The Binding of Thyroid Transcription Factor-1 and Hepatocyte Paraffin 1 to Mitochondrial Proteins in Hepatocytes

Frequency of antithyroid antibodies in patients with primary biliary cholangitis

OBJECTIVE

Primary biliary cholangitis (PBC) is an autoimmune disease of liver that may be associated with other conditions, including autoimmune thyroid diseases. We aimed to investigate the frequency of anti-thyroperoxidase antibodies (TPO-Ab), antithyroglobulin antibodies (TG-Ab), and anti-thyrotropin receptor antibodies (TSHR-Ab) in Tunisian patients with PBC.

METHODS

Sera of 80 patients with PBC were collected over a 9-year period. A total of 189 healthy blood donors (HBD) were included in the control group. Measurements of TPO-Ab and TG-Ab were performed using indirect enzyme-linked immunosorbent assay (ELISA). Competitive ELISA was used to assess TSHR-Ab.

RESULTS

Antithyroid antibodies (ATA) were significantly more frequent in PBC patients than in the control group (13.7% vs 1.6%; P < 10-3). Out of 11 patients with ATA, 10 (90.9%) were female. Nine patients and 2 HBD had TPO-Ab (11.2% vs 1%; P < 10-3). TG-Ab were more frequent in patients than in healthy subjects but the difference was not statistically significant (6.2% vs 1.6%; P = .1). TPO-Ab and TG-Ab were present together in 3 patients (3.7%). TSHR-Ab were absent in patients and controls.

CONCLUSION

This study shows that PBC is associated with a high frequency of ATA but not TG-Ab or TSHR-Ab.

Patterns of Immunoreactivity with TTF-1 Antibodies 8G7G3/1 and SPT24 Suggest Distinct Immunoprofiles Between Most Pulmonary and Nonpulmonary Small Cell Carcinomas

Introduction. Small cell carcinoma can arise from various sites. Herein, we analyze the ability of 2 thyroid transcription factor-1 (TTF-1) antibodies (SPT24 and 8G7G3/1) to separate pulmonary from nonpulmonary small cell carcinoma. Materials and Methods. We analyzed 26 pulmonary and 83 nonpulmonary small cell carcinomas, and 14 Merkel cell carcinomas. Each tumor was stained with SPT24 and 8G7G3/1. Extent of nuclear staining was scored as diffuse (>50%), focal (11%-50%), rare (1%-10%), or negative (<1%). Results. All pulmonary small cell carcinomas were positive for SPT24 and 8G7G3/1. Four Merkel cell carcinomas (29%) were positive for SPT24 (ranging from rare-to-diffuse), while 2 (14%) showed rare expression with 8G7G3/1. For nonpulmonary small cell carcinomas, 69 (83%) were positive for SPT24 and 40 (48%) were positive for 8G7G3/1. For SPT24 positive tumors, the extent of 8G7G3/1 expression was equal in 17 (25%) and less in 52 tumors (75%), including 29 (42%) that were negative for 8G7G3/1. No nonpulmonary small cell carcinoma had more staining with 8G7G3/1 compared to SPT24. The differences in staining between 8G7G3/1 and SPT24 in the nonpulmonary cohort were statistically significant (P < 0.0001) with no significant difference between primary and metastatic lesions for 8G7G3/1 (P  =  0.66) or SPT24 (P  =  0.77). Conclusion. Most pulmonary small cell carcinomas are diffusely positive for both SPT24 and 8G7G3/1, whereas most nonpulmonary small cell carcinomas exhibit focal-to-no staining with 8G7G3/1 and significantly less staining with 8G7G3/1 compared to SPT24. However, these trends are not absolute and should be interpreted in conjunction with clinical and radiological findings.

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.

Diagnostic Utility of Thyroid Transcription Factor-1 in Ovarian Carcinoma and Its Relationship With Clinicopathologic Prognostic Parameters

