Value of PAX2 immunostaining in tumor diagnosis: a review and update

Single-Cell and Transcriptome-Based Immune Cell-Related Prognostic Model in Clear Cell Renal Cell Carcinoma

Traditional studies mostly focus on the role of single gene in regulating clear cell renal cell carcinoma (ccRCC), while it ignores the impact of tumour heterogeneity on disease progression. The purpose of this study is to construct a prognostic risk model for ccRCC by analysing the differential marker genes related to immune cells in the single-cell database to provide help in clinical diagnosis and targeted therapy. Single-cell data and ligand-receptor relationship pair data were downloaded from related publications, and ccRCC phenotype and expression profile data were downloaded from TCGA and CPTAC. Based on the DEGs of each cluster acquired from single-cell data, immune cell marker genes, and ligand-receptor gene data, we constructed a multilayer network. Then, the genes in the network and the genes in TCGA were used to construct the WGCNA network, which screened out prognosis-associated genes for subsequent analysis. Finally, a prognostic risk scoring model was obtained, and CPTAC data showed that the effectiveness of this model was good. A nomogram based on the predictive model for predicting the overall survival was established, and internal validation was performed well. Our findings suggest that the predictive model built and based on the immune cell scRNA-seq will enable us to judge the prognosis of patients with ccRCC and provide more accurate directions for basic relevant research and clinical practice.

Metastases to the Thyroid: Potential Cytologic Mimics of Primary Thyroid Neoplasms

Secondary tumors of the thyroid gland, although uncommon, can sometimes pose as diagnostic dilemmas on fine-needle aspiration cytology, frequently mimicking primary thyroid neoplasms. An accurate diagnosis of such lesions, however, is critical for patient management and prognosis. The present study reviews the cytologic aspects of secondary involvement of the thyroid, listing the most common primary malignancies that metastasize to this gland. Knowledge of such morphologic aspects, combined with prompt clinical correlation, is essential for the cytopathologist to achieve a proper, definite diagnosis.

Emerging entities in renal cell neoplasia: thyroid-like follicular renal cell carcinoma and multifocal oncocytoma-like tumours associated with oncocytosis

The list of accepted entities of renal cell neoplasia has burgeoned since the turn of the century through recognition of rare tumour types and the discovery of genetic mutations driving renal neoplasia syndromes. This growth has not finished and in this report we present examples of each of these types which were not included in the 2016 World Health Organization classification of renal neoplasia, but are candidates for inclusion in the next edition of the classification. Thyroid-like follicular renal cell carcinoma is a rare tumour type with a distinctive microscopic appearance resembling follicles of the thyroid gland. Thirty-nine cases have been described and the findings have been reasonably consistent. Oncocytoma-like tumours associated with oncocytosis arise as a result of somatic mutations in the mitochondrial genome. The differential diagnosis is mainly with the renal lesions of the Birt-Hogg-Dubé syndrome, which is the result of germline mutations in the folliculin gene. Patients with oncocytoma-like tumours associated with oncocytosis are at great risk of developing renal failure as the proliferating lesions replace the renal parenchyma. Oncocytoma-like tumours have never been found to metastasise.

A systematic search strategy identifies cubilin as independent prognostic marker for renal cell carcinoma

BACKGROUND

There is an unmet clinical need for better prognostic and diagnostic tools for renal cell carcinoma (RCC).

METHODS

Human Protein Atlas data resources, including the transcriptomes and proteomes of normal and malignant human tissues, were searched for RCC-specific proteins and cubilin (CUBN) identified as a candidate. Patient tissue representing various cancer types was constructed into a tissue microarray (n = 940) and immunohistochemistry used to investigate the specificity of CUBN expression in RCC as compared to other cancers. Two independent RCC cohorts (n = 181; n = 114) were analyzed to further establish the sensitivity of CUBN as RCC-specific marker and to explore if the fraction of RCCs lacking CUBN expression could predict differences in patient survival.

