Diagnostic utility of PAX8 and PAX2 immunohistochemistry in the identification of metastatic Müllerian carcinoma in effusions

Clinical significance of CD8-positive lymphocytes on tumor cell clusters of ascites cell block in ovarian high-grade serous carcinoma

Background

The clinical significance of CD8‐positive (CD8⁺) lymphocytes on tumor cell clusters of ascites cell blocks in patients with ovarian high‐grade serous carcinoma (HGSC) was investigated.

Methods

Among HGSC patients who underwent surgery from January 2014 to December 2019, 38 patients with ascites cell block were selected. Using these cell blocks and primary ovarian tumor tissue, the presence of CD8⁺ lymphocytes and the expression of PD‐L1 were examined immunohistochemically. Tumor cell clusters were defined as cell clumps consisting of more than 10 malignant cells in cell block. Cases with at least one CD8⁺ lymphocyte in tumor cell cluster were defined as positive CD8⁺ lymphocytes (Group A); others were defined as negative CD8⁺ lymphocytes (Group B). The tumor tissue CD8⁺ lymphocytes were counted mechanically. Clinicopathological features were retrospectively compared between the two groups.

Results

In total, 38 cases were identified: 25 (65.8%) in Group A and 13 (34.2%) in Group B. More cases in Group A were positive for CD4 (p < 0.01), PD‐L1 (p = 0.02), FoxP3 (p = 0.02) and had a higher number of CD8⁺ lymphocytes in the tissue (p = 0.03). Patients in Group A had better progression‐free survival (p < 0.01) and overall survival (p = 0.04). In multivariate analysis, Group A was an independent prognostic factor for both progression‐free survival (hazard ratio, 0.24; p < 0.01) and overall survival (hazard ratio, 0.21; p = 0.03).

Conclusion

The presence of CD8⁺ lymphocytes in tumor cell clusters of ascites was associated with the status of immune reaction in the tissue and prognosis in patients with HGSC and might be useful information of the immune‐associated therapy.

Diagnostic efficacy of ascites cell block for ovarian clear cell carcinoma

BACKGROUND

Ascites cytology is important for determining the stage and treatment methods for ovarian clear cell carcinoma (CCC) as defined by the 2014 International Federation of Obstetrics and Gynecology classification.

METHODS

Patients with CCC who underwent surgery at our hospital between January 2012 and December 2019 and who received cytodiagnosis of their ascites using Papanicolaou (Pap) and May-Grünwald-Giemsa (MGG) staining, and cell block methods were identified. The cell block technique was performed using hematoxylin-eosin (H&E) staining and immunohistochemical staining for hepatocyte nuclear factor-1β (HNF-1β), estrogen receptor (ER), progesterone receptor (PR), and Wilms tumor-1 (WT-1). Cancer cells of CCC were defined as tumor cells that were positive for HNF-1β and negative for ER, PR, and WT-1. The diagnostic accuracy of ascites cytology using Pap and MGG staining and cell block methods was examined.

RESULTS

Based on cytological data, our study included 17 patients: seven (41.1%) with malignant (MAL) ascites, eight (47.1%) with negative for malignancy (NFM), and two (11.8%) with atypia of undetermined significance (AUS) because of a few atypical cells based on Pap and MGG staining. Malignant cells diagnosed by cell blocks were detected in 7/7 patients with MAL ascites based on PAP and MGG staining, 2/8 (25.0%) patients with NFM, and 1/2 (50%) patients with AUS.

CONCLUSION

These findings show that the cell block method combined with the immunohistochemical investigation may be useful for increasing the diagnostic accuracy of malignant cells in CCC.

