Oestrogen receptor staining of paraffin-embedded breast carcinomas following short fixation in formalin: a comparison with cytosolic and frozen section receptor analyses

This paper describes an improved immunohistochemical method for demonstrating oestrogen receptor (OR) protein in paraffin-embedded sections of tissue fixed for 1.5 h in formalin. Thirty-two cases of infiltrating ductal breast carcinoma were stained with a monoclonal anti-OR antibody (H222), using a standard streptavidin-biotin method, following pretreatment with pronase. OR counts in paraffin sections were compared with those of frozen sections and with cytosolic values determined by a dextran-coated charcoal method. Twenty-seven of the carcinomas were OR-positive in paraffin sections. There was concordance between the paraffin section and the frozen section-determined receptor status in 30 cases (94 per cent) and a strong correlation was observed (r = 0.76; P less than 0.0001). Similarly, OR counts in paraffin sections correlated with cytosolic OR values (r = 0.60; P less than 0.001) and there was concordance in 97 per cent of cases. The percentage of positively-stained tumour cells in paraffin sections ranged from 0 to 94 per cent with staining intensities comparable to those seen in frozen sections. Staining of paraffin sections identified more OR-positive tumours than either frozen section staining or cytosolic assay. This study validates immunohistochemical OR analysis in formalin-fixed, paraffin-embedded breast carcinomas using a commercial anti-OR antibody.     

Immunocytochemical staining of progesterone receptor in paraffin sections of human breast cancers.

Monoclonal antibodies (mAB) against progesterone receptor (PR) and the peroxidase-antiperoxidase (PAP) method to visualize PR in paraffin sections from 68 human breast cancers were used. Ten mAB, which recognize human PR on frozen sections, were tested. Six could detect PR in paraffin sections, with Li 417, LET 456, and LET 126 giving the best results. LET 126 antibody was used for most further studies. The effects of fixation with picric acid-formaldehyde (PAF), buffered-formalin, or with Bouin solution were investigated; all fixation methods allowed PR immunolabeling, although PAF or buffered formalin usually gave the best results. Positive staining was seen in the nucleus of carcinoma cells. Variations in intensity and extent of immunoreactivity were observed in all sections and among different regions of the same specimen. These were probably related to the heterogeneity of the tumor cell population. Results were compared with the PR content in the respective tumor tissues, determined by steroid-binding assay, and with immunocytochemistry on frozen sections. It was shown that there were correlations between the immunocytochemical staining (positive or negative) and the steroid binding assay (80%) and between the immunocytochemical staining on paraffin sections and on frozen sections (78%). Weaker intensity and fewer number of PR-positive cells were found for paraffin-embedded tumors. Estrogen receptors were also detected on adjacent sections from the same paraffin-embedded tissues by use of monoclonal anti-ER antibodies (ERICA-kit[Abbott Laboratories, Chicago, IL]) and DNase pretreatment. In conclusion, this immunocytochemical method for detection of PR and ER on paraffin sections offers an alternative to frozen tissue. It allows histologic and immunocytochemical studies on the same sample and retrospective studies on stored tissue blocks.     

抗DESMOPLAKIN I单克隆抗体的制备

作者从水牛鼻表皮中分离桥粒,提取桥粒中的Desmoplakin I(DPI)。用DPI作免疫原,免疫BALB/C小鼠,建立了一株分泌抗DPI单抗的细胞AD-1。免疫组化染色证实,该单抗与上皮组织呈阳性反应,与非上皮性组织呈阴性反应。提示该单抗可作为区分上皮性肿瘤与非上皮性肿瘤的免疫组化探针。     

Immunohistochemical analysis of p53 protein expression in benign and malignant skin tumors using a panel of anti-p53 antibodies.

The expression of p53 in a variety of benign and malignant skin lesions has been first assessed in frozen sections and then compared with the results obtained in corresponding paraffin-embedded sections using various immunohistochemical staining methods with a panel of anti-p53 antibodies. Of the 48 benign and malignant skin lesions studied, 46(96%) had corresponding paraffin sections and immunohistochemical results obtained with DO7 on frozen and paraffin sections were concordant in 97%, qualitatively. Using streptavidin-biotin complex method, p53 was identified in 33% of dysplastic squamous lesions, 50% of squamous cell carcinomas (SCCs) and 36% of basal cell carcinomas (BCCs) on frozen section, whereas 25% of dysplastic squamous lesions, 40% of SCCs, and 32% of BCCs showed p53 positivity on paraffin-embedded sections. In frozen sections, the same regions of each specimen exhibited similar topographic patterns of positive immunoreactivity with both monoclonal antibodies, PAb 1801 and DO7. In contrast, immunohistochemical staining with polyclonal antibody, CM-1, gave poor morphologic resolution, although effective in paraffin-embedded sections.     

