The contribution of immunohistochemical staining in tumour diagnosis

Composite Biomarker Image for Advanced Visualization in Histopathology

Immunohistochemistry (IHC) biomarkers are essential tools for reliable cancer diagnosis and subtyping. It requires cross-staining comparison among Whole Slide Images (WSIs) of IHCs and hematoxylin and eosin (H&E) slides. Currently, pathologists examine the visually co-localized areas across IHC and H&E glass slides for a final diagnosis, which is a tedious and challenging task. Moreover, visually inspecting different IHC slides back and forth to analyze local co-expressions is inherently subjective and prone to error, even when carried out by experienced pathologists. Relying on digital pathology, we propose "Composite Biomarker Image" (CBI) in this work. CBI is a single image that can be composed using different filtered IHC biomarker images for better visualization. We present a CBI image produced in two steps by the proposed solution for better visualization and hence more efficient clinical workflow. In the first step, IHC biomarker images are aligned with the H&E images using one coordinate system and orientation. In the second step, the positive or negative IHC regions from each biomarker image (based on the pathologists' recommendation) are filtered and combined into one image using a fuzzy inference system. For evaluation, the resulting CBI images, from the proposed system, were evaluated qualitatively by the expert pathologists. The CBI concept helps the pathologists to identify the suspected target tissues more easily, which could be further assessed by examining the actual WSIs at the same suspected regions.

Quantification of structural heterogeneity in H&E stained clear cell renal cell carcinoma using refractive index tomography

Clear cell renal cell carcinoma (ccRCC) is a common histopathological subtype of renal cancer and is notorious for its poor prognosis. Its accurate diagnosis by histopathology, which relies on manual microscopic inspection of stained slides, is challenging. Here, we present a correlative approach to utilize stained images and refractive index (RI) tomography and demonstrate quantitative assessments of the structural heterogeneities of ccRCC slides obtained from human patients. Machine-learning-assisted segmentation of nuclei and cytoplasm enabled the quantification at the subcellular level. Compared to benign regions, malignant regions exhibited a considerable increase in structural heterogeneities. The results demonstrate that RI tomography provides quantitative information in synergy with stained images on the structural heterogeneities in ccRCC.

Predicting Prognosis and Platinum Resistance in Ovarian Cancer: Role of Immunohistochemistry Biomarkers

Ovarian cancer is a lethal reproductive tumour affecting women worldwide. The advancement in presentation and occurrence of chemoresistance are the key factors for poor survival among ovarian cancer women. Surgical debulking was the mainstay of systemic treatment for ovarian cancer, which was followed by a successful start to platinum-based chemotherapy. However, most women develop platinum resistance and relapse within six months of receiving first-line treatment. Thus, there is a great need to identify biomarkers to predict platinum resistance before enrolment into chemotherapy, which would facilitate individualized targeted therapy for these subgroups of patients to ensure better survival and an improved quality of life and overall outcome. Harnessing the immune response through immunotherapy approaches has changed the treatment way for patients with cancer. The immune outline has emerged as a beneficial tool for recognizing predictive and prognostic biomarkers clinically. Studying the tumour microenvironment (TME) of ovarian cancer tissue may provide awareness of actionable targets for enhancing chemotherapy outcomes and quality of life. This review analyses the relevance of immunohistochemistry biomarkers as prognostic biomarkers in predicting chemotherapy resistance and improving the quality of life in ovarian cancer.

Enabling automated and reproducible spatially resolved transcriptomics at scale

Spatial information of tissues is an essential component to reach a holistic overview of gene expression mechanisms. The sequencing-based Spatial transcriptomics approach allows to spatially barcode the whole transcriptome of tissue sections using microarray glass slides. However, manual preparation of high-quality tissue sequencing libraries is time-consuming and subjected to technical variability. Here, we present an automated adaptation of the 10x Genomics Visium library construction on the widely used Agilent Bravo Liquid Handling Platform. Compared to the manual Visium library preparation, our automated approach reduces hands-on time by over 80% and provides higher throughput and robustness. Our automated Visium library preparation protocol provides a new strategy to standardize spatially resolved transcriptomics analysis of tissues at scale.