Immunochemistry in the work-up of mesothelioma and its differential diagnosis and mimickers

The differential diagnosis in cellular effusions with cytological atypia often includes malignant mesothelioma (MM), reactive mesothelial proliferation, and malignancies of metastatic origin, particularly carcinomas. The International Reporting System for Serous Fluid recently established guidelines for reporting MM. In conjunction with the cytomorphologic evaluation, the role of immunochemistry (IC) was emphasized as a very useful tool in the workup of serous fluids, especially with the availability of novel markers. Utilizing a panel of markers, IC allows the characterization of the cells, whether mesothelial or not, and when mesothelial origin is established, IC can frequently assist in delineating its benign or malignant nature. IC can also confirm metastatic disease, allowing the identification of the primary origin in most cases. This review summarizes the current status of IC and its role in the diagnosis of MM and its differential diagnosis in serous fluids.

Morphologic and Immunocytochemical Features of High-Grade Serous Carcinoma of Ovary in Ascitic Fluid Effusion and Fine-Needle Aspiration Cytology

OBJECTIVES

High-grade serous carcinoma (HGSC) is the most common ovarian malignancy. The role of cytopathology in obtaining tissue diagnosis before institution of neoadjuvant chemotherapy (NACT) was evaluated.

METHODS

All histopathology-proven HGSC specimens between 2015 and 2018 with prior cytopathologic diagnosis by ascitic fluid evaluation or fine-needle aspiration (FNA) of ovarian mass were reviewed with cell block immunocytochemistry for CK7, CK20, PAX8, WT1, and p53.

RESULTS

Of 288 cases of HGSC, pre-NACT cytology diagnosis was established in 32% (93/288), with specific HGSC diagnoses made on ascitic fluid in 88% (82/93) and by ovarian mass FNA in 12% (11/93). The ascitic fluid showed moderate/high cellularity with papillary clusters in 76% (71/93) cases. Cell block immunocytochemistry showed tumor cells positive for CK7, PAX8, and WT1. p53 showed mutant or null-type positivity in 65% (33/51) and 33% (17/51) of cases, respectively, with 100% concordance with subsequent histopathology specimens. Poor/intermediate response to chemotherapy was shown in 75% of cases.

CONCLUSIONS

Combined assessment of cytomorphology, cell block histomorphology, and ancillary immunohistochemical testing, including PAX8, WT1, and p53, allows for specific pre-NACT diagnoses of HGSC in ascitic fluid and ovarian FNA cytology. This practice allows for initiation of chemotherapy and diminution of disease burden prior to definitive surgical therapy.

An Algorithmic Immunohistochemical Approach to Define Tumor Type and Assign Site of Origin

Immunohistochemistry represents an indispensable complement to an epidemiology and morphology-driven approach to tumor diagnosis and site of origin assignment. This review reflects the state of my current practice, based on 15-years' experience in Pathology and a deep-dive into the literature, always striving to be better equipped to answer the age old questions, "What is it, and where is it from?" The tables and figures in this manuscript are the ones I "pull up on the computer" when I am teaching at the microscope and turn to myself when I am (frequently) stuck. This field is so exciting because I firmly believe that, through the application of next-generation immunohistochemistry, we can provide better answers than ever before. Specific topics covered in this review include (1) broad tumor classification and associated screening markers; (2) the role of cancer epidemiology in determining pretest probability; (3) broad-spectrum epithelial markers; (4) noncanonical expression of broad tumor class screening markers; (5) a morphologic pattern-based approach to poorly to undifferentiated malignant neoplasms; (6) a morphologic and immunohistochemical approach to define 4 main carcinoma types; (7) CK7/CK20 coordinate expression; (8) added value of semiquantitative immunohistochemical stain assessment; algorithmic immunohistochemical approaches to (9) "garden variety" adenocarcinomas presenting in the liver, (10) large polygonal cell adenocarcinomas, (11) the distinction of primary surface ovarian epithelial tumors with mucinous features from metastasis, (12) tumors presenting at alternative anatomic sites, (13) squamous cell carcinoma versus urothelial carcinoma, and neuroendocrine neoplasms, including (14) the distinction of pheochromocytoma/paraganglioma from well-differentiated neuroendocrine tumor, site of origin assignment in (15) well-differentiated neuroendocrine tumor and (16) poorly differentiated neuroendocrine carcinoma, and (17) the distinction of well-differentiated neuroendocrine tumor G3 from poorly differentiated neuroendocrine carcinoma; it concludes with (18) a discussion of diagnostic considerations in the broad-spectrum keratin/CD45/S-100-"triple-negative" neoplasm.