Although thyroid transcription factor-1 (TTF-1) is considered a relatively sensitive and specific marker for lung and thyroid neoplasms, it can occasionally be expressed in other tumors. Few immunohistochemical studies have been conducted on TTF-1 expression in ovarian carcinomas with discrepant results. To date, only 1 study compared different TTF-1 clones in ovarian carcinoma. This study is designed to evaluate the expression of TTF-1 clones in ovarian carcinomas and investigate TTF-1 association with clinicopathologic prognostic parameters. A retrospective immunohistochemical study was conducted on 62 primary ovarian carcinomas and 15 normal ovarian tissues using 2 clones of TTF-1 antibody (SPT24 and 8G7G3/1). Nuclear expression of SPT24 and 8G7G3/1 clones of TTF-1 was detected in 17.7% and 3.2% of ovarian carcinomas, respectively. Positive cytoplasmic immunostaining of clone SPT24 was detected in 1.6% of cases. In contrast, normal ovarian tissue showed negative expression of both clones. A highly significant difference was observed between both clones regarding their sensitivity in ovarian carcinomas (P=0.004). A significant inverse relationship was observed between TTF-1 (SPT24 clone) expression and tumor stage (P=0.022). TTF-1 expression is not exclusive to lung and thyroid tissue. It is expressed in ovarian carcinomas where clone SPT24 is more sensitive than clone 8G7G3/1. TTF-1 might be of diagnostic utility in evaluating neoplasms of unknown primary origin as well as adenocarcinomas involving the lung in patients with a history of a gynecologic malignancy. Moreover, TTF-1 expression might be a good prognostic factor in ovarian carcinoma.

Distinct pathways of pathogenesis of intraductal oncocytic papillary neoplasms and intraductal papillary mucinous neoplasms of the pancreas

Intraductal oncocytic papillary neoplasm (IOPN) of the pancreas is classified as a variant of intraductal papillary mucinous neoplasm (IPMN) in the WHO guidelines. However, the neoplastic cells of IOPNs are unique, with distinctive architecture/oncocytic cytoplasm. Although molecular/immunohistochemical features of other IPMN variants have been extensively studied, those of IOPNs have not been well characterized. Expression profile of antibodies associated with genetic alterations previously described for ductal adenocarcinomas (DAs) and IPMNs (SMAD4/β-catenin/p53/mesothelin/claudin-4) as well as antibodies to mucins and differentiation markers [MUC1/MUC2/MUC5AC/MUC6/CDX2/hepatocyte paraffin-1 (HepPar-1)] was investigated in 24 IOPNs and 22 IPMNs to assess the similarities/differences between these tumors. Expression of mesothelin and claudin-4 was dissimilar between these tumor types: A higher proportion of IOPNs labeled with mesothelin [21/24 (87.5 %) of IOPNs, 6/22 (27 %) of IPMNs, p < 0.001], while the reverse was true for claudin-4 [2/23 (9 %) of IOPNs, 9/22 (41 %) of IPMNs, p = 0.01]. The results of immunolabeling for SMAD4/β-catenin/p53 were similar in both: None of the cases showed SMAD4 loss in the intraductal components, and only 1/21 (5 %) of IOPNs and 2/22 (9 %) of IPMNs revealed abnormal β-catenin expression (p = 0.49). Nuclear p53 accumulation was seen mostly in architecturally complex/high-grade dysplasia areas in both. Immunolabeling for MUC proteins showed that almost all lesions expressed MUC5AC. Twelve of the 24 (50 %) IOPNs and 6/22 (27 %) of IPMNs (p = 0.11) labeled for MUC1, whereas 7/24 (29 %) of IOPNs and 10/22 (45 %) of IPMNs labeled for MUC2 (p = 0.25). MUC6 was expressed in 8/9 (89 %) of IOPNs (strong) and 6/21 (29 %) of IPMNs (weak) (p = 0.002). Fourteen of the 23 (61 %) IOPNs and 4/22 (18 %) of IPMNs labeled for HepPar-1 (p = 0.003). These results show that IOPNs have distinct immunoprofile and provide support for the proposition that IOPN is a distinct entity developing through a mechanism different from other pancreatic ductal neoplasms.

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.

When tissue antigens and antibodies get along: revisiting the technical aspects of immunohistochemistry--the red, brown, and blue technique

Once focused mainly on the characterization of neoplasms, immunohistochemistry (IHC) today is used in the investigation of a broad range of disease processes with applications in diagnosis, prognostication, therapeutic decisions to tailor treatment to an individual patient, and investigations into the pathogenesis of disease. This review addresses the technical aspects of immunohistochemistry (and, to a lesser extent, immunocytochemistry) with attention to the antigen-antibody reaction, optimal fixation techniques, tissue processing considerations, antigen retrieval methods, detection systems, selection and use of an autostainer, standardization and validation of IHC tests, preparation of proper tissue and reagent controls, tissue microarrays and other high-throughput systems, quality assurance/quality control measures, interpretation of the IHC reaction, and reporting of results. It is now more important than ever, with these sophisticated applications, to standardize the entire IHC process from tissue collection through interpretation and reporting to minimize variability among laboratories and to facilitate quantification and interlaboratory comparison of IHC results.