Immunohistochemistry in Historical Perspective: Knowing the Past to Understand the Present

Immunohistochemistry is an extraordinary and extensively used technique whereby antibodies are used to detect antigens in cells within a tissue section. It has numerous applications in medicine, particularly in cancer diagnosis. It was Albert Hewett Coons, Hugh J Creech, Norman Jones, and Ernst Berliner who conceptualized and first implemented the procedure of immunofluorescence in 1941. They used fluorescein isothiocyanate (FITC)-labelled antibodies to localize pneumococcal antigens in infected tissues. Since then, with improvement and development of protein conjugation, enzyme labels have been introduced, such as peroxidase and alkaline phosphatase. The history of immunohistochemistry (IHC) combines physiology, immunology, biochemistry, and the work of various Nobel Prize laureates. From von Behring who was awarded de first Nobel Prize in 1901 for his work on serum therapy to the 1984 Nobel Prize for the discovery of monoclonal antibodies by Milstein, Kohler, and Jerne, IHC is a story of cooperation and collaboration which led to the development of this magnificent technique that is used daily in anatomical pathology laboratories worldwide.

The Role of Immunohistochemistry for Primary Oral Diagnosis in a Brazilian Oral Pathology Service

A proper antibody panel selection is one of the most important factors to reach an adequate diagnosis in challenging cases. This retrospective study was designed to determine the contribution of immunohistochemistry (IHC) in the primary diagnosis of oral diseases in one of the main services of oral pathology in the State of São Paulo, Brazil, and to identify the most common antibodies used, and recommend diagnostic algorithms based on our experience with challenging lesions. A total of 1698 IHC stains were performed in 401 cases from a total of 28,804 cases received from public dental clinics and private dental practitioners within a period of 13 years, representing a frequency of 1.4% of IHC solicitations. Among these, 112 (28%) were mandatory to reach a final diagnosis and 255 (63.6%) were confirmative. In 34 (8.4%) cases, it was not possible to reach a conclusive/final diagnosis, even with IHC. Regarding the nature of the lesions, 210 (52.3%) were benign, 163 (40.6%) were malignant tumors, 13 (3.2%) were reactive, 10 (2.5%) were premalignant, and 5 (1.2%) were lesions of uncertain malignancy. Small amount of tissue of some incisional biopsies, overlapping features of spindle cell lesions (epithelial, neural, melanocytic, smooth muscle, endothelial, and fibroblastic/myofibroblastic cell differentiation), and overlapping features of salivary gland lesions were the most frequent challenges in which IHC stains were requested. Spindle cell lesions were the most frequent (22%) among all cases that required IHC to reach a final diagnosis. The implementation of IHC for routine practice requires a wide range of markers, proper antibody selection, and knowledge to interpret the subjectivity of staining. The inherent limitation of incisional biopsies was pointed as a reason to inconclusive diagnosis, despite a wide range of antibodies that our laboratory displays.

Automated Immunohistochemistry Assay for the Detection of Napsin-A in Formalin-Fixed Paraffin-Embedded Tissues from Lung Tumors

Immunohistochemistry (IHC) enables the selective detection of proteins in cells of formalin-fixed-paraffin-embedded (FFPE) tissue sections. This technique plays a key role in the identification and classification of primary lung cancer tumors through the evaluation of the expression of the aspartic proteinase Napsin-A. However, immunohistochemistry is a complex process involving many critical steps and the lack of standardization as well as inappropriate analytical conditions may contribute to inconsistent results between laboratories. Automated immunohistochemistry addresses this issue by ensuring the quality and the reproducibility of the results among different laboratories. Here we describe an automated IHC protocol used in our laboratory for the detection of Napsin-A in FFPE lung tissue sections.

Anti-diabetic effect of a novel oligosaccharide isolated from Rosa canina via modulation of DNA methylation in Streptozotocin-diabetic rats

BACKGROUND

Diabetes mellitus (DM) is a well-known clinical entity with various late complications. There is a surge of research aiming to use the medical herb in the management of DM.

OBJECTIVE

This study aimed to investigate whether the alleviation of DM by an isolated compound from Rosa canina is mediated by DNA methylation in STZ-diabetic rats.