Paired box 2 promotes progression of endometrial cancer via regulating cell cycle pathway

Background: Human paired box 2 (PAX2) plays a key role in cell fate, early patterning and organogenesis.

Methods: We investigated the function of PAX2 on the biological behavior of endometrial cancer in vitro and in vivo and to explore the regulation mechanism, stable knocking-down and over-expression PAX2 endometrial cancer cell lines were established. CCK-8 and transwell assays were applied to determine proliferation, invasion and migration ability. Cell cycle distribution was analyzed by flow cytometry. Affymetrix GeneChip® human Exon 1.0 ST arrays was used to screen the downstream target genes of PAX2.

Results: PAX2 significantly enhanced proliferation and invasiveness. In addition, PAX2 influenced the expression of cyclin-dependent kinase 1(CDK1), which play pivotal roles in cell cycle pathway. When CDK1 was knocked down, and the cell proliferation promotion role of PAX2 was attenuated dramatically to a level comparable with the control groups.

Conclusions: PAX2, though influencing the expression of CDK1, promotes the proliferation, enhances the mobility of endometrial cancer cells, thus exerts an important role in the carcinogenesis of endometrial cancer. PAX2 may be a potential therapeutic target for endometrial cancer.

Updates in Effusion Cytology

Effusion cytology plays multiple roles in the management of benign and malignant disease, from primary diagnosis to tissue allocation for ancillary diagnostic studies and biomarker testing of therapeutic targets. This article summarizes recent advances in pleural effusion cytology, with a focus on the practical application of immunohistochemical markers, cytogenetic techniques, flow cytometry, and molecular techniques for the diagnosis and management of primary and secondary neoplasms of the pleura.

Gynecologic Serous Carcinoma: An Immunohistochemical Analysis of Malignant Body Fluid Specimens

CONTEXT.—

Evaluation of fluid specimens involved by serous carcinoma might potentially include PAX8, GATA3, Uroplakin II, SOX2, and SALL4 antibodies. Those markers are commonly employed for diagnosing carcinomas of various types, including urothelial malignancies and germ cell tumors. There have been no comprehensive immunohistochemical studies, to our knowledge, for those markers on fluid specimens involved by serous carcinoma.

OBJECTIVE.—

To evaluate immunohistochemical markers PAX8, GATA3, SOX2, uroplakin II, and SALL4 in the diagnosis of high-grade serous carcinoma in fluid specimens.

DESIGN.—

We examined 113 fluids (96 ascites specimens and 17 pleural fluid specimens) that were positive for carcinoma. Most (94 cases; 83.2%) consisted of high-grade serous carcinoma of Müllerian origin. Nineteen cases of non-high-grade serous carcinoma (including one case of low-grade serous carcinoma) of gynecologic origin were also included as anecdotal data.

RESULTS.—

In 113 fluid specimens with positive results for carcinoma, including nonserous types, 99 (87.6%) had positive results for PAX8, 19 (16.8%) for GATA3; 19 (16.8%) for SOX2, 23 (20.4%) for uroplakin II, and 8 (7.1%) for SALL4. Of 94 fluids (83.2%) involved with high-grade serous carcinoma, 84 (89.4%) had positive results for PAX8, 18 (19.1%) for GATA3, 17 (18.1%) for SOX2, 22 (23.4%) for uroplakin II, and 8 (8.5%) for SALL4. Some of these specimens showed reactivity for more than one immunohistochemical marker.

CONCLUSIONS.—

Most fluids involving high-grade serous carcinoma showed positive results for PAX8, and some cases expressed GATA3, SOX2, uroplakin II, and SALL4. Serous carcinoma in fluids may be positive for immunohistochemical markers not thought of traditionally as associated with gynecologic malignancy, an important consideration in avoiding misdiagnosis.