Enhanced polymer one-step staining (EPOS) for proliferating cell nuclear antigen (PCNA) and Ki-67 antigen: Application to intra-operative frozen diagnosis

Enhanced polymer one-step staining (EPOS) is a novel, highly sensitive one-step immunostaining method. This simple and rapid technlque was applied to intra-operattve frozen diagnosis. The markers of choice were proliferating cell nuclear anmen (PCNA) and Ki-67 antigen. These cell prollferation markers were both identifiable in fresh frozen see tions of the human tonsil In approximately 7 min. The suitable staining sequences are as follows. Frozen sections prepared using 3-aminopropyitimethoxysilane-cpated glass slides are immediately fixed, without air drying, for 15s in a mixture of 50% formalin and 50% methanol for PCNA, and in 10% formalln for Ki-67 antigen. After a brief rinse in phosphate-buffered saline (PSS), sections are incubated with the EPOS antibody for 3 min, followed by PBS rinse for 1 min. The peroxidase activity is visualized in diaminobenzidine-H₂O₂ solution containing 10mmol/L imidazole for 2 min. After a light rinse in tap water, the nuclei are briefly counterstained with 5% methyl green. When necessary, endogenous peroxi-dase blockage in 1% periodic acid solution for 1 min is added before the EPOS antibody incubation. This procedure is applicable to frozen sections of gastric cancers, malignant lymphomas, and brain, liver and peritoneal lesions in which differential diagnosis between benignancy and malignancy was required.     

A comparison of methods for the detection of human papillomavirus DNA by in situ hybridization with biotinylated probes on human carcinoma cell lines. Application to wart sections

We compared nine different techniques for the detection of biotinylated DNA-DNA HPV hybrids on HeLa cells with 10-50 copies of HPV 18 DNA per cell. CaSki cells with 600 copies of HPV 16 DNA per cell and tissue sections from frozen or paraffin-embedded biopsy specimens. The cell samples were either cell deposits or cytocentrifuged or cultured slides. In most cases, the samples (cell deposits and tissue sections) were denatured with hybridization mixture prepared under stringent conditions (Tm = -17 degrees C) containing biotinylated DNA probes (cloned HPV types 1, 2, 6, 11, 16 and 18), at 90 degrees C for 10 min. In other cases (cytocentrifuged or cultured cells), the denaturation was performed by HCl hydrolysis and mild heating at 50 degrees C; the probes were denatured separately by heating. All the samples were further incubated overnight at 37 degrees C. For HPV DNA detection, three amplification levels were used on cell deposits. Only the techniques involving a three-step reaction (a rabbit anti-biotin antibody - a biotinylated goat anti-rabbit antibody - a complex of streptavidin-alkaline phosphatase or streptavidin-gold or streptavidin-fluorescein) gave satisfactory results, on both cell lines. With the one step reaction (an avidin-horseradish peroxidase, or streptavidin-alkaline phosphatase or streptavidin-fluorescein complex), no labeling of HeLa cells was observed with any of the HPV probes, including HPV 18. The techniques involving four steps (avidin or streptavidin - anti-avidin goat antibody or anti-streptavidin rabbit antibody - a biotinylated anti-goat (or anti-rabbit) antibody - a complex of avidin-biotin-peroxidase or streptavidin-biotin-alkaline phosphatase or streptavidin-biotin-horseradish peroxidase) resulted in high background on both cell lines. For the reproducible detection of low copy number of HPV DNA (less than 50 copies) such as occur in HeLa cells our data suggested that the three-step technique with the streptavidin-alkaline phosphatase complex was the method of choice. The most intense labeling was always obtained with cell deposits and the technique was successfully applied to frozen and paraffin-embedded tissue sections from typical warts.     

Growth fraction estimation of malignant lymphomas in formalin-fixed paraffin-embedded tissue using anti-PCNA/Cyclin 19A2. Correlation with Ki-67 labeling.