METHODS

Sixty adult Wistar male rats were classified into control, diabetic and treatment groups. Rats were treated with STZ (40 mg/kg), metformin (500 mg/kg), and oligosaccharide fraction (OF; 10, 20 and 30 mg/kg) isolated from Rosa canina. DNA was extracted from the blood and pancreas to determine DNA methylation using the Global DNA Methylation kit. The expressions of DNA methyltransferases (Dnmts), PDX1, Ins1, GCK and PTP1B2 were determined by using qRT-PCR.

RESULTS

The significant blood glucose-lowering potential of OF was associated with a reduced level of global DNA methylation (p < 0.05). The expression levels of Dnmts 1 and 3α increased in the pancreas and blood from diabetic rats compared to control group which declined by OF treatment (p < 0.05). Paradoxically, the expression of Dnmt 3β augmented in the pancreas and blood of OF group compared to diabetic ones (p < 0.05). Besides, the expressions of Pdx1, PTP1B2, Ins1 and GCK increased in OF-treated rats compared to diabetic groups.

CONCLUSION

Results revealed that DNA methylation plays a causal role in the effectiveness of the isolated OF. Furthermore, the possible regenerative potential of oligosaccharide in diabetic rats may have contributed to the modulation of DNA methylation.

Immunohistochemistry utilization in the diagnosis of melanoma

BACKGROUND

The use of immunohistochemical (IHC) stains in dermatopathology is commonplace; however, little is known regarding utilization trends in melanoma diagnosis. Current Medicare local coverage determinations (LCDs) state that most pigmented lesions, including melanoma, can be diagnosed using H&E alone.

METHODS

Histopathology reports for all biopsy-proven melanomas excised between January 1, 2017 and June 30, 2018, at a single dermatology clinic, were identified with the following parameters abstracted: laboratory/dermatopathologist rendering the diagnosis, whether IHC was performed, type/number of stains utilized, presence/depth of invasion, and melanoma subtype. The association of characteristics with IHC utilization was evaluated using χ² test for categorical variables.

RESULTS

Three hundred and fifty six eligible melanomas were identified. IHC was employed in 228 (64%) of the diagnoses. Invasive melanoma was diagnosed in 199 cases (55.9%) while 157 (44.1%) were identified as melanoma in situ (MIS). Of the 228 that utilized IHC, 117 were performed on invasive melanoma (58.8%) and 111 were performed on MIS (70.7%).

CONCLUSION

Our findings suggest a higher IHC usage for the diagnosis of melanoma than previously reported. Existing LCDs regarding IHC utilization in melanoma do not reflect the current state of practice. Further investigation regarding IHC utilization and the development of appropriate-use criteria for melanoma IHC is necessary.

Advances in Diagnostic Procedures and Their Applications in the Era of Cancer Immunotherapy

Diagnostic procedures play critical roles in cancer immunotherapy. In this chapter, we briefly discuss three major diagnostic procedures widely used in immunotherapy: immunohistochemistry, next-generation sequencing, and flow cytometry. We also describe the uses of other diagnostic procedures and preclinical animal models in cancer immunotherapy translational research.

Challenges and future of biomarker tests in the era of precision oncology: Can we rely on immunohistochemistry (IHC) or fluorescence in situ hybridization (FISH) to select the optimal patients for matched therapy?

Molecular techniques have improved our understanding of the pathogenesis of cancer development. These techniques have also fueled the rational development of targeted drugs for patient populations stratified by their genetic characteristics. These novel methods have changed the classic paradigm of diagnostic pathology; among them are IHC, FISH, polymerase chain reaction (PCR) and microarray technology. IHC and FISH detection methods for human epidermal growth factor receptor-2 (HER2), epidermal growth factor receptor (EGFR) and programmed death ligand-1 (PD-L1) were recently approved by the Food and Drug Administration (FDA) as routine clinical practice for cancer patients. Here, we discuss general challenges related to the predictive power of these molecular biomarkers for targeted therapy in cancer medicine. We will also discuss the prospects of utilizing new biomarkers for fibroblast growth factor receptor (FGFR) and hepatocyte growth factor receptor (cMET/MET) targeted therapies for developing new and robust predictive biomarkers in oncology.