Utility of GATA-3 in the work-Up of breast adenocarcinoma and its differential diagnosis in serous effusions:: A Cell-Block Microarray Study

BACKGROUND

GATA-3 is a transcription factor involved in human tissue growth and differentiation. It is a potential marker for breast carcinoma origin in metastasis and predictive of good prognosis. We aim to evaluate the role of GATA3 in determining the breast origin of metastatic adenocarcinoma in malignant effusions using immunohistochemistry on cell-block microarray in comparison with ER and PR results.

METHODS

Cell blocks from 100 cases of malignant and reactive serous effusions with confirmed diagnosis were selected; 28 mammary carcinomas, 64 extra-mammary adenocarcinomas (gastrointestinal, pulmonary, gynecologic), and 8 reactive mesothelium proliferation as control. Immunohistochemistry on cell-block microarray was used. Microarray slides were stained for GATA-3, ER and PR. Nuclear staining of >1% was considered positive.

RESULTS

GATA3, ER and PR were positive in 25 (89%), 20 (71%) and 16 (57%) of breast carcinoma cases, respectively. All non-breast cancer cases were negative for GATA-3 with the exception of one Müllerian adenocarcinoma (1.6%). The calculated sensitivity, specificity and positive predictive value (PPV) of GATA3 reactivity in determining the breast origin of metastatic adenocarcinoma was 89.3% (95% CI: 71.7-97.7%), 98.6% (95% CI: 91.6-99.9%) and 96.2% (95% CI: 80.4-99.9%), respectively. GATA3 positivity was associated with ER or PR positivity in 84% of cases.

CONCLUSIONS

GATA3 is a useful marker in determining the breast origin of metastatic adenocarcinoma in malignant serous effusions. Reactivity to GATA3 may indicate good prognosis. Diagn. Cytopathol. 2016;44:731-736. © 2016 Wiley Periodicals, Inc.

Can We Identify Nephrogenic Adenoma in Urine Cytology Specimens? A Study Evaluating Previously Described Cytomorphologic Features in Correlation With PAX8 Immunohistochemical Staining Results

OBJECTIVES

The aim of this study is to determine if the diagnosis of nephrogenic adenoma (NA) can be made on cytologic criteria alone and if pair box gene transcription factor 8 (PAX8) is useful in the diagnosis of NA in daily cytology practice.

METHODS

Cytologic features of NA previously described in a literature were used to identify NA cells in urinary specimens. Subsequently, all cytology and corresponding biopsy specimens were stained with the PAX8 immunohistochemistry stain. The stains were examined; the results were tabulated.

RESULTS

A total of 44 specimens were reviewed (35 with corresponding biopsy specimens diagnosed as NA and nine negative for NA diagnosis on corresponding biopsy specimens). Of them, 14 demonstrated features previously described as NA. None of atypical cells that were morphologically suspicious for NA showed positive staining, whereas all of the corresponding biopsy sections demonstrated nuclear PAX8 positivity. Only rare lymphocytes present in cytology specimens showed nuclear staining with PAX8.

CONCLUSIONS

Assuming that the results of the PAX8 stain performed are accurate at least in most cases, as suggested by the presence of internal positive controls, our study shows that the previously described cytologic features of NA cannot be used as diagnostic criteria, since they are not characteristic for this entity.

Clinically occult primary fallopian tube carcinoma presenting as a malignant pleural effusion

