointestinal)-type mucinous lesions are putative precursors for these adenocarcinomas, comparable to recognized premalignant gastric-type lesions in the cervix and the vagina. Future recognition and reporting of these gastric-type endometrial mucinous lesions will help delineate their pathogenesis and clinical significance.

Extensive squamous metaplasia (morulosis) of the endometrium as a clinical and pathological problem: a case report and literature study

The article presents a case of a 28-year-old woman with so-called morulosis - a form of squamous metaplasia of the endometrium, which may mimic malignancy. The term 'morulosis' indicates extensive squamous mulberry-like metaplasia, which in a large part or nearly entirely affects endometrium, whereas in turn, benign squamous metaplasia or single morules, refers to a limited, usually small regional pathology of endometrium. Because the endometrial glands and stroma gradually undergo the process of squamous metaplasia, in a scanty biopsy material the picture may lead to overdiagnosis. In the epithelioid regions small inactive glands with an immunofenotype different from the remaining endometrium might be observed. So far 21 cases have been reported in English literature. The patients (age 19-45) had presented with abnormal bleeding, infertility or after hormonal therapy. The mechanism of the extensive squamous metaplasia of endometrium is still not clear. The prevailing view holds that morulosis appears to be a result of hormonal imbalance. To shed light on possible pathogenic background of morulosis, we present a case of particularly severe extensive squamous metaplasia of the endometrium (morulosis).

A COEUR cohort study of SATB2 expression and its prognostic value in ovarian endometrioid carcinoma

The aim of this study was to describe the expression of special AT-rich sequence-binding protein 2 (SATB2) in ovarian endometrioid carcinoma (EC). SATB2 is a nuclear matrix-associated transcription factor that is associated with abnormal expression in certain cancers but has not been reported for ovarian carcinoma. SATB2 mRNA and protein expression was first assessed in a pilot cohort of 26 samples by Affymetrix microarray and by routine immunohistochemistry on a small tissue microarray. A large multicenter validation cohort representing the well-characterized cases of 235 ovarian EC from the Canadian Ovarian Experimental Unified Resource (COEUR) was then used to validate this result and to assess the prognostic impact of SATB2 expression. SATB2 staining was scored as negative, weak, moderate, and strong intensity, and by percentage of stained cells. No SATB2 expression was observed in clear cell carcinomas but 10% (n = 3) of the ECs in the pilot cohort showed SATB2 expression. In the validation cohort, strong expression was observed in 11% of ECs, while weak or moderate expression levels were detected in 12% of cases. Evaluation of SATB2 expression with clinicopathological parameters revealed an association with patient age and Federation International of Gynecology and Obstetrics grade but not with disease stage or postoperative residual disease. Any expression of SATB2, independent of intensity, was also associated with longer survival and improved progression-free survival with hazard ratio (HR) = 0.14 (95% CI 0.03-0.56) and HR = 0.16 (95% CI 0.02-1.24) respectively. A greater beneficial effect was observed in patients with stage III/IV disease compared to patients with stage I/II disease. Furthermore, direct comparison of SATB2 with other reported prognostic biomarkers such as progesterone receptor, CDX2 and β-catenin within this cohort showed that SATB2 had the strongest association with survival. Given the current lack of accurate prognostic factors for these patients, SATB2 has promising clinical utility and warrants further study.

Endometrial Endometrioid Carcinoma With Ovarian Metastasis Showing Morula-like Features in a Patient With Cowden Syndrome: A Case Report

Cowden syndrome (CS) is a multiple hamartoma syndrome associated with the development of various tumors, including endometrial cancer. However, the histology of CS-associated endometrial cancer remains to be fully described. To our knowledge, this is the first report of a patient with CS having endometrial endometrioid carcinoma with ovarian metastasis demonstrating morula-like features. A 31-yr-old, nulliparous, Japanese woman presented with abnormal genital bleeding. Endometrial biopsy revealed endometrioid carcinoma with an extensive morular formation, partially resembling atypical polypoid adenomyoma (APAM). Moreover, she had a past history of bilateral breast cancer and a family history of juvenile breast cancer in her mother. Genetic testing revealed they shared the same pathogenic germline PTEN mutation. She underwent an abdominal hysterectomy, bilateral salpingo-oophorectomy, and pelvic lymph node biopsy. Pathologic examination revealed endometrial endometrioid carcinoma with APAM-like histology. Furthermore, the solid components with morula-like morphology and immunophenotypes showed myometrial invasion and ovarian metastasis (FIGO stage IIIA/pT3aN0M0). The present case highlights the need for careful assessment of myometrial invasion and extrauterine spread for appropriate gynecologic treatment even if endometrial biopsy shows APAM-like histology. Moreover, characterization of CS-associated endometrial cancers is required.