A study on role of triiodothyronine (T3) hormone on the improvement of articular cartilage surface architecture

The present study was aimed to investigate the effect of triiodothyronine (T3) on the improvement of articular cartilage surface architecture at in vitro level. The T3 hormone was applied to neo-tissues in the range of 50, 100, 150 and 200ng/ml for 5 weeks. At the end of the treatment, biochemical and histological evaluation was carried out in the neo-tissues. T3 hormone application significantly increased the collagen production in neo-cartilage tissues. The properties of tensile and compressive were significantly increased compared to the controls. However, T3 hormone application also induced hypertrophy. At the higher dose concentration of T3 hormone application, tensile and compressive properties were tremendously increased 4.3 and 4.6 fold respectively. Taking all these data together, it suggested that the T3 hormone application could be a potential agent to increase the functional properties such tensile and compressive in neo-tissues.

Analysis of CCN Expression by Immunofluorescence on Skin Cells, Skin, and Reconstructed Epidermis

During a long time, immunofluorescence has been neglected to benefit of molecular biology especially genetics, transcriptomics, and proteomics analyses. These techniques give good results on cell culture but for organs that are made of numerous cells with several compartments, various states of differentiation as in epidermis, immunohistochemistry is always relevant. Double (triple) staining by immunofluorescence allows positive cells identification in complex cell structure (for example, pericytes and endothelial cells in vessels) and subcellular localizations. In order to, due to improvement of antibodies avoiding especially species cross-reactions, microscopy and specific softwares, quality of staining, and acquired images have been upgraded. Consequently, this technique permits, as molecular biology analyses, quantification of the level of expression as intensity of fluorescence can be measured in each cells and each compartments (nuclear, cytoplasmic). In order to immunofluorescence on cells and tissue needs few materials and gives at the same times qualitative and quantitative results and must be used more widely especially when a mutation was associated to a disease.

Immunostain use in the diagnosis of melanomas referred to a tertiary medical center: a 15-year retrospective review (2001-2015)

BACKGROUND

Little is known regarding the clinical practice of immunohistochemistry in the diagnosis of melanoma. We aimed to assess the incidence of immunostain usage by referring pathologists and dermatopathologists in melanoma cases sent for consultative review. As a secondary objective, associations between immunostain use and specific melanoma characteristics were also evaluated.

METHODS

This is a retrospective review of consultation reports of referred melanomas at a tertiary academic center in New York, NY from 2001 to 2015. Univariate regression analysis was performed on melanomas with accompanying immunostains and on characteristics such as Breslow's depth, location, prognostic factors and morphologic subtypes. Associations between immunostain usage and these characteristics were analyzed using Fisher's exact test.

RESULTS

Immunostain use significantly increased over the study period (p < 0.001) and was more likely to be associated with melanomas that were thicker [odds ratio (OR) = 2.5; 1.7-3.6]; located on the head and neck (OR = 1.6; 1.4-1.9) or acral sites (OR = 1.5; 1.1-2.0); had ulceration (OR = 2.1; 1.6-2.8), dermal mitoses (OR = 1.3; 1.1-1.5), or perineural invasion (OR = 3.6; 2.0-6.5); or were of desmoplastic (OR = 7.4; 4.5-12), amelanotic (OR = 7.1; 3.6-14), or nevoid subtypes (OR = 4.0; 1.7-8.9).

CONCLUSIONS

Immunostain use in the diagnosis of melanoma has increased significantly in the past 15 years for reasons that remain unclear.

Interleukin-1 (IL-1) immunohistochemistry assay in oral squamous cell carcinoma

This chapter describes an immunohistochemistry method to analyze interleukin-1 (IL-1) in oral squamous cell carcinoma. The described protocol has been optimized for IL-1 detection in formalin-fixed paraffin-embedded oral tissue sections by light microscopy. A few common pitfalls and problems associated with immunohistochemical staining are discussed.

Applications of immunohistochemistry

Immunohistochemistry (IHC) is an important application of monoclonal as well as polyclonal antibodies to determine the tissue distribution of an antigen of interest in health and disease. IHC is widely used for diagnosis of cancers; specific tumor antigens are expressed de novo or up-regulated in certain cancers. This article deals with the various applications of IHC in diagnosis of diseases, with IHC playing an important role in diagnostic and research laboratories.