We report the first known case of malignant pleural effusion (MPE) as the sole presenting feature of clinically occult primary fallopian tube carcinoma (PFTC). A 57-year-old healthy woman was admitted with dyspnea. Evaluation demonstrated a right pleural effusion, fluid of which was malignant. The immunohistochemical profile, including negative calretinin, favored metastatic adenocarcinoma over mesothelioma but could not identify the primary tumour site. Pleural biopsy was not pursued as it would not have helped localize the primary. Chest, abdomen and pelvic computed tomography (CT) demonstrated only borderline lymphadenopathy in the left para-aortic lymph node chain that was hypermetabolic on positron emission tomography. Ultrasound and CT showed normal adnexal anatomy. These findings, coupled with an elevated serum CA-125, prompted empiric neoadjuvant chemotherapy targeting epithelial ovarian carcinoma (EOC) followed by surgery, which revealed a tiny left PFTC with negative peritoneal washings. Sampled left para-aortic lymph nodes were positive. The pleural effusion resolved after chemotherapy. Malignant pleural disease without peritoneal involvement is more characteristic of PFTC than of EOC, in which MPE is common but almost always accompanies peritoneal carcinomatosis. The extensive lymphatic supply of the fallopian tube promotes distant metastasis of small, seemingly localized tumours. This case is a reminder that the clinician should not be dissuaded from considering carcinoma of Müllerian origin, especially PFTC, as the cause of a MPE even in the face of normal gynecologic imaging. Appropriately broad immunohistochemical staining and careful attention to even minimal lymphadenopathy can be invaluable in pinpointing the primary tumour site in such patients.

Metastases to the Pancreas Encountered on Endoscopic Ultrasound-Guided, Fine-Needle Aspiration

Metastatic lesions in the pancreas are very uncommon and may be difficult to differentiate from the more commonly encountered primary neoplasms derived from the exocrine and endocrine pancreas because of the significant overlap in clinical presentation, imaging, and cytologic features. Metastasis to the pancreas may occur years after treatment of the primary neoplasm and is often not considered on initial evaluation because of the rarity of such events. The possibility of a metastasis to the pancreas should be entertained in patients with any prior history of malignancy because a proper diagnosis is essential in identifying surgical candidates, or avoiding potentially unnecessary surgery and facilitating triage to more appropriate nonoperative therapy. Herein, we describe intrapancreatic metastases secondary to renal cell carcinoma, melanoma, and lung carcinoma, as documented by cytologic examination of endoscopic ultrasound-guided fine-needle aspiration of the pancreatic masses.

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.

Adenocarcinoma of Mullerian origin: review of pathogenesis, molecular biology, and emerging treatment paradigms

Traditionally, epithelial ovarian, tubal, and peritoneal cancers have been viewed as separate entities with disparate origins, pathogenesis, clinical features, and outcomes. Additionally, previous classification systems for ovarian cancer have proposed two primary histologic groups that encompass the standard histologic subtypes. Recent data suggest that these groupings no longer accurately reflect our knowledge surrounding these cancers. In this review, we propose that epithelial ovarian, tubal, and peritoneal carcinomas represent a spectrum of disease that originates in the Mullerian compartment. We will discuss the incidence, classification, origin, molecular determinants, and pathologic analysis of these cancers that support the conclusion they should be collectively referred to as adenocarcinomas of Mullerian origin. As our understanding of the molecular and pathologic profiling of adenocarcinomas of Mullerian origin advances, we anticipate treatment paradigms will shift towards genomic driven therapeutic interventions.