RESULTS

CUBN was identified as highly RCC-specific protein with 58% of all primary RCCs staining positive for CUBN using immunohistochemistry. In venous tumor thrombi and metastatic lesions, the frequency of CUBN expression was increasingly lost. Clear cell RCC (ccRCC) patients with CUBN positive tumors had a significantly better prognosis compared to patients with CUBN negative tumors, independent of T-stage, Fuhrman grade and nodal status (HR 0.382, CI 0.203-0.719, P = 0.003).

CONCLUSIONS

CUBN expression is highly specific to RCC and loss of the protein is significantly and independently associated with poor prognosis. CUBN expression in ccRCC provides a promising positive prognostic indicator for patients with ccRCC. The high specificity of CUBN expression in RCC also suggests a role as a new diagnostic marker in clinical cancer differential diagnostics to confirm or rule out RCC.

A Detailed Immunohistochemical Analysis of a Large Series of Cervical and Vaginal Gastric-type Adenocarcinomas

Adenocarcinomas exhibiting gastric differentiation represent a recently described and uncommon subtype of non-human papillomavirus (HPV)-related cervical adenocarcinoma. They comprise a spectrum from a well-differentiated variant (adenoma malignum/mucinous variant of minimal deviation adenocarcinoma) to a more poorly differentiated overtly malignant form, generally referred to as gastric-type adenocarcinoma. Rarely, such tumors have also been described as primary vaginal neoplasms. Gastric-type adenocarcinomas exhibit considerable morphologic overlap with adenocarcinomas originating outside the female genital tract, especially mucinous adenocarcinomas arising in the pancreas and biliary tract. Moreover, they often metastasize to unusual sites, such as the ovary and peritoneum/omentum, where they can be mistaken for metastatic adenocarcinomas from other, nongynecologic sites. There is little information regarding the immunophenotype of gastric-type adenocarcinomas, and knowledge of this is important to aid in the distinction from other adenocarcinomas. In this study, we undertook a detailed immunohistochemical analysis of a large series of cervical (n=45) and vaginal (n=2) gastric-type adenocarcinomas. Markers included were cytokeratin (CK)7, CK20, CDX2, carcinoembryonic antigen, CA125, CA19.9, p16, estrogen receptor, progesterone receptor, MUC6, PAX8, PAX2, p53, hepatocyte nuclear factor 1 beta, carbonic anhydrase IX, human epidermal receptor 2 (HER2), and mismatch repair (MMR) proteins. All markers were classified as negative, focal (<50% of tumor cells positive), or diffuse (≥50% tumor cells positive) except for p53 (classified as "wild-type" or "mutation-type"), HER2 (scored using the College of American Pathologists guidelines for gastric carcinomas), and MMR proteins (categorized as retained or lost). There was positive staining with CK7 (47/47-45 diffuse, 2 focal), MUC6 (17/21-6 diffuse, 11 focal), carcinoembryonic antigen (25/31-12 diffuse, 13 focal), carbonic anhydrase IX (20/24-8 diffuse, 12 focal), PAX8 (32/47-20 diffuse, 12 focal), CA125 (36/45-5 diffuse, 31 focal), CA19.9 (11/11-8 diffuse, 3 focal), hepatocyte nuclear factor 1 beta (13/14-12 diffuse, 1 focal), CDX2 (24/47-4 diffuse, 20 focal), CK20 (23/47-6 diffuse, 17 focal), and p16 (18/47-4 diffuse, 14 focal). Most cases were negative with estrogen receptor (29/31), progesterone receptor (10/11), PAX2 (18/19), and HER2 (25/26). p53 showed "wild-type" and "mutation-type" staining in 27 of 46 and 19 of 46 cases, respectively. MMR protein expression was retained in 19 of 20 cases with loss of MSH6 staining in 1 patient with Lynch syndrome. Molecular studies for HPV were undertaken in 2 tumors, which exhibited diffuse "block-type" immunoreactivity with p16, and both were negative. This is the first detailed immunohistochemical study of a large series of gastric-type adenocarcinomas of the lower female genital tract. Our results indicate immunophenotypic overlap with pancreaticobiliary adenocarcinomas but suggest that PAX8 immunoreactivity may be especially useful in distinguishing gastric-type adenocarcinomas from pancreaticobiliary and other nongynecologic adenocarcinomas, which are usually negative. Diffuse "block-type" p16 immunoreactivity in a cervical adenocarcinoma is not necessarily indicative of a high-risk HPV-associated tumor.