A case of nasal low-grade non-intestinal-type adenocarcinoma with aberrant CDX2 expression and a novel SYN2-PPARG gene fusion in a 13-year-old girl

We report the first patient (a 13-year-old girl) with a sinonasal low-grade non-intestinal-type adenocarcinoma showing aberrant CDX2 expression both within morular areas and in the tubular component and demonstrate for the first time a SYN2-PPARG gene fusion in this tumor type. The tumor arose from the nasal septum and had not spread beyond the nasal cavity.

Two Cases of Sinonasal Non-Intestinal-Type Adenocarcinoma with Squamoid Morules Expressing Nuclear β-Catenin and CDX2: A Curious Morphologic Finding Supported by Molecular Analysis

Sinonasal non-intestinal-type adenocarcinoma (non-ITAC) is a rare, morphologically diverse neoplasm of the head and neck. Squamoid morular metaplasia has recently been reported as an occasional finding in non-ITAC. Interestingly, these squamoid morules often show aberrant expression of CDX2 as well as nuclear expression of β-catenin, similar to other tumors that show this type of metaplasia, but the underlying mechanism responsible for this finding is not completely understood. We present two cases of low-grade non-ITAC with squamoid morules coexpressing CDX2 and nuclear β-catenin by immunohistochemistry, both of which were found to harbor a mutation in CTNNB1, the gene encoding β-catenin. This finding provides support that an alteration in the β-catenin pathway, including mutations in the β-catenin gene itself, is responsible for this recently described morphologic phenomenon in non-ITAC.

Shadow Cell Differentiation: A Comparative Analysis of Modes of Cell Death with Apoptosis and Epidermal/Trichilemmal Keratinization

Shadow cells are characterized by an eosinophilic cytoplasm and a ghost-like nuclear contour; the cell shape is preserved, in spite of nuclear disappearance. Shadow cell nests (SCNs) are frequently observed in pilomatricoma (PMX), where the transitional cells immediately adjacent to SCNs often have a crescent-shaped nucleus showing fragmentation similar to that of apoptotic bodies. They show nuclear accumulation of beta-catenin and DNA double strand breaks (as revealed by in situ 3′-tailing reaction or immunohistochemistry for single-stranded DNA [ssDNA]), while they are negative for cleaved caspase-3 or cleaved lamin A, suggesting that shadow cell differentiation (SCD) is a caspase-independent programmed cell death. SCD can be differentiated from epidermal keratinization (EK) and trichilemmal keratinization (TK) based on the expression pattern of beta-catenin, ssDNA, and caspase-14/CD138. SCD is observed not only in PMX, but also sometimes in basal cell carcinomas, gonadal teratomas, and various extra-cutaneous carcinomas. In particular, SCNs are found in 24$ of endometrial adenoacanthoma and are derived from squamoid morules. This establishes a link between basaloid cells in PMX and squamoid morules in endometrial adenoacanthomas as common precursors of shadow cells. Overall, it is suggested that SCD is different from, but partly similar to, apoptosis and that SCD and EK/TK should be differentiated from the standpoint of cell death/differentiation.