PAX8 expression in uterine adenocarcinomas and mesonephric proliferations

PAX8 is a useful immunohistochemical marker for the diagnosis of gynecologic tract malignancies. Several studies have described PAX8 expression in a wide variety of epithelial neoplasms, including ovarian and endometrial carcinomas. The goal of this study was to evaluate PAX8 expression in various types of uterine adenocarcinomas and mesonephric proliferations. Ninety-four cases of uterine adenocarcinomas (52 endometrial endometrioid carcinomas, 21 endometrial serous carcinomas, and 21 human papillomavirus-related endocervical carcinomas), 11 cases of benign mesonephric proliferations (remnants/hyperplasia), and normal endometrial and endocervical glandular epithelium in 58 cases were studied. Immunohistochemical staining was performed with the rabbit polyclonal anti-PAX8 antibody. All adenocarcinoma groups demonstrated a high frequency of PAX8 expression but with relatively high variability in the extent of staining among different subtypes. Both serous carcinomas and endometrioid carcinomas were positive in most cases (95% and 96%, respectively), but serous carcinomas displayed a significantly higher level of expression (immunohistochemical composite scores based on combined extent and intensity of expression) compared with endometrioid carcinomas (mean immunohistochemical composite scores: 8.3 vs. 5.3, respectively; P<0.006). Endocervical adenocarcinomas also had a high frequency of PAX8 expression (86% of cases), but the level of expression was significantly less than that of endometrial adenocarcinomas (mean immunohistochemical composite scores: 2.9 vs. 5.3-8.3, respectively; P<0.004). Among benign glandular epithelia, normal endocervical glands exhibited a significantly lower level of expression compared with either normal endometrial glands or benign mesonephric proliferations (mean immunohistochemical composite scores: 2.6 vs. 6.6-11.2, respectively; P<0.0006). We conclude that PAX8 is expressed in the vast majority of uterine adenocarcinomas, including those of both endometrial and endocervical origin, and that the level of expression based on combined extent and intensity is highest in endometrial serous carcinoma and lowest in endocervical adenocarcinoma. However, the high prevalence of PAX8 expression in the various types of uterine adenocarcinomas precludes use of this marker for distinguishing these tumors. In extrauterine sites, PAX8 can serve as a useful marker for adenocarcinomas of uterine origin (also positive in the majority of ovarian carcinomas), being most sensitive for identification of endometrial adenocarcinomas (both serous and endometrioid). The sensitivity for identifying metastatic endocervical adenocarcinomas is likely less and dependent on the degree to which the significantly lower extent of expression in these tumors is maintained in metastatic sites.

Thyroid transcription factors in development, differentiation and disease

Identification of the thyroid transcription factors (TTFs), NKX2-1, FOXE1, PAX8 and HHEX, has considerably advanced our understanding of thyroid development, congenital thyroid disorders and thyroid cancer. The TTFs are fundamental to proper formation of the thyroid gland and for maintaining the functional differentiated state of the adult thyroid; however, they are not individually required for precursor cell commitment to a thyroid fate. Although knowledge of the mechanisms involved in thyroid development has increased, the full complement of genes involved in thyroid gland specification and the signals that trigger expression of the genes that encode the TTFs remain unknown. The mechanisms involved in thyroid organogenesis and differentiation have provided clues to identifying the genes that are involved in human congenital thyroid disorders and thyroid cancer. Mutations in the genes that encode the TTFs, as well as polymorphisms and epigenetic modifications, have been associated with thyroid pathologies. Here, we summarize the roles of the TTFs in thyroid development and the mechanisms by which they regulate expression of the genes involved in thyroid differentiation. We also address the implications of mutations in TTFs in thyroid diseases and in diseases not related to the thyroid gland.

Diagnosis of Metastatic Renal Cell Carcinoma on Fine-Needle Aspiration Cytology

Fine-needle aspiration has assumed an increasingly important role in the diagnosis and management of patients with advanced stage cancer. Given its predilection for metastases to distant sites and organs at the time of presentation, metastatic renal cell carcinoma (RCC) is not infrequently encountered in the setting of fine-needle aspiration for initial diagnosis. In some instances, fine-needle aspiration may be the only opportunity to obtain diagnostic tissue to diagnose and subclassify RCC. Therefore, cytopathologists and cytotechnologists should be familiar with and recognize the cytomorphology of RCC and the ancillary studies that can be used to confirm and subclassify RCC. Herein, we describe a case of metastatic RCC initially diagnosed on fine-needle aspiration, discuss the cytomorphologic features of RCC subtypes, and review pertinent ancillary immunohistochemical and cytogenetic adjuncts.

Diagnostic utility of PAX8 in differentiation of mullerian from non-mullerian tumors

Background:

Considering the high prevalence of female genital tract neoplasms, non-specific nature of the initial symptoms, higher possibility of metastasis by the time of diagnosis, importance of differentiating metastatic Mullerian tumors or metastatic breast cancer in the female genital tract, especially in the ovary, and lack of diagnostic markers with high sensitivity and specificity, the purpose of the current study was to evaluate the utility of Paired box protein8 (PAX8) expression in Mullerian and non-Mullerian neoplasms.