The immunohistochemical detection of PCNA/Cyclin, a nuclear protein associated with cell proliferation, represents a potentially useful tool for the study of tumor proliferative activity. Previous studies investigating the reactivity of anti-PCNA/Cyclin monoclonal antibody 19A2 have not clearly defined the population of proliferating cells with which 19A2 reacts in tissue sections. The authors describe a method for detection of PCNA/Cyclin in formalin-fixed, paraffin-embedded tissue using a routine biotin-streptavidin immunohistochemical system that employs an anti-IgM, mu-chain-specific second-stage antibody. The authors used this method to study the proliferative activity of 24 malignant lymphomas, consisting of 12 low-grade lymphomas (LGLs) and 12 intermediate-grade lymphomas (IGLs), and five reactive tonsils. 19A2 data was compared with Ki-67 labeling in frozen sections in the same group of cases. 19A2 provided easily detectable nuclear staining of proliferating cells with reactive cells demonstrating varying intensity of staining, this latter finding most likely due to the varying nuclear concentration of PCNA/Cyclin protein during the cell cycle. In tonsils, 19A2 reacted with germinal center cells and basal keratinocytes. In the malignant lymphomas, there was good correlation between 19A2 and Ki-67 data (r = 0.90, P less than 0.001). The subgroup of LGLs showed a mean PCNA/Cyclin of 26% and a mean Ki-67 of 28%. In the subgroup of IGLs, mean PCNA/Cyclin = 54% and mean Ki-67 = 59%. These results indicate that 19A2 detects a fraction of proliferating cells that is similar to that detected by Ki-67, ie, the growth fraction, and that 19A2 is a reliable marker of proliferative activity in uniformly handled, formalin-fixed, paraffin-embedded tissue.     

Hyalinizing trabecular adenoma of the thyroid: Its unusual cytoplasmic immunopositivity for MIB1

The monoclonal antibody Ki-67 reacts with a human nuclear cell proliferation-associated antigen that is expressed in all active parts of the cell cycle and is well established as a marker of cell proliferation. However, the Ki-67 method requires fresh frozen material. Recently, MIB1 has been reported to give an immunohistochemical staining pattern identical to Ki-67 on paraffin-embedded tissue sections, frozen sections and cytological samples_? This proliferation-associated antigen is apparently localized in the nucleus. Recently, we performed immunohistochemical staining using the monoclonal MIB1 antibody upon a variety of tumors and non-neoplastic conditions of the thyroid. Tumor cells of hyalinizing trabecular adenoma revealed an intense cytoplasmic immunopositivity for MIB1. In contrast, cytoplasmic immunostaining for MIB1 was negative in all other thyroid tumors and non-neoplastic lesions. Because of this unusual staining pattern, we repeated the staining of all cases and found the results to be reproducible. Therefore, we believe that positive cytoplasmic immunostaining for MIB1 is a characteristic finding of hyalinizing trabecular adenoma and is useful in differentiating it from other thyroid tumors.     

DEVELOPMENT OF AN OPTIMAL PROTOCOL FOR ANTIGEN RETRIEVAL: A ‘TEST BATTERY’ APPROACH EXEMPLIFIED WITH REFERENCE TO THE STAINING OF RETINOBLASTOMA PROTEIN (pRB) IN FORMALIN-FIXED PARAFFIN SECTIONS

The retinoblastoma (RB) gene, which encodes the nuclear RB protein (pRB), is believed to be involved in cell cycle control and cell differentiation. Studies have demonstrated that loss of RB function may play a role in tumour formation and progression of a variety of human tumours, such as bladder, lung, breast, and prostate cancers. The immunohistochemical detection of pRB expression in formalin–paraffin sections of human cancer has potential advantages of convenience, economy, and compatibility with routine surgical pathology practice. In practice, however, results using pRB antibodies on routinely processed, paraffin-embedded tissue have been inconsistent. In this study, the antigen retrieval (AR) method has been applied to the immunohistochemical detection of pRB in paraffin-embedded tissues and a ‘test battery’ approach has been developed to identify the principal variables that result in the optimal AR protocol. This approach includes the use of buffered solutions at pH 1, 6, and 10 with three different heating conditions (temperatures 120°C, 100°C, and 90°C). In the example described here with antibody RB-WL-1, the low pH solution with the microwave heating at 100°C proved most effective. Both fresh and routinely processed formalin–paraffin tissues of normal and bladder carcinoma were used for a comparison of the pRB immunostaining. The AR method was evaluated by comparing the immunohistochemical staining result on routinely processed formalin–paraffin sections with frozen sections of the same tumour. A consistent intensity of immunohistochemical staining for pRB was achieved using the identified optimal AR protocol on formalin–paraffin sections. All slides showed positive staining of pRB in normal mesenchymal and epithelial tissues. The pattern of pRB localization and intensity of staining was similar to that obtained in frozen sections, though the intensity obtained by AR treatment on paraffin sections was slightly to moderately stronger than that obtained in frozen sections. Once the protocol was identified, it was tested using routinely processed paraffin tissue sections of 245 cases of bladder carcinoma, with consistent pRB immunostaining results. The protocol described is simple to perform and gives reproducible results for evaluation of pRB expression by immunohistochemistry.     