Histopathologic Features of Colorectal Adenoma and Adenocarcinoma Developing Within Inflammatory Polyps in Miniature Dachshunds

Biopsy samples of colorectal polyps were collected and examined from 67 Miniature Dachshund dogs (including 35 cases with an additional biopsy). Histopathologic diagnoses of the initial biopsy samples were "inflammatory polyp" in 52 cases (78%), "adenoma" in 10 cases (15%), and "adenocarcinoma" in 5 cases (8%). Eight of 10 cases (80%) diagnosed as adenoma also had inflammatory polyp lesions in the same specimen. A second biopsy was performed in 25 cases (48%) initially diagnosed with inflammatory polyp. Pathologic diagnoses for the second biopsy were inflammatory polyp in 11 cases (44%), adenoma in 9 cases (36%), and adenocarcinoma in 5 cases (20%). The number of beta-catenin-positive nuclei in epithelial cells was significantly higher in adenoma (46%) and adenocarcinoma (75%) as compared with inflammatory polyp (6%). Normal epithelial cells and hyperplastic goblet cells in inflammatory polyps showed homogeneous positive cytoplasmic immunoreactivity for adenomatous polyposis coli (APC) antigen. However, APC expression was decreased in areas of intense nuclear beta-catenin expression in adenoma and adenocarcinoma lesions. Foci of cytokeratin 5/6-positive squamous cell-like neoplastic cells showed intense beta-catenin nuclear expression that was similar to squamous morules described in human colorectal tumors. The results of the present study suggest that the inflammatory polyp in Miniature Dachshunds is a progressive disease that may develop into adenoma and/or adenocarcinoma. In addition, immunohistochemical findings suggest that aberrations of APC and beta-catenin expression may be involved in tumor development within the inflammatory polyp lesions.

Diagnostic immunohistochemistry in gynaecological neoplasia: a brief survey of the most common scenarios

Immunohistochemistry is a valuable adjunct in routine gynaecological pathology. The molecular revolution has redesigned knowledge of gynaecological cancers and refined histological classification. The direct consequence has been the progressive introduction of new immunostainings for diagnostic and classification purposes. Hence, we review the routine diagnostic use of immunohistochemistry in the field of gynaecological neoplasia. We reviewed the immunomarkers useful in gynaecological pathology according to literature revision, our personal experience and research findings. We discuss the application of immunohistochemistry to reach the most accurate diagnosis in morphologically equivocal cases of gynaecological pathology and present the appropriate panel of immunomarkers in the most common scenarios of gynaecological pathology. This short review provides an updated overview of the essential immunohistochemical markers currently used in the diagnostics of gynaecological malignancies along with their molecular rationale.

Blinded histopathological characterisation of POLE exonuclease domain-mutant endometrial cancers: sheep in wolf's clothing

AIMS

POLE exonuclease domain mutations identify a subset of endometrial cancer (EC) patients with an excellent prognosis. The use of this biomarker has been suggested to refine adjuvant treatment decisions, but the necessary sequencing is not widely performed and is relatively expensive. Therefore, we aimed to identify histopathological and immunohistochemical characteristics to aid in the detection of POLE-mutant ECs.

METHODS AND RESULTS

Fifty-one POLE-mutant endometrioid, 67 POLE-wild-type endometrioid and 15 POLE-wild-type serous ECs were included (total N = 133). An expert gynaecopathologist, blinded to molecular features, evaluated each case (two or more slides) for 16 morphological characteristics. Immunohistochemistry was performed for p53, p16, MLH1, MSH2, MSH6, and PMS2. POLE-mutant ECs were characterised by a prominent immune infiltrate: 80% showed peritumoral lymphocytes and 59% showed tumour-infiltrating lymphocytes, as compared with 43% and 28% of POLE-wild-type endometrioid ECs, and 27% and 13% of their serous counterparts (P < 0.01, all comparisons). Of POLE-mutant ECs, 33% contained tumour giant cells; this proportion was significantly higher than that in POLE-wild-type endometrioid ECs (10%; P = 0.003), but not significantly different from that in serous ECs (53%). Serous-like features were as often (focally) present in POLE-mutant as in POLE-wild-type endometrioid ECs (6-24%, depending on the feature). The majority of POLE-mutant ECs showed wild-type p53 (86%), negative/focal p16 (82%) and normal mismatch repair protein expression (90%).

CONCLUSIONS

A simple combination of morphological and immunohistochemical characteristics (tumour type, grade, peritumoral lymphocytes, MLH1, and p53 expression) can assist in prescreening for POLE exonuclease domain mutations in EC, increasing the probability of a mutation being detected from 7% to 33%. This facilitates the use of this important prognostic biomarker in routine pathology.