Standardization in immunohistology

The rapid acceptance of immunohistology as an invaluable adjunct to morphologic diagnosis has been possible because of the development of new and more sensitive antibodies and detection systems that allow its application to formalin-fixed, paraffin-embedded tissue (FFPT). More importantly, antigen-retrieval techniques have resulted in some degree of consistency allowing immunohistology to be used reliably as a diagnostic tool. The advent of prognostic and predictive biomarkers, and the desire for individualized therapy has resulted in mounting pressure to employ the immunohistological assay in a quantitative manner. While it was not a major issue when the technique was employed in a qualitative manner, the numerous variables in the preanalytical and analytical phases of the test procedure that influence the immunoexpression of proteins in FFPT become critical to standardization. Tissue fixation is pivotal to antigen preservation but exposure to fixative prior to accessioning by the laboratory is not controlled. Antigen retrieval, crucial in the analytical phase, continues to be employed in an empirical manner with the actual mechanism of action remaining elusive. There is great variation in reagents, methodology, and duration of tissue processing and immunostaining procedure, and the detection systems employed are not standardized between laboratories. While many of these variables are offset by the application of antigen retrieval, which enables the detection of a wide range of antigens in FFPT, the method itself is not standardized. This myriad of variables makes it inappropriate to provide meaningful comparisons of results obtained in different laboratories and even in the same laboratory, as in current practice, each specimen experiences different preanalytical variables. Furthermore, variables in interpretation exist and cutoff thresholds for positivity differ. Failure to recognize false-positive and false-negative stains leads to further errors of quantitative measurement. Many of the problems relating to the technology and interpretation of immunostaining originate from failure to recognize that this procedure is different from other histological stains and involves many more steps that cannot be monitored until the end result is attained. While several remedial measures can be suggested to address some of these problems, accurate and reproducible quantitative assessment of immunostains presently remains elusive as important variables that impact on antigen preservation in the paraffin-embedded biopsy -cannot be standardized.

Immunohistochemistry as an important tool in biomarkers detection and clinical practice

The immunohistochemistry technique is used in the search for cell or tissue antigens that range from amino acids and proteins to infectious agents and specific cellular populations. The technique comprises two phases: (1) slides preparation and stages involved for the reaction; (2) interpretation and quantification of the obtained expression. Immunohistochemistry is an important tool for scientific research and also a complementary technique for the elucidation of differential diagnoses which are not determinable by conventional analysis with hematoxylin and eosin. In the last couple of decades there has been an exponential increase in publications on immunohistochemistry and immunocytochemistry techniques. This review covers the immunohistochemistry technique; its history, applications, importance, limitations, difficulties, problems and some aspects related to results interpretation and quantification. Future developments on the immunohistochemistry technique and its expression quantification should not be disseminated in two languages—that of the pathologist and another of clinician or surgeon. The scientific, diagnostic and prognostic applications of this methodology must be explored in a bid to benefit of patient. In order to achieve this goal a collaboration and pooling of knowledge from both of these valuable medical areas is vital

Histogenesis of human renal cell carcinoma by using electron microscopy and immunohistochemical techniques

Electron microscopy and immunohistochemical techniques are powerful tools for the determination of tissue origin. Both techniques have been used in the current experiment for histogenesis of renal cell carcinoma. Fifty kidney tumors were subjected to immunohistochemical detection for intermediate filaments cytokeratin and vimentin, which are normally expressed in epithelial tissue and mesenchymal tissues, respectively. Twenty cases of the above were examined by electron microscopy for detection of ultrastructure features. From each kidney, two specimens were taken, one from the diseased area and another far from it to serve as a control. Immunohistochemical study revealed in cases of renal cell carcinoma, cytokeratin and vimentin were expressed alone in 44% of cases, and 40% of cases, respectively. Twelve percent of cases were coexpressed with both cytokeratin and vimentin. Electron microscopic study of diseased specimens revealed the expression of desmosomes which was observed in almost all tumor specimens. The expression of the vimentin in some cases either alone or with cytokeratin was interpreted as a change in the characters of some tumor cells which indicates the need for additional techniques in such cases to get the proper interpretation. The prevalence of the expression of cytokeratin and the persistence existence of desmosomes indicate the epithelial origin of the tumor. This data is very beneficial for determination of line of therapy and follow up of the patients. The results confirm the power of combined use of both immunohistochemistry and electron microscopy in the field of histogenesis.