固定液浓度与固定时间对人乙酰胆碱受体抗体与大鼠神经元-nAchR之间免疫结合反应的影响

目的探讨进行膜受体免疫组化染色的标本制备时应采用的合适固定液浓度和固定时间,以提高反应的敏感性和稳定性.方法在不同固定液浓度和固定时间固定的脑切片,用免疫组织化学法显示人乙酰胆碱受体抗体(AchRab)与大鼠膜受体AchR的免疫结合反应.结果4%多聚甲醛灌注固定0.5 h且不经后固定组的染色结果最好,受体的免疫组化染色深,细胞数量多,突起长,其它组均不如这一组结果满意.结论用免疫组化检测膜受体时,应采用4%多聚甲醛灌注固定0.5 h且不后固定的固定方法.     

HLA-DR Antigen on Human Trophoblast*

ABSTRACT: To assess the presence of human leukocyte antigens (HLA) on first trimester human trophoblast cells, frozen sections of villous trophoblast and monolayer cultures of isolated cells from placental villi were prepared and exposed to a mouse monoclonal antibody directed against HLA-DR and then incubated with fluorescein-conjugated goat anti-mouse antibodies. Fluorescence microscopy demonstrated that HLA-DR antigens were present on only the small polygonal epithelioid cells of the monolayer culture. The crescentic staining pattern was consistent with widespread distribution of antigen on the cell membrane. There was no staining over giant multinucleated structures or on fibroblasts of such cell cultures. No HLA-DR was detected when this indirect immunofluorescent technique was applied to tissue sections of villous trophoblast. Existence of high concentrations of hCG in culture supernatants and coincident localization of both hCG and HLA-DR using antibodies conjugated with rhodamine or fluorescein on the polygonal epithelioid cells indicate the trophoblastic origin and expression of HLA-DR antigen under in vitro monolayer culture conditions.     

In vivo immunohistochemical identification of tumor necrosis factor/cachectin in human lymphoid tissue.

To find an alternative approach to the in vivo detection of tumor necrosis factor/cachectin (TNF alpha), an immunohistochemical method to identify TNF alpha in histologic sections was developed. This method employs the streptavidin-biotin immunoperoxidase technique, and TNF alpha-specific monoclonal and polyclonal antibodies, on cryostat sections of fresh frozen human lymphoid tissue. Staining was evident in most specimens displaying follicular hyperplasia, but was absent from histologically normal tissue. Both tingible body macrophages and follicular dendritic reticulum cells appeared from phenotype analysis in serial sections and by double staining experiments to constitute the main source of TNF alpha. This technique complements other systemically oriented assays that may fail to detect significant in vivo TNF alpha production and activity at a cellular level.     

结节病肉芽肿构成细胞内空气细颗粒物的观察

目的探讨空气细颗粒物（PM2．5）与结节病之间的关系。方法收集下列病例的石蜡包埋组织标本：结节病49例，因肺外疾病死亡的成人尸检肺标本10例，胎儿尸检肺标本10例。标本行（1）HE染色，观察肉芽肿及尘细胞；（2）Warthin—Starry（W—S）银染色，显示细胞内的PM2．5；（3）免疫组化染色标记肉芽肿和尘细胞；（4）制作超薄切片，在透射电镜下观察证实细胞内的PM2．5。结果经W—S染色，在结节病肉芽肿细胞内观察到明显的PM2．5，并在电镜观察中得到进一步的证实，肉芽肿细胞和尘细胞CD68抗体标记阳性。结论结节病肉芽肿细胞内有PM2．5，为结节病空气颗粒物相关学说提供了形态学证据，提示结节病可能与PM2．5有关。     