Practical Immunohistochemistry in Neoplastic Pathology of the Gastrointestinal Tract, Liver, Biliary Tract, and Pancreas

CONTEXT

- Immunomarkers with diagnostic, therapeutic, or prognostic values have been increasingly used to maximize the benefits of clinical management of patients with neoplastic diseases of the gastrointestinal tract, liver, biliary tract, and pancreas.

OBJECTIVES

- To review the characteristics of immunomarkers that are commonly used in surgical pathology practice for neoplasms of the gastrointestinal tract, liver, biliary tract, and pancreas, and to summarize the clinical usefulness of immunomarkers that have been discovered in recent years in these fields.

DATA SOURCES

- Data sources include literature review, authors' research data, and personal practice experience.

CONCLUSIONS

- Immunohistochemistry is an indispensable tool for the accurate diagnosis of neoplastic diseases of the gastrointestinal tract, liver, biliary tract, and pancreas. Useful immunomarkers are available to help distinguish malignant neoplasms from benign conditions, determine organ origins, and subclassify neoplasms that are morphologically and biologically heterogeneous. Specific immunomarkers are also available to help guide patient treatment and assess disease aggressiveness, which are keys to the success of personalized medicine. Pathologists will continue to play a critical role in the discovery, validation, and application of new biomarkers, which will ultimately improve patient care.

Primary Endometrial Yolk Sac Tumor With Endodermal-Intestinal Differentiation Masquerading as Metastatic Colorectal Adenocarcinoma

Yolk sac tumors (YSTs) with a somatic glandular pattern can be difficult to recognize histologically because they reproduce developing intestinal, hepatic, or lung tissue and can express markers such as CDX2 and TTF1. We report an unusual case of a primary endometrial YST showing florid endodermal-intestinal differentiation in a 63-yr-old woman with a history of colorectal adenocarcinoma. Histologically, the tumor exhibited a glandular and papillary architecture and showed widespread immunoreactivity for CDX2 and focal staining for CK20 and CEA, mimicking metastatic colorectal carcinoma on biopsy. The presence of subnuclear cytoplasmic clearing and positive staining for germ cell markers, however, pointed toward a diagnosis of primary endometrial YST, and this was supported by the radiologic and the subsequent pathologic finding of a primary endometrial-based lesion. YSTs in this age group usually arise in association with somatic tumors and in this case a small focus of coexistent endometrioid adenocarcinoma was identified within the uterus. Despite surgery and adjuvant chemotherapy, the patient showed disease progression with liver and lung metastases 6 mo postoperatively.

Intestinal differentiated mucinous adenocarcinoma of the endometrium with sporadic MSI high status: a case report

Background

Intestinal differentiation of primary mucinous adenocarcinoma of the uterine corpus is exceedingly rare in comparison to the approximately 25% rate in endocervical and ovarian mucinous carcinoma. Additionally, little is known about the related genetic and epigenetic alterations, even though large-scale molecular characterisation of the different types of endometrial cancer took place in the TCGA project along the entities defined by the recent WHO classification.

Case presentation

We present a 62-year-old patient harbouring a primary mucinous carcinoma of the uterine corpus with a morphological resemblance to mucinous colorectal adenocarcinoma. The intestinal differentiation was substantiated by CDX2 and CK20 positivity in the absence of PAX8, p16, WT1, p53, ER, PgR, AFP, SALL4 and Glypican3. A high MSI status with MLH1 hypermethylation was revealed by molecular testing.

Conclusion

Intestinal differentiation of mucinous adenocarcinoma of the endometrium is a unique observation. Besides morphology, it obviously can share molecular features of sporadic MSI colorectal cancers. It can be speculated that either CDX2 positive morula formation or intestinal metaplasia of the endometrium as rare conditions might be the origin of carcinogenesis for this type II endometrial cancer. Both conditions were not detectable in this case. Of note, categorising endometrial cancers in genetic subgroups like MSI high cancers alone might lead to the integration of likewise morphologically different tumours like the case presented here with intestinal differentiation. Hence, careful genotype-phenotype correlations are warranted for studies of mucinous adenocarcinoma of the endometrium.

Electronic supplementary material

The online version of this article (doi:10.1186/s13000-017-0629-0) contains supplementary material, which is available to authorized users.