Cytoplasmic staining of TTF-1 in the differential diagnosis of hepatocellular carcinoma

Thyroid transcription factor 1 (TTF-1) is a widely used biomarker in surgical pathology. Its nuclear staining is sensitive and specific for the diagnosis of primary pulmonary and thyroid adenocarcinoma as well as small cell carcinomas arising in many organs. The cytoplasmic staining of TTF-1 is also observed, particularly in the benign and malignant hepatic cells. It has been controversial whether TTF-1 cytoplasmic staining is reliable enough to have diagnostic value. This review focuses on this issue and explores the potential application of TTF-1 cytoplasmic staining in the differential diagnosis of hepatocellular carcinoma from other primary and metastatic malignancies in the liver. The mechanism of TTF-1 cytoplasmic staining is also discussed.

Thyroid transcription factor 1 expression in sellar tumors: a histogenetic marker?

Pituicytomas are rare low-grade gliomas of the neurohypophysis. Their morphology and variable immunophenotype have led to speculation that they arise from pituicytes. Given the role of thyroid transcription factor 1 (TTF-1) in the developing rodent infundibulum and its expression in the adult rat neurohypophysis, we speculated that TTF-1 would be a marker of human pituicytes. Using immunohistochemistry, we found that TTF-1 is strongly expressed in fetal and adult human pituicytes. A survey of sellar masses demonstrated specific TTF-1 expression in pituicytomas (n = 3), atypical pituicytomas (n = 2), and granular cell tumors (n = 4), indicating a common pituicyte lineage. TTF-1 expression in spindle cell oncocytomas (n = 8) is less easily explained but invites speculation. Our observations may have implications for the classification of these rare sellar neoplasms, all the while acknowledging the morphological diversity of pituicyte-related neoplasms.

Thyroid transcription factor-1 expression in ovarian epithelial neoplasms

Thyroid transcription factor-1 (TTF-1) protein expression is widely used in the diagnosis of lung and thyroid carcinomas. Although there have been reports of TTF-1 immunoreactivity in tumors other than those originating in the lung or the thyroid, the expression of this marker has been studied in only a limited number of ovarian neoplasms. Our study examines the incidence of TTF-1 expression in a variety of ovarian epithelial neoplasms. Tissue microarrays of 138 ovarian serous carcinomas, 65 endometrioid adenocarcinomas, 35 mucinous adenocarcinomas, 30 mucinous neoplasms of low malignant potential, and 10 clear cell carcinomas were stained with anti-TTF1-antibody. In addition, whole tissue sections of 19 serous carcinomas, 5 endometrioid adenocarcinomas, 7 mucinous adenocarcinomas, and 3 clear cell carcinomas were stained. In the tissue microarrays, TTF-1 nuclear expression was demonstrated in 2 of 65 (3%) of the endometrioid adenocarcinomas; no nuclear immunoreactivity was identified in the remaining ovarian neoplasms. In the whole tissue sections, TTF-1 nuclear staining was present in 7 of 19 (37%) serous carcinomas, 1 of 5 (20%) endometrioid adenocarcinomas, and 1 of 3 (33%) clear cell carcinomas. In most of the positive cases, staining was focal, but in one endometrioid adenocarcinoma in the tissue microarray and in one serous and one clear cell carcinoma in the whole tissue sections, there was diffuse positivity. Overall, there was nuclear staining in 0.7% of tumors in the tissue microarray and 26% in the whole tissue sections. Although TTF-1 nuclear expression is generally considered to be a relatively specific marker for lung and thyroid neoplasms, the occasional immunoreactivity of ovarian carcinomas should be considered in the evaluation of neoplasms of unknown primary origin. It should also be taken into consideration when evaluating adenocarcinomas involving the lung in patients with a history of a gynecologic malignancy.

Recommendations for improved standardization of immunohistochemistry

Immunohistochemistry (IHC) continues to suffer from variable consistency, poor reproducibility, quality assurance disparities, and the lack of standardization resulting in poor concordance, validation, and verification. This document lists the recommendations made by the Ad-Hoc Committee on Immunohistochemistry Standardization to address these deficiencies. Contributing factors were established to be underfixation and irregular fixation, use of nonformalin fixatives and ancillary fixation procedures divested from a deep and full understanding of the IHC assay parameters, minimal or absent IHC assay optimization and validation procedures, and lack of a standard system of interpretation and reporting. Definitions and detailed guidelines pertaining to these areas are provided.