Comparative study for the detection of peritubular capillary C4d deposition in human renal allografts using different methodologies

Detection of peritubular capillary (PTC) C4d deposition in tissue sections of renal allograft biopsies became an important aid in the diagnosis of antibody-mediated rejection. Pathologists in many major transplant centers now routinely stain renal allograft biopsies for C4d. Currently, there are 3 commercially available antibodies. Two of these antibodies are monoclonal and are usually used with either a 3- or a 2-step indirect immunofluorescence (IF) methodology on frozen sections. A polyclonal antibody is used on formalin-fixed, paraffin-embedded tissue section with an immunoperoxidase detection system. The goal of our study was to compare these antibodies and methodologies in our renal allograft biopsy material. Twenty renal allograft biopsies with diffuse or focal PTC C4d staining, using immunofluorescence methods on frozen sections, were selected for this study. These biopsies were tested with the 3 commercially available anti-C4d antibodies (Biogenesis, Brentwood, Calif, cat no. 222-8004; Quidel Corporation, Santa Clara, Calif, cat no. A213; and ALPCO Diagnostic, Windham, NH, cat no. 004-BI-RC4D). Both monoclonal antibodies (Biogenesis and Quidel) were tested with a 3- and a 2-step indirect IF method on frozen sections. The polyclonal antibody (ALPCO) was applied to formalin-fixed paraffin sections using immunoperoxidase methodology. In selected cases, the polyclonal antibody was tested on frozen sections with a 3-step indirect IF method. To exclude possible false-negative staining with the IF method, we selected 10 additional biopsies that showed PTC margination of inflammatory cells, but were C4d-negative or only focally positive, and tested them with the ALPCO antibody on paraffin sections. We have found that all methodologies and antibodies tested provided adequate results with only minor differences between them. Perhaps the most sensitive method is the 3-step indirect IF on frozen sections using one of the monoclonal antibodies. We prefer the 2-step indirect IF method with the Quidel monoclonal antibody because of its simplicity, quick turnaround time, and relatively low cost. The advantages and disadvantages of the individual methodologies are discussed.     

Enhanced staining for Leu M1 (CD15) in Hodgkin's disease using a secondary antibody specific for immunoglobulin M.

The utility of staining for Leu M1 (CD15) as a diagnostic aid in Hodgkin's disease has been questioned because of a relative lack of specificity and sensitivity. Furthermore, interpretation is often made difficult by staining that tends to be weak and focal. Because the murine monoclonal anti-Leu M1 antibody is of immunoglobulin M type, it is reasonable to wonder whether improved immunohistochemical staining might result from use of a secondary goat antibody specific for the mouse mu heavy chain instead of the traditional one against mouse immunoglobulin. The two methods were compared, using a biotin-avidin detection system, on paraffin sections from 15 cases of Hodgkin's disease: 9 nodular sclerosing, 1 mixed cellularity, and 5 of nodular lymphocytic and histiocytic (L&H) type. In the nodular sclerosing/mixed cellularity group, the mu-specific detection method resulted in a greater number of cases with reactive Hodgkin's cells (7 versus 5), stained an average of more than three times as many neoplastic cells in each case (49% versus 14%), and usually produced staining that was distinctly more intense, often in a membrane and paranuclear distribution characteristic of Leu M1 in Hodgkin's cells. In the noLeu M1 in Hodgkin's cells. In the nodular L&H group, 1 case showed weak, focal staining with the newer method. None of the L&H cases stained using the traditional technique. It is concluded that use of a second-stage antibody that is directed specifically against mu heavy chains results in an improvement in immunohistochemical staining for Leu M1 in paraffin sections, which is of practical significance.     

Detection of avian encephalomyelitis viral antigen with a monoclonal antibody

A monoclonal antibody (MAb), designated VR9-1, prepared against avian encephalomyelitis virus (AEV) reacted with the embryo-adapted strain, Van Roekel, two vaccine and two field strains in indirect immunofluorescent and immunoperox-idase staining of frozen sections of chicken brain, chicken embryo fibroblast and brain cells inoculated with each virus. The MAb was also used as a detector in avidin-biotin-peroxidase staining in paraffin sections where results indicate that it recognized a common epitope among strains of AEV and may be useful for detection and quantitative studies.     