Practical Applications in Immunohistochemistry: Carcinomas of Unknown Primary Site

CONTEXT

-Identification of the site of origin of carcinoma of unknown primary using immunohistochemistry is a frequent requirement of anatomic pathologists. Diagnostic accuracy is crucial, particularly in the current era of targeted therapies and smaller sample sizes.

OBJECTIVES

-To provide practical guidance and suggestions for classifying carcinoma of unknown primary using both proven and new antibodies, as well as targeting panels based on integration of morphologic and clinical features.

DATA SOURCES

-Literature review, the authors' practice experience, and authors' research.

CONCLUSIONS

-With well-performed and interpreted immunohistochemistry panels, anatomic pathologists can successfully identify the site of origin of carcinoma of unknown primary. It is crucial to understand not only the diagnostic uses of the many available antibodies but also the potential limits and pitfalls.

Immunohistochemistry in undifferentiated neoplasm/tumor of uncertain origin

CONTEXT

Immunohistochemistry has become an indispensable ancillary study in the identification and classification of undifferentiated neoplasms/tumors of uncertain origin. The diagnostic accuracy has significantly improved because of the continuous discoveries of tissue-specific biomarkers and the development of effective immunohistochemical panels.

OBJECTIVES

To identify and classify undifferentiated neoplasms/tumors of uncertain origin by immunohistochemistry.

DATA SOURCES

Literature review and authors' research data and personal practice experience were used.

CONCLUSIONS

To better guide therapeutic decisions and predict prognostic outcomes, it is crucial to differentiate the specific lineage of an undifferentiated neoplasm. Application of appropriate immunohistochemical panels enables the accurate classification of most undifferentiated neoplasms. Knowing the utilities and pitfalls of each tissue-specific biomarker is essential for avoiding potential diagnostic errors because an absolutely tissue-specific biomarker is exceptionally rare. We review frequently used tissue-specific biomarkers, provide effective panels, and recommend diagnostic algorithms as a standard approach to undifferentiated neoplasms.

Cadherin-17 and SATB2 are sensitive and specific immunomarkers for medullary carcinoma of the large intestine

CONTEXT

Distinction of medullary carcinoma of the large intestine from other cytokeratin (CK) 7⁻/CK20⁻ carcinomas can be challenging when working on a tumor of unknown primary because the majority of medullary carcinomas are negative for CK7, CK20, and CDX2.

OBJECTIVE

To investigate the expression of cadherin-17 and SATB-2 and other markers in medullary carcinomas of the large intestine and cadherin-17 and SATB2 in a large number of carcinomas and normal tissues from various organs to further test their diagnostic specificity.

DESIGN

This study evaluated cadherin-17 and SATB2 expression in 18 medullary carcinoma cases and 1941 tumors and 358 normal tissues from various organs. Other immunomarkers, including MLH1, PMS2, MSH2, MSH6, CDX2, CK7, CK20, TFF3, MUC4, calretinin, p504S, villin, and synaptophysin, were also tested on the 18 medullary carcinoma cases.

RESULTS

The results demonstrated (1) loss of MLH1 and PMS2 in more than 80% of medullary carcinomas; (2) expression of cadherin-17 and SATB2 in 89% of medullary carcinomas; (3) focal expression of TFF3, MUC4, calretinin, CDX2, CK20, and synaptophysin in 72%, 72%, 67%, 67%, 28%, and 17% of 18 medullary carcinoma cases, respectively; and (4) expression of SATB2 and cadherin-17 in 97% and 98% of the colorectal adenocarcinomas, respectively, whereas their expression was seen in 3.6% and 3.3% of nongastrointestinal tumors, respectively.

CONCLUSION

We concluded that SATB2 and cadherin-17 were highly sensitive and specific markers for colorectal carcinomas and propose including MLH1, cadherin-17, and SATB2 in a routine immunostaining panel when working on a tumor of unknown primary, especially in an elderly patient with a CK7⁻/CK20⁻ carcinoma.

Primary Squamous Cell Carcinoma of the Upper Genital Tract: Utility of p16(INK4a) Expression and HPV DNA Status in its Differential Diagnosis from Extended Cervical Squamous Cell Carcinoma

BACKGROUND

Primary squamous cell carcinoma (SCC) of the upper genital tract, including the endometrium, fallopian tubes, and ovaries, is extremely rare. It must be distinguished from the mucosal extension of primary cervical SCC because determination of the primary tumor site is important for tumor staging. However, patients with SCC of the fallopian tubes or ovarian surface have often undergone prior hysterectomy with inadequate examination of the cervix, making it difficult to determine the primary site.