Materials and Methods:

In this descriptive–analytic, cross-sectional study, paraffin-embedded tissues of patients with definitive pathologic diagnosis of Mullerian and non-Mullerian tumors were selected. PAX8 immunohistochemical (IHC) staining was performed for all selected blocks. Immunopositivity of the slides for PAX8 was reviewed. It was defined as the presence of nuclear staining in at least 10% of the tumor cell nuclei.

Results:

Thirty-seven Mullerian (including 18 ovarian epithelial tumors, 17 endometrial carcinoma and two endocervical adenocarcinoma) and 37 non-Mullerian tumors were studied for PAX8 expression. Twenty-nine of 37 (78.4%) and one of 37 (2.7%) of the Mullerian and non-Mullerian tumors were positive for PAX8, respectively. The sensitivity and specificity of PAX8 by IHC for differentiation of Mullerian from non-Mullerian tumors was 78.4% and 97.3%, respectively.

Conclusion:

Our findings indicated that PAX8 could be used as a useful IHC marker for diagnosing Mullerian tumors. It has moderate to high sensitivity, but high specificity, for diagnosing carcinomas of Mullerian origin.

PAX2 and PAX8: useful markers for metastatic effusions

OBJECTIVE

It was the aim of this study to determine the utility of PAX2 and PAX8 in cytology effusions with metastatic tumor.

STUDY DESIGN

PAX2 and PAX8 immunohistochemical staining was performed on cell blocks of 89 pleural, pericardial and peritoneal effusions with benign diagnoses (18 cases), or secondary to renal cell carcinoma (RCC; 9 cases), müllerian carcinoma (21 cases) or non-müllerian carcinoma (41 cases).

RESULTS

PAX2 stained 0% (0/18) of controls, 100% (8/8) of RCCs, 35% (7/20) of müllerian carcinomas, and 2% (1/41) of non-müllerian carcinomas. PAX8 stained 6% (1/18) of control cases, 100% (9/9) of RCC cases, 100% (20/20) of müllerian carcinomas, and 5% (2/41) of non-müllerian carcinomas. PAX2 was 35% sensitive and 95% specific for müllerian carcinoma and 100% sensitive and 95% specific for RCC. PAX8 was 100% sensitive and 95% specific for müllerian carcinoma and 100% sensitive and 95% specific for RCC.

CONCLUSIONS

PAX8 is more sensitive than PAX2 for metastatic effusions from müllerian carcinomas (100 vs. 35%), while also having a higher intensity of staining than PAX2. However, PAX2 and PAX8 are both highly sensitive and specific for RCCs. PAX2 and PAX8 are valuable diagnostic markers for metastatic müllerian carcinomas and RCCs in effusion cytology. PAX8 is superior for carcinomas of müllerian origin.

Hepatocyte nuclear factor-1β is not a specific marker of clear cell carcinoma in serous effusions

BACKGROUND

The transcription factor hepatocyte nuclear factor-1β (HNF1β) has been reported to be a specific clear cell carcinoma marker, but its role in the diagnosis of serous effusions is largely unexplored. The objective of this study was to assess the diagnostic role of 2 commercial antibodies against HNF1β in effusion specimens.

METHODS

Effusions (n = 101), consisting of 43 ovarian adenocarcinomas (26 serous, 14 clear cell, 3 endometrioid), 37 nonovarian adenocarcinomas, 10 malignant mesotheliomas, 2 nonepithelial cancers, and 9 reactive specimens, were immunostained using antibodies from Santa Cruz Biotechnology Inc (Santa Cruz, Calif) and Atlas Antibodies AB (Stockholm, Sweden).

RESULTS

Use of the Santa Cruz antibody was associated with cytoplasmic or background staining in some specimens, whereas distinct staining with minimal background was observed using the Atlas antibody. The Santa Cruz antibody performed better in differentiating clear cell carcinoma from serous ovarian carcinoma and breast carcinoma, whereas staining was consistently negative in benign and malignant mesotheliomas using both antibodies. Distinct nuclear expression of HNF1β was observed in lung and gastrointestinal carcinomas, most often using the Atlas antibody.