Differential patterns of PAX8, p16, and ER immunostains in mesonephric lesions and adenocarcinomas of the cervix

Mesonephric remnants, usually located deep in the lateral cervical wall, may become hyperplastic resulting in a florid proliferation. These can be misinterpreted as malignant and confused with endocervical adenocarcinomas. Recent data have shown that PAX2 is diffusely expressed in mesonephric remnants and hyperplasias. PAX8 is a related transcription protein that is expressed in tissues of müllerian and wolffian origin. In this study, we have investigated the utility of an immunohistochemical panel comprising of PAX8, estrogen receptor (ER), and p16 in the differential diagnosis between mesonephric proliferations and cervical adenocarcinomas. A database search was conducted for cases of mesonephric remnants/hyperplasia/carcinoma of cervix and invasive cervical adenocarcinomas. Immunohistochemical stains for PAX8, ER, and p16 were performed using the avidin-biotin peroxidase technique on the most representative tissue. The search yielded 28 cases of mesonephric proliferations of cervix (15 mesonephric remnants, 12 mesonephric hyperplasias, and 1 mesonephric adenocarcinoma) and 16 cases of cervical adenocarcinomas (15 usual type and 1 adenoma malignum). Immunohistochemically, all the mesonephric proliferations, regardless of being benign or malignant, displayed a consistent staining pattern-diffusely and strongly positive for PAX8, negative for ER, and patchy cytoplasmic staining for p16. The usual type cervical adenocarcinomas exhibited a variable staining pattern with PAX8 and ER but all were strongly and diffusely positive for p16. The case of adenoma malignum was PAX8 positive, ER negative, and showed weak and patchy staining with p16. Our study suggests that a panel of immunohistochemical stains composed of PAX8, p16, and ER is useful in the distinction between mesonephric proliferations and cervical adenocarcinomas.

Metastatic carcinoma of unknown primary: diagnostic approach using immunohistochemistry

Carcinoma of unknown primary origin (CUP) is one of the 10 most prevalent malignancies. CUP patients in whom a site of origin can be ascribed have better outcomes than those in which the primary tumor remains unidentified. Among the tools available to pathologists in approaching these lesions, immunohistochemistry is a reliable, inexpensive, and widely available resource. New markers continue to emerge, which, in combination with other historically useful antibodies, allow rapid and accurate identification of primary site in an increasing number of cases. This review discusses the approach to the diagnosis of CUP using immunohistochemistry and outlines some of the most useful markers with a particular focus on the utility of lineage-restricted transcription factors, including CDX2, NKX3-1, PAX8, SATB2, TTF-1, and SF1.

Value of podoplanin as an immunohistochemical marker in tumor diagnosis: a review and update

Podoplanin is a type I integral membrane glycoprotein that, because it is expressed in lymphatic endothelium, but not in vascular blood vessel endothelial cells, is commonly used in the identification of lymphatic endothelial differentiation in vascular endothelial neoplasms and lymphatic invasion by tumor. Because podoplanin is also expressed in mesothelial cells and fetal gonocytes, it has proved to be a useful marker for assisting in the differential diagnosis of mesotheliomas and germ cell tumors, particularly seminomas/dysgerminomas. Podoplanin expression has also been reported in a wide variety of other neoplasms, including hemangioblastomas, meningiomas, cartilaginous tumors, and follicular dendritic cell neoplasms. This article reviews the information that is currently available on the application of podoplanin immunostaining in diagnostic pathology.

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.

