Diagnostic Immunohistochemistry: what can go wrong?

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

Protein and gene expression of estrogen receptor alpha and nuclear morphology of two breast cancer cell lines after different fixation methods

We assessed morphology and ERalpha protein and gene expression of two breast cancer cell lines after three different fixatives: neutral-buffered 10% formaldehyde, LN-FIX and FineFIX and varying fixation times. We found that the cell morphology was best preserved in cells fixed with LN-FIX. Two commercial fixatives used in this study shrank cells less than formalin. In immunohistochemical assay samples were stained with two different ERalpha antibodies, clone 1D5 and clone SP1. All tested fixatives were suitable for immunohistochemistry. Staining was more intensive and the number of stained cells was larger with the clone 1D5 than with the clone SP1. Our gene expression analysis showed that formalin and LN-FIX preserve the ERalpha better than FineFIX, which is advertised to be optimal for molecular analysis. Our study suggests that tissues fixed with formalin are suitable also for molecular biology assays. This makes possible to research formalin-fixed paraffin-embedded archival tissues also with molecular techniques.

Effects of prolonged formalin fixation on diagnostic immunohistochemistry in domestic animals

Immunohistochemistry (IHC) is routinely used in diagnostic pathology to detect infectious agents, to immunophenotype neoplastic cells, and to prognosticate neoplastic diseases. Formalin fixation is considered a limiting factor for IHC because formalin can cross-link antigens and mask epitopes. Prolonged formalin fixation is presumed to result in decreased antigen detection; however, this effect has only been evaluated with a few antibodies. The goal of this study was to evaluate the effect of prolonged formalin fixation on the immunohistochemical detection of 61 different antigens. Approximately 5-mm-thick tissue slices were fixed in 10% neutral-buffered formalin. Tissue slices were removed from formalin, processed, and paraffin-embedded at 1-day, 3-day, and then at approximately 1-week intervals. IHC was performed on all sections in tandem after all tissues were processed. Immunoreactions were evaluated by three pathologists according to a four-tier grading system. Immunoreactivity of cytokeratin 7, high-molecular-weight cytokeratin, and laminin was diminished by prolonged formalin fixation. However, immunohistochemical reactivity remained moderate to strong with up to 7 weeks of fixation for all other antibodies. These results suggest that prolonged formalin fixation has minimal effects on antigen detection for most commonly used antibodies. These results further validate the use of IHC in diagnostic pathology.

Pattern and spectrum of morphology referrals in breast pathology consultation

AIMS

We aimed to identify common reasons for second opinion breast pathology referrals at the Pathology Department, Singapore General Hospital, focusing on queries and diagnostic issues raised by referring clinicians and pathologists.

METHODS

Request forms for breast pathology consultations were retrieved from a specialist's correspondence files consisting of pathologists' referrals, and from centralised laboratory records, comprising clinician-initiated referrals. Clinical and histomorphological queries raised by the referrals were collated.

RESULTS

Of 299 cases evaluated, clinician-initiated referrals (n = 137, 46%) included requests for review of overall histopathology to confirm carcinoma subtype (n = 47), grade (n = 2), size (n = 4), lymphovascular invasion (n = 1) and confirm hormonal receptor and c-erbB-2 assays (n = 33). Also required were: comparison of recurrent with previous lesions (n = 8); settling discrepant diagnoses between two or more prior pathology reports (n = 4); verification of microinvasion (n = 6), in situ carcinomas (n = 6) or atypical ductal hyperplasias (n = 4); delineation of benign (n = 8) and spindle cell lesions (n = 3); to establish a breast origin of metastatic lesions (n = 5); and distinction of carcinoma from lymphoma (n = 2). Pathologist-initiated referrals (n = 162, 54%) sought arbitration between borderline proliferative lesions (n = 46) and papillary lesions (n = 34); verification of microinvasion (n = 23), stromal lesions (n = 16), and carcinoma subtype (n = 13), especially if the patient was young (n = 5); clarification of metaplastic changes (n = 4) and lobular neoplasia (n = 8); and comparison of fibroepithelial lesions (n = 11).