CONCLUSIONS

The HNF1β antibody from Atlas performed better than its counterpart from Santa Cruz in terms of staining quality, but was less specific for clear cell carcinoma. Although HNF1β may be of diagnostic value in differentiating clear cell from serous carcinoma in cases with proven genital origin, the role of this marker is questionable in the differential diagnosis between the former tumors and adenocarcinomas of other origin, particularly in the setting of metastasis from an unknown primary tumor.

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.

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

PAX2 is a member of the PAX family of transcription factors that, together with PAX8, is involved in the regulation of the organogenesis of the kidney and the Müllerian system. Recent investigations have demonstrated that, among tumors, PAX2 is commonly expressed in epithelial tumors of the kidney and female genital tract. Although PAX2 expression has also been reported in B-cell lymphomas and rhabdomyosarcomas, especially alveolar rhabdomyosarcomas, it has been suggested that the positivity in these tumors was most probably due to a cross-reactivity of the anti-PAX2 antibody used in those investigations with other members of the PAX protein family. An analysis of published studies indicates that PAX2 sensitivity for epithelial renal neoplasms and epithelial tumors of the female genital tract is lower than that of PAX8. In contrast to the latter marker, however, PAX2 does not appear to be expressed in epithelial tumors of the thyroid gland or thymus. Because of its restricted expression, PAX2 has proved to be a useful immunohistochemical marker with a wide range of diagnostic applications in surgical pathology, some of which will be briefly reviewed.

Metastases to and from the Breast

Breast cancer is a common source of systemic metastatic disease. Distinguishing metastatic breast cancer from other types of malignancies can be diagnostically challenging but is important for correct treatment and prognosis. Nonmammary tumors can also metastasize to the breast, although this is a rare phenomenon. Differentiating a metastasis to the breast from a primary breast cancer can likewise be difficult. Knowledge of the clinical history and careful morphologic evaluation are the cornerstones of diagnosis. A panel of immunohistochemical stains tailored to the differential diagnosis at hand can provide helpful information in ambiguous cases.

Value of PAX8 and WT1 Immunostaining in Confirming the Ovarian Origin of Metastatic Carcinoma in Serous Effusion Specimens

We evaluated the detection rates of PAX8 and WT1 immunostaining in 68 (45 as cell blocks, 23 as smears) serous effusion specimens that had a cytologic diagnosis of metastatic carcinoma of ovarian origin. Of the cases, 58 (85%) were positive for PAX8, 56 (82%) were positive for WT1, and 64 (94%) were immunoreactive with either or both markers. Detection rates of PAX8 and WT1 were 85% (44/52) and 92% (48/52), respectively, for metastatic serous carcinoma and 100% (5/5) and 20% (1/5), respectively, for metastatic clear cell carcinoma. Detection rates using cell blocks and smears were 91% and 78%, respectively, with PAX8 and 82% and 83%, respectively, with WT1. We concluded that PAX8 and WT1 had comparable overall detection rates in confirming ovarian origin of malignant effusion. The combination of both markers substantially improved the detection rate. Cell blocks and smears can be used for staining, but a cell block is preferred for PAX8 staining.

Thyroid-specific transcription factors and their roles in thyroid cancer

Homeodomain, forkhead domain, and paired domain-containing transcription factors play a major role in development, tissue-specific gene expression, and tissue homeostasis in organs where they are expressed. Recently, their roles in stem cell and cancer biology are emerging. In the thyroid, NKX2-1, FOXE1, and PAX8 transcription factors are responsible for thyroid organogenesis and expression of thyroid-specific genes critical for thyroid hormone synthesis. In contrast to their known roles in gene regulation, thyroid development and homeostasis, their involvement in stem cell, and/or cancer biology are still elusive. In order to further understand the nature of thyroid cancer, it is critical to determine their roles in thyroid cancer.