Pax8 and Pax2 are specifically required at different steps of Xenopus pronephros development

The respective role of Pax2 and Pax8 in early kidney development in vertebrates is poorly understood. In this report, we have studied the roles of Pax8 and Pax2 in Xenopus pronephros development using a loss-of-function approach. Our results highlight a differential requirement of these two transcription factors for proper pronephros formation. Pax8 is necessary for the earliest steps of pronephric development and its depletion leads to a complete absence of pronephric tubule. Pax2 is required after the establishment of the tubule pronephric anlage, for the expression of several terminal differentiation markers of the pronephric tubule. Neither Pax2 nor Pax8 is essential to glomus development. We further show that Pax8 controls hnf1b, but not lhx1 and Osr2, expression in the kidney field as soon as the mid-neurula stage. Pax8 is also required for cell proliferation of pronephric precursors in the kidney field. It may exert its action through the wnt/beta-catenin pathway since activation of this pathway can rescue MoPax8 induced proliferation defect and Pax8 regulates expression of the wnt pathway components, dvl1 and sfrp3. Finally, we observed that loss of pronephros in Pax8 morphants correlates with an expanded vascular/blood gene expression domain indicating that Pax8 function is important to delimit the blood/endothelial genes expression domain in the anterior part of the dorso-lateral plate.

Best practices recommendations in the application of immunohistochemistry in the bladder lesions: report from the International Society of Urologic Pathology consensus conference

The bladder working group of the 2013 International Society of Urologic Pathology (ISUP) Conference on Best Practices Recommendation in the Application of Immunohistochemistry (IHC) in Urologic Pathology discussed 5 settings in which IHC is commonly used in clinical practice. With regard to markers for urothelial differentiation, the committee found that there is no ideal marker or established panel to confirm urothelial differentiation. On the basis of the differential diagnostic consideration, positivity for GATA3, CK20, p63, and either high-molecular weight cytokeratin (HMWCK) or cytokeratin (CK)5/6 is of value in proving urothelial differentiation in the appropriate morphologic and clinical context. With regard to the role of IHC in the distinction of reactive atypia from urothelial carcinoma in situ, the committee recommended that morphology remains the gold standard in this differential diagnosis and that, at best, the IHC panel of CK20/p53/CD44(s) has potential utility but is variably used and has limitations. The immunostaining pattern must be interpreted with strict morphologic correlation, because overreliance on IHC may be misleading, particularly in the posttreatment setting. IHC has no role in the distinction of dysplasia versus carcinoma in situ and in the grading of papillary urothelial carcinoma. IHC may have a limited but distinct role in staging of bladder cancer. In a subset of cases, depending on the clinical and histologic context, broad-spectrum cytokeratins (to identify early or obscured invasion) and desmin (distinction of muscle from desmoplasia and to highlight muscle contours for subclassification) may be helpful. Limited experience and conflicting data preclude smoothelin or vimentin to be recommended routinely for subclassifying muscle type at this time. In the workup of a spindled cell proliferation of the bladder and in limited specimens, we recommend an immunohistochemical panel of 6 markers including ALK1, SMA, desmin, cytokeratin (AE1/AE3), and p63 with either of HMWCK or CK5/6. Currently, there are no prognostic immunohistochemical or molecular studies that are recommended to be routinely performed on biopsy or resection specimens.

Diagnostic utility of immunohistochemistry in distinguishing between epithelioid pleural mesotheliomas and breast carcinomas: a comparative study

Epithelioid mesotheliomas and breast carcinomas can present a variety of morphologic patterns. Because of this, breast carcinomas that metastasize to the pleura and lung may be confused with mesotheliomas. The aim of the present study is to compare the immunohistochemical markers currently available for the diagnosis of these 2 malignancies and to determine the best panel of markers that can be used to assist in discriminating between them. Sixty epithelioid mesotheliomas and 80 breast carcinomas (40 triple negative and 40 estrogen receptor positive) were investigated for expression of the positive mesothelioma markers calretinin, keratin 5/6, mesothelin, podoplanin, thrombomodulin, and WT1; the positive carcinoma marker claudin 4; and the breast-associated markers gross cystic disease fluid protein 15 (GCDFP-15), mammaglobin, and GATA3. All of the epithelioid mesotheliomas reacted for calretinin and keratin 5/6, 93% for WT1; 88% for podoplanin; 77% for thrombomodulin; 23% for GATA3; and 0% for claudin 4, GCDFP-15, and mammaglobin, respectively. Of the triple-negative breast carcinomas, 100% expressed claudin 4; 5%, keratin 5/6; 30%, GATA3; 18%, mammaglobin; 15%, GCDFP-15; 56%, mesothelin; 38%, calretinin; 18%, thrombomodulin; 5%, WT1; and 3%, podoplanin. Among the estrogen receptor-positive breast carcinomas, 100% were claudin 4 and GATA3 positive; 70% expressed GCDFP-15; 63%, mammaglobin; 13%, calretinin; 13%, thrombomodulin; 8%, WT1; 5%, keratin 5/6; 3%, mesothelin; and 0%, podoplanin. It is concluded that podoplanin and WT1 are the best positive mesothelioma markers for differentiating epithelioid mesotheliomas from breast carcinomas. An accurate differential diagnosis can be reached with the use of these two markers in combination with the breast-associated markers GCDFP-15, mammaglobin, and GATA3.