Basal Lamina Visualization Using Color Image Processing and Pattern Recognition

In histologic assessment, the absence of basal lamina is a useful feature for distinguishing invasive malignancy from benign and in situ lesions. As this feature is not possible to assess in routine H&E sections, pathologists have instead relied on histochemical and immunohistochemical stains to show components of the basal lamina such as laminin or type IV collagen. Standard image-processing software with the necessary image-processing toolbox (Matlab v5, Mathworks, Natick, MA) was used in a unique combination of color image processing and pattern recognition techniques to accentuate the collagenous stroma surrounding glands, which approximates basal lamina, in a series of benign, in situ, and invasive breast proliferations. Distinct differences in pattern were found between benign and invasive lesions, and also between in situ and malignant lesions, corresponding to that observed with type IV collagen immunostaining. Compared with immunostaining, this computer-generated method had a sensitivity of 0.96, specificity of 0.89, positive predictive value of 0.92, negative predictive value of 0.89, positive likelihood ratio of 9.1, and negative likelihood ratio of 0.042. Digital image processing serves as a less expensive and faster way of visualizing basal lamina and represents a useful adjunct to identify invasive malignancy in routinely stained sections. In addition, digital visualization of basal lamina is readily amenable to quantitative assessment, and the method provides a basis for the development of computer-based cancer diagnosis.

Pitfalls in diagnostic immunohistology

The integration of immunostaining as an often-essential component of morphologic assessment makes it necessary that pathologists are familiar with the many technical and interpretive pitfalls that may arise because of the wide variety of factors that can significantly influence the ability to demonstrate relevant antigens in paraffin-embedded tissue sections. Pre-analytical variables that affect immunostaining include fixation, type of fixative, duration, temperature, and pH of fixation, variables in tissue processing, antigen loss resulting from delays in fixation, tissue necrosis, and levels of antigen expression. Analytical factors relate to the complex and sometimes capricious immunolabeling procedure that has as variables the specificity and sensitivity of the antibody clone, reagent dilution, detection system, and chromogen, and importantly, the method of antigen retrieval, which has its own set of variables such as time, temperature, method of heat generation, retrieval solution pH and molarity, and the synergistic action of proteolytic digestion. To obtain the highest diagnostic yield from immunostaining the correct questions must be asked and the pathologist must have familiarity with the characteristics of the antibody, its cross reactivity, if any, and localization of antigen in the cell to understand thresholds and cut-off levels and to recognize false-positive staining. Proper utilization of immunostaining requires that it is employed as a morphology-based technique and not interpreted in isolation.

The cost-effectiveness of immunohistochemistry

OBJECTIVE

To evaluate the cost-effectiveness of immunohistochemistry.

DESIGN

Using a theoretical decision analytic model, the cost-effectiveness of immunohistochemistry was evaluated in different scenarios depicting the beneficial use of immunohistochemistry. Data regarding the effectiveness of immunohistochemistry were obtained from the medical literature and costs were obtained from Allegheny General Hospital.

SETTINGS

The scenarios depicted both private practice and university patients from which anatomic pathology specimens were obtained. Immunohistochemistry was subsequently performed on these specimens.

MAIN OUTCOME MEASURES

Cost, life expectancy, diagnostic certainty, ability to predict prognosis, and cost-effectiveness were evaluated.

RESULTS

In all scenarios, immunohistochemistry was cost-effective at very low efficacies. Assuming a per-antibody cost of $50 and use of a 5-antibody panel, immunohistochemistry was cost-effective if it resulted in a 1-year gain of population life expectancy in 1 or more of every 200 cases in which it was applied. Alternatively, if the gain in diagnostic certainty by using immunohistochemistry was 10% and the value placed on a percentage gain in diagnostic certainty was $1000, immunohistochemistry was cost-effective if it produced this increase in certainty in 1 of every 40 tests. If a life-year was valued at $50 000, immunohistochemistry was cost-effective if it resulted in a change in patient prognosis of 0.5 years in 1 of every 100 tests.

CONCLUSIONS

Using theoretical modeling, immunohistochemistry is extremely cost-effective. These data have implications in an era of managed care when providers attempt to trim laboratory services. Additional studies are needed to evaluate the actual practice efficacy of immunohistochemistry.