An immunocytochemical method for demonstrating estrogen receptor in human uterus using monoclonal antibodies to human estrophilin

We have used monoclonal antiestrophilin antibodies to develop an improved immunocytochemical method for localizing estrogen receptors in tissue sections with an indirect immunoperoxidase technique. Rat monoclonal antibodies were raised against human estrogen receptor (estrophilin) protein derived from the cytosol of MCF-7 human breast cancer cells. These monoclonal antibodies have been shown to have extensive cross-reactivity with estrogen receptors from various primate and nonprimate tissues. We have used frozen sections of human proliferative phase endometrium and an indirect immunoperoxidase technique to establish conditions for demonstrating estrogen receptor antigenic determinants in frozen tissue sections. The method involves (a) brief fixation with formaldehyde-containing fixatives either prior to freezing or immediately after cutting cryostat sections, (b) bleaching the tissue of endogenous peroxidase activity, (c) application of primary antibody or control immunoglobulin, (d) application of an adsorbed bridging antibody (goat antirat IgG), and (e) application of rat peroxidase-antiperoxidase followed by diaminobenzidine. Specific nuclear staining for estrogen receptor antigenic determinants was observed in the vast majority of epithelial and stromal cells. No specific cytoplasmic staining was identified in cryostat sections of any of the 17 cases studied for this report.     

A rapid immunohistologic method for determining the limit of cancer invasion at the surgical margin of scirrhous carcinoma of the stomach during surgery

The authors used the monoclonal antibody (MAb) S202 as an adjunct for detection of scirrhous gastric carcinoma cells in cytomorphologic preparations of the resected stomach. Twenty-six samples of scirrhous gastric cancer were stained by the avidin-biotin complex technique on fixed frozen sections. MAb S202 was strongly reactive on all sections. In 12 cases, samples obtained from surgical margins were examined by a rapid immunostaining method. In one case, conventional cytologic findings were equivocal, whereas by the rapid immunostaining method single cells were stained darkly, indicating malignancy. Thus, immunohistochemical analysis using MAb S202 should be carried out to determine the limit of invasive carcinoma at the time of surgery.     

Receptor-targeted quantum dots: fluorescent probes for brain tumor diagnosis

The intraoperative diagnosis of brain tumors and the timely evaluation of biomarkers that can guide therapy are hindered by the paucity of rapid adjunctive studies. This study evaluates the feasibility and specificity of using quantum dot-labeled antibodies for rapid visualization of epidermal growth factor receptor (EGFR) expression in human brain tumor cells and in surgical frozen section slides of glioma tissue. Streptavidin-coated quantum dots (QDs) were conjugated to anti-EGFR antibodies and incubated with target cultured tumor cells and tissues. The experiments were conducted first in human glioma tumor cell lines with elevated levels of EGFR expression (SKMG-3, U87) and then in frozen tissue sections of glioblastoma multiforme and of oligodendroglioma. The bioconjugated QDs used in the study were found to bind selectively to brain tumor cells expressing EGFR. QD complexed quickly to the cell membrane (less than 15 min), and binding was highly specific and depended on the expression level of EGFR on the cell membrane. Tissue experiments showed that only tumor specimens expressing EGFR were labeled in less than 30 min by QD complexes. These findings demonstrate that QD-labeled antibodies can provide a quick and accurate method for characterizing the presence or absence of a specific predictive biomarker.     

Demonstration of estrogen receptor by immunohistochemical staining in paraffin sections of breast carcinoma

Paraffin embedded sections of 64 breast carcinomas were stained immunohistochemically using a commercially available monoclonal antibody to estrogen receptor. To improve the sensitivity of the staining, the authors used a Pronase enzyme pretreatment, biotinylated antibody to rat IgG as secondary antibody, streptavidin-alkaline phosphatase as tertiary reagent and fast red as chromogen. When compared to the results of estrogen receptor enzyme immunoassay, this method yielded an 85.9% concordance rate, 86.2% specificity and 85.7% sensitivity. When compared to estrogen receptor immunocytochemistry(ER-ICA) in frozen section and considering the inherent advantages of immunohistochemical staining over biochemical assay, the major advantages of this method are good morphology, suitability for retrospective study and reduced cost of staining due to dilution of expensive primary antibody. Thus, this method offers an alternative to ER assay using fresh tissue and should provide additional valuable information about estrogen receptor.