METHODS

We compared histologic findings, p16(INK4a) expression, and human papillomavirus (HPV) DNA status in four patients with primary SCC of the upper genital tract and five patients with primary cervical SCC extending to the mucosa of the upper genital tract.

RESULTS

All five SCCs of cervical origin showed strong expression of p16(INK4a), whereas all four SCCs of the upper genital tract were negative, although one showed weak focal staining. Three of the five cervical SCCs were positive for HPV16 DNA, whereas all four primary SCCs of the upper genital tract were negative for HPV DNA.

CONCLUSIONS

Although a thorough histological examination is important, immunonegativity for p16(INK4a) and negative for HPV DNA may be useful adjuncts in determining primary SCCs of the upper genital tract.

Demonstration of CDX2 is highly antibody dependant

OBJECTS

CDX2 is a widely used immunohistochemical marker for intestinal differentiation in neoplasms. In the Nordic Immunohistochemical Quality Control external quality assessment scheme, only 45% of the laboratories participating in the CDX2 challenge in 2009 produced sufficient staining. A major cause of insufficient staining results appeared to be less successful primary antibody (Ab) clones. To evaluate the Ab performance in a standardized way, a comparative study was carried out.

MATERIALS AND METHODS

Tissue microarrays containing 309 non-neoplastic tissues and tumor samples with expected high, low, and no CDX2 expression were used. Five Abs were selected for comparison: EPR2764Y concentrated (Conc), EPR2764Y in a ready-to-use format, and DAK-CDX2, AMT28, and CDX2-88, all Conc. The CDX2 stains were scored blindly using the H-score method. Tissue/tumor samples with a maximum H-score of 150 to 300 (on the basis of the staining giving the highest score) were classified as CDX2 high expressors, samples with a maximum H-score of 10 to 149 as low expressors, and samples with a maximum H-score <10 as negative.

RESULTS AND CONCLUSIONS

A total of 106 tumors were CDX2 positive with at least one of the Abs. For 56 high-expressor tumors, the mean H-scores with EPR2764Y Conc, EPR2764Y ready-to-use, DAK-CDX2, AMT28, and CDX2-88 were 262, 236, 234, 167, and 149, respectively, and the percentage of positive tumors 100, 100, 100, 98, and 93, respectively. For 50 low-expressor tumors, the mean H-scores with the same Abs were 59, 26, 28, 7, and 5, respectively, and the percentage of positive tumors 98, 58, 64, 18, and 14, respectively. With EPR2764Y Conc, CDX2 was demonstrated in 5/19 (26%) urothelial carcinomas, 7/64 (11%) lung adenocarcinomas, 5/30 (17%) large cell/sarcomatoid lung carcinomas, and 4/19 (21%) esophagus squamous cell carcinomas. In-house optimized protocols gave for all 4 Conc Abs better staining results than the vendors' recommended protocols. The sensitivity of CDX2 Abs and protocols must be taken into consideration when classifying neoplasms of unknown origin.

Immunohistochemistry of colorectal carcinoma: current practice and evolving applications

The relatively high incidence of adenocarcinoma of the colon and rectum (colorectal carcinoma) in the general population makes its pathologic diagnosis one of the more frequent exercises in anatomical pathology. Although typically mundane in the primary setting, the correct identification of metastatic colorectal carcinoma or exclusion of metastatic disease from carcinoma arising in other anatomical foci can be problematic. The advent of targeted therapies and refinement of more traditional cytotoxic chemotherapeutic regimens mandates not only a more confident appraisal of site of origin but also assessment of those tumor-specific features that may alter therapeutic decisions. Despite the exponential increase in our understanding of the molecular pathogenesis of colorectal carcinoma, immunohistochemistry remains the foundation for resolution of these problematic cases and the number of antibodies available to the practicing pathologist continues to expand at a steady rate. In some cases, immunohistochemistry may also provide valuable prognostic information, either independently or as a surrogate marker for a specific route of carcinogenesis such as microsatellite instability. This review will focus on the use of new and more established immunohistochemistry markers in the diagnosis of colorectal carcinoma, with an emphasis on aberrant staining patterns of the various colorectal carcinoma subtypes as well as the utility of these markers in specific differential diagnostic settings.