Determination of lung as the primary site of cerebral metastatic adenocarcinomas using monoclonal antibody to thyroid transcription factor-1

Determining the primary site of a cerebral metastatic adenocarcinoma is complicated by the histologic similarity of most adenocarcinomas. Thyroid Transcription Factor-1 (TTF-1) is a highly specific marker of peripheral airway cell neoplasms. Formalin fixed tissue from 30 patients with brain metastasis whose primary sources were clinically and histologically known with certainty were analyzed for immunoreactivity to TTF-1. There were 18 cases of metastatic lung adenocarcinoma. Other metastases were from breast (6), colon (1), prostate (1), kidney (1), paranasal sinus (1), melanoma (1), and intestinal carcinoid (1). No patients with carcinoma of the thyroid were found. Positivity was regarded as intense nuclear reactivity. Twelve (67%) metastatic lung adenocarcinomas stained for TTF-1. None of the cerebral metastases from other body sites showed positivity. In addition, normal brain tissue and astrocytic tumors did not stain for TTF-1. These data show that TTF-1 is a highly specific and reasonably sensitive marker for peripheral airway cell metastasis to the brain.

Value of electron microscopy and immunohistochemistry in the diagnosis of soft tissue tumors

Light microscopy alone is often insufficient to type a soft tissue tumor. In this study 142 consecutive soft tissue tumors (benign or malignant), for which both electron microscopy (EM) and immunohistochemistry (IHC) had been performed, were reviewed to assess the contribution of these two modalities to making the final diagnosis. A tentative diagnosis (58 cases) or differential diagnosis (84 cases) was made following light microscopical examination. Ultrastructural and immunohistochemical features were then reviewed. Overall, EM more often contributed to diagnosing the tumor type than IHC (80 vs. 65%), with a statistically significant difference (p = .001). This was most apparent in high-grade sarcomas (grade III); the contribution of the two modalities was similar in benign and low-grade malignant tumors. IHC more often than EM (33% vs 22%) did not provide information to aid in typing of the tumor. However in 47% of the cases in which one of the two modalities was noncontributory, the other technique was helpful in reaching a diagnosis. These findings suggest that both IHC and EM are necessary to properly evaluate soft tissue tumors.

The status of immunohistochemical studies in lymphoma diagnosis

Immunohistochemical studies of formalin fixed paraffin embedded sections today constitute an essential component of the diagnostic process for malignant lymphoma. Lineage related markers are of value in distinguishing various lymphomas from anaplastic large and small cell carcinomas, and from sarcomas. Other more recently available markers are of value in establishing prognosis and, on occasion, in differentiating between neoplastic and reactive proliferations. Meticulous attention to reagent control and technical procedures is essential to all such studies.

Immunostaining of cell preparations: a comparative evaluation of common fixatives and protocols

Immunostaining of cytologic preparations has been beset by problems of inconsistency, high background staining, and the requirement of different fixatives for different antigens. This study sought to identify a universal fixative and a simple fixation protocol suitable for a wide range of tissue antigens commonly employed for cytologic diagnosis. In an analysis of 23 fixation protocols involving acetone, acetone/methanol, acetone/formalin, glutaraldehyde, ethanol, methanol, and formal saline, fixation in 0.1% formal saline overnight at 27 degrees C followed by 10 min fixation in 100% ethanol produced the most consistent and optimal preservation of immunoreactivity which could be further enhanced by pre-treatment with microwaves for epitope retrieval. Blocking of endogenous peroxidase was not necessary with this fixation protocol. Provided the smears were well air-dried (for at least 14 hr) prior to immersion in formal saline, there was no need to employ adhesive-coated glass slides. The smears could be kept at 27 degrees C (room temperature) for at least 7 days and at -70 degrees C for 5 wk without loss of immunoreactivity as air-dried smears or after fixation in formal saline. One hundred percent acetone and 100% ethanol produced good morphology and immunoreactivity but a high level of background staining, whereas acetone-based mixtures resulted in inconsistent immunostaining.