CONCLUSIONS

Clinicians sought a second opinion mainly to verify histological diagnoses and report important pathological details for staging and confirmation of hormonal receptor and c-erbB-2 status prior to therapy. Borderline breast lesions are worrisome for both clinicians and pathologists in view of implications for management.

Quantification of diverse subcellular immunohistochemical markers with clinicobiological relevancies: validation of a new computer-assisted image analysis procedure

Tissue microarray technology and immunohistochemical techniques have become a routine and indispensable tool for current anatomical pathology diagnosis. However, manual quantification by eye is relatively slow and subjective, and the use of digital image analysis software to extract information of immunostained specimens is an area of ongoing research, especially when the immunohistochemical signals have different localization in the cells (nuclear, membrane, cytoplasm). To minimize critical aspects of manual quantitative data acquisition, we generated semi-automated image-processing steps for the quantification of individual stained cells with immunohistochemical staining of different subcellular location. The precision of these macros was evaluated in 196 digital colour images of different Hodgkin lymphoma biopsies stained for different nuclear (Ki67, p53), cytoplasmic (TIA-1, CD68) and membrane markers (CD4, CD8, CD56, HLA-Dr). Semi-automated counts were compared to those obtained manually by three separate observers. Paired t-tests demonstrated significant differences between intra- and inter-observer measurements, with more substantial variability when the cellular density of the digital images was > 100 positive cells/image. Overall, variability was more pronounced for intra-observer than for inter-observer comparisons, especially for cytoplasmic and membrane staining patterns (P < 0.0001 and P = 0.050). The comparison between the semi-automated and manual microscopic measurement methods indicates significantly lower variability in the results yielded by the former method. Our semi-automated computerized method eliminates the major causes of observer variability and may be considered a valid alternative to manual microscopic quantification for diagnostic, prognostic and therapeutic purposes.

Suggested Guidelines for Immunohistochemical Techniques in Veterinary Diagnostic Laboratories

This document is the consensus of the American Association of Veterinary Laboratory Diagnosticians (AAVLD) Subcommittee on Standardization of Immunohistochemistry on a set of guidelines for immunohistochemistry (IHC) testing in veterinary laboratories. Immunohistochemistry is a powerful ancillary methodology frequently used in many veterinary laboratories for both diagnostic and research purposes. However, neither standardization nor validation of IHC tests has been completely achieved in veterinary medicine. This document addresses both issues. Topics covered include antibody selection, fixation, antigen retrieval, antibody incubation, antibody dilutions, tissue and reagent controls, buffers, and detection systems. The validation of an IHC test is addressed for both infectious diseases and neoplastic processes. In addition, storage and handling of IHC reagents, interpretation, quality control and assurance, and troubleshooting are also discussed. Proper standardization and validation of IHC will improve the quality of diagnostics in veterinary laboratories.

Application of immunohistochemistry to liver and gastrointestinal neoplasms: liver, stomach, colon, and pancreas

CONTEXT

Immunohistochemistry has become an integral component of the practice of pathology. Newer antibodies allow for increasingly precise diagnoses for tumors that previously could not be easily identified. Recently, immunohistochemical evaluations have begun to allow pathologists to actively assist in determining prognosis and even in selecting therapies.

OBJECTIVE

To summarize the usefulness of currently available immunostains for the study of liver and gastrointestinal system neoplasms and to make recommendations for panels of immunostains that can be particularly helpful.

DATA SOURCES

Information has been collected from recent literature as well as from personal experience and practice.

CONCLUSIONS

Many immunostains are now available for the practicing pathologist that allow for increasing accuracy in diagnosis of liver and gastrointestinal tract neoplasms. Panels of immunostains can be used to differentiate between various tumors and also to identify site of origin in the case of a metastatic neoplasm. Immunostains that allow for prognostic determinations and for guidance in the selection of chemotherapeutic agents can also be used by pathologists to assist in the management of patients with malignant tumors affecting the liver and gastrointestinal tract.

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.