CDX-2 expression in malignant germ cell tumors of the testes, intratubular germ cell neoplasia, and normal seminiferous tubules

CDX-2 is a caudal-type homeobox gene, encoding a transcription factor that plays an important role in proliferation and differentiation of intestinal epithelial cells. The utility of antibodies to CDX2 in the identification of adenocarcinomas of the gastrointestinal tract, particularly colorectal adenocarcinomas, in both primary and metastatic settings is well established. It is well-known that patients with testicular tumors may occasionally lack an obvious palpable mass. However, the expression of CDX2 in malignant germ cell tumors of the testes which have metastatic potential has not been previously studied in a large series. A tissue microarray was constructed from 52 malignant germ cell tumors of the testes including: 29 cases of classic seminoma, 8 cases of embryonal carcinoma, 8 cases of yolk sac tumor, 4 cases of malignant teratoma, 2 cases of choriocarcinoma, and 1 case of spermatocytic seminoma. Ten cases of intratubular germ cell neoplasia and seven cases of benign testicles with normal seminiferous tubules were also included in tissue microarray. Immunohistochemical stains for CDX2 was performed and analyzed. Only nuclear staining was considered positive. Positive expression of CDX2 was identified in 2/2 cases (100 %) of choriocarcinoma, 4/8 cases (50 %) of teratoma, 3/8 cases (38 %) of embryonal carcinoma, 3/8 cases (38 %) of yolk sac tumor, and 1/29 cases (3 %) of classic seminoma. CDX2 was negative in all cases of intratubular germ cell neoplasia, normal seminiferous tubules, and the only case of spermatocytic seminoma. The role of CDX-2 in the differentiation of intestinal/enteric epithelial cells may contribute to the formation of trophoblastic, glandular, villous, or cystic structures in germ cell tumors of the testes. This study suggests that the expression of CDX2 in a variety of malignant germ cell tumors of the testes may be a potential pitfall in metastatic tumors of unknown primary, which are thought to be of gastrointestinal/colorectal origin but are actually from a clinically occult testicular tumor.

Tissue-specific cadherin CDH17 is a useful marker of gastrointestinal adenocarcinomas with higher sensitivity than CDX2

Cadherin 17 (CDH17) is a cell adhesion molecule expressed in intestinal epithelium and transcriptionally regulated by CDX2. We compared the usefulness of CDH17 as an immunohistochemical intestinal marker to that of CDX2 in gastrointestinal and extragastrointestinal carcinomas and nonneoplastic tissues. Nonneoplastic intestinal and pancreatic duct epithelia were CDH17-positive. Most esophageal (79%), gastric (86%), and colonic (99%) adenocarcinomas were CDH17-positive/CDX2-positive, whereas 1% of colonic, 18% of esophageal, and 10% of gastric adenocarcinomas were CDH17-negative/CDX2-negative. Rare colonic, esophageal, and gastric adenocarcinomas were CDH17-positive/CDX2-negative (1%, 3%, and 4%, respectively), and none were CDH17-negative/CDX2-positive. Diffuse CDH17 was also observed in all metastatic colon carcinomas, 20% of which were only focally CDX2-positive. Of intestinal low-grade neuroendocrine tumors, 74% coexpressed CDX2 and CDH17. CDH17 was also positive in 12% of pancreatic and 24% of bronchial neuroendocrine tumors, all of which were CDX2-negative. Pancreatic adenocarcinomas and cholangiocarcinomas were more frequently CDH17-positive than CDX2-positive (50% vs 27%, 53% vs 27%). One (2%) hepatocellular carcinoma was CDH17-positive/CDX2-negative. Nine percent of non-small cell lung cancers and 7% of endometrial carcinomas were CDH17-positive, whereas 3% of lung, 5% of endometrial, 3% of ovarian, and 2% of breast carcinomas were CDX2-positive. Thus, CDH17 is slightly more sensitive than CDX2 when detecting gastrointestinal adenocarcinomas.