Value of PAX8, PAX2, napsin A, carbonic anhydrase IX, and claudin-4 immunostaining in distinguishing pleural epithelioid mesothelioma from metastatic renal cell carcinoma

Both mesotheliomas and renal cell carcinomas can present a wide variety of cytomorphologic features and histologic patterns. Because of this, renal cell carcinomas metastatic to the pleura and lung can be confused with mesotheliomas. Recently, a variety of positive carcinoma markers, including kidney-associated markers, have become available. The aim of this study is to investigate the value of some of these markers, specifically PAX8, PAX2, napsin A, carbonic anhydrase IX, and claudin-4, for assisting in distinguishing pleural epithelioid mesotheliomas from metastatic renal cell carcinomas. To do so, a total of 40 pleural epithelioid mesotheliomas and 55 renal cell carcinomas (33 clear cell, 10 papillary, and 12 chromophobe) were investigated. In all, 91% of the renal cell carcinomas expressed claudin-4, 89% PAX8, 60% PAX2, 71% carbonic anhydrase IX, and 29% napsin A. All of the mesotheliomas were positive for carbonic anhydrase IX and were negative for all of the other markers. On the basis of these results, it is concluded that claudin-4 and PAX8 have a higher sensitivity and specificity for assisting in discriminating between pleural epithelioid mesotheliomas and renal cell carcinomas when compared with all of the other positive carcinoma markers that are, at present, recommended to be included in the immunohistochemical panels used in this differential diagnosis. Even though PAX2 and napsin A are highly specific, because of their low sensitivity, they have only a limited value. Carbonic anhydrase IX is not useful.

Value of PAX8, PAX2, claudin-4, and h-caldesmon immunostaining in distinguishing peritoneal epithelioid mesotheliomas from serous carcinomas

Distinguishing between peritoneal epithelioid mesotheliomas and papillary serous carcinomas involving the peritoneum can be difficult on routine histological preparations, but this differential diagnosis can be facilitated by the use of immunohistochemistry. Recent investigations have indicated that PAX8, PAX2, claudin-4, and h-caldesmon are immunohistochemical markers that can assist in distinguishing between these two malignancies; however, much of the information published on the value of these markers is either insufficient or contradictory. The purpose of this study is to resolve some of the existing controversies and to fully determine the practical value of these markers for assisting in the differential diagnosis between peritoneal mesotheliomas and serous carcinomas. In order to do so, a total of 40 peritoneal epithelioid mesotheliomas and 45 serous carcinomas (15 primary, 30 metastatic to the peritoneum) were investigated. PAX8 and PAX2 nuclear positivity was demonstrated in 42 (93%) and 25 (56%) of the serous carcinomas, respectively, whereas none of the mesotheliomas expressed either marker. Forty-four (98%) of the serous carcinomas exhibited claudin-4 reactivity along the cell membrane, whereas none of the mesotheliomas were positive for this marker. All of the serous carcinomas and mesotheliomas were negative for h-caldesmon. Based on these results, it is concluded that PAX8 and claudin-4 have a higher sensitivity and specificity for assisting in discriminating between peritoneal epithelioid mesotheliomas and serous carcinomas when compared with all of the other positive carcinoma markers that are, at present, recommended to be included in the immunohistochemical panels used in this differential diagnosis. Even though it is highly specific, PAX2 has little practical value in the diagnosis of peritoneal epithelioid mesotheliomas as its sensitivity is low. The h-caldesmon is not useful.