Intermediate- and low-molecular-weight keratin detection with the monoclonal antibody MNF116. An immunohistochemical study on 232 paraffin-embedded cutaneous lesions

Immunohistochemical detection of certain low to intermediate molecular weight keratins often is impaired in routinely processed specimens due to masking of these antigens by formalin fixation. Despite standard enzymatic digestion, AE1:AE3 and CAM 5.2, two of the most currently utilized antikeratin antibody preparations, either stain weakly or fail to stain basal keratinocytes and tumors composed of basaloid keratinocytes in paraffin sections of formalin-fixed tissue. We present here our experience with the monoclonal antibody MNF116 which detects keratins 5, 6, 8, 17, and 19 (DAKO, Carpinteria, CA). We have studied 232 routinely-processed skin lesions with MNF116 and compared the staining with that of AE1:AE3 mixture or CAM 5.2. In normal skin, the staining achieved with MNF116 was particularly strong on the basal cells of the epidermis and adnexae. MNF116 was positive in all 154 epithelial tumors and negative in all but one (a leiomyosarcoma) of 78 mesenchymal and melanocytic tumors. AE1:AE3 mixture was positive in all but four poorly-differentiated squamous cell carcinomas and it was only weakly positive in most basal cell carcinomas. CAM 5.2 was positive in tumors of the sweat apparatus, Merkel cell carcinomas, metastatic carcinomas, and 5/15 basal cell carcinomas. We consider that, in routinely processed specimens, MNF116 is very useful and convenient for detection of cytokeratin expression in cutaneous lesions, and therefore helpful in the evaluation of tumors with small cells and other poorly differentiated neoplasms of the skin.

Relative usefulness of electron microscopy and immunocytochemistry in tumour diagnosis: 10 years of retrospective analysis

AIMS

To determine retrospectively the relative usefulness of electron microscopy and immunocytochemistry for tumour diagnosis; to monitor the influence of new antibodies and antisera on the use of these techniques in one laboratory.

METHODS

During 1980 to 1989 inclusive, 726 tumours were examined by electron microscopy, 862 by immunocytochemistry, and 286 by both techniques. The choice of techniques and, for immunocytochemistry, the range of antibodies used were compared between each category of final diagnosis.

RESULTS

During the study period there was a sharp fall in the use of electron microscopy and a corresponding rise in immunocytochemistry. These trends applied to all categories of final tumour diagnosis, but the use of electron microscopy was sustained longer for lesions suspected or eventually confirmed to be melanomas or amine precursor uptake decarboxylation cell carcinoma (APUDomas)--for example, carcinoid tumours. The immunocytochemistry:electron microscopy use ratios ranged from 2.07:1 to 0.44:1 for the categories in which lymphoma and APUDoma, respectively, were the final diagnoses. The abandonment of electron microscopy for suspected or confirmed lymphomas and carcinomas corresponded to the increasing availability of relevant antisera and antibodies.

CONCLUSIONS

The wider application of immunocytochemistry for tumour diagnosis is endorsed, but electron microscopy should be retained for selected cases in which the results of immunocytochemistry might be predictably ambiguous or otherwise unhelpful.

The World Health Organization's Histological Classification of Salivary Gland Tumors. A commentary on the second edition

The second edition of the World Health Organization's Histological Classification of Salivary Gland Tumors is more extensive and detailed than the previous edition published 20 years ago. The new edition is based on data regarding newly described tumor entities and the behavior and prognosis of the previously classified tumors. The distinct morphologic features of monomorphic adenomas justify their separation for purposes of identification. Among the carcinomas, various types were distinguished for purposes of recognition, prognosis, and treatment. The term tumor was replaced by carcinoma in the following two entities: acinic cell carcinoma and mucoepidermoid carcinoma. The tumor-like lesions were described in more detail.

Selection of appropriate cellular and molecular biologic diagnostic tests in the evaluation of cancer

In this article, the use of cellular and molecular markers to diagnose and stage tumors is discussed. Their role in the evaluation of tumor prognosis and tumor susceptibility also is covered. The immunologic, cytogenetic, and molecular phenotype is discussed. Traditional markers are compared with newer methodologic approaches including evaluation of oncogenes, tumor suppressor genes, and genes that predict tumor susceptibility. These discussions are presented in relation to specific tumors. Finally, statements one might use to decide which tests to perform are presented.