Biomedical subjects

Anthony S-Y Leong

Publications and source records attributed to Anthony S-Y Leong.

17 recordsLinked to original sources

PubMed2006

Calretinin, CD34, and alpha-smooth muscle actin in the identification of peritoneal invasive implants of serous borderline tumors of the ovary.

The correct identification of invasive implants in the peritoneum in serous borderline tumors (SBTs) of the ovary is an important determinant of diagnosis, treatment, and prognosis. Although the histologic criteria to distinguish noninvasive from invasive implants have been defined, the distinction can still be difficult. We examined the presence and distribution of mesothelial cells, stromal fibrocytes, and myofibroblasts in invasive and noninvasive peritoneal implants in 100 noninvasive, 100 invasive, and 100 metastatic nests/foci from 20 cases of SBTs with peritoneal implants, 10 serous carcinomas with peritoneal metastasis, and 10 cases of endosalpingiosis by immunostaining for calretinin, CD34, and alpha-SMA. All 100 invasive nests from seven SBTs and all 100 metastatic nests from the cases of serous carcinoma showed loss of calretinin+ mesothelial cells and stromal CD34+ fibrocytes around the nests. In contrast, 72/100 noninvasive nests displayed the presence of mesothelial cells around the nests and 68 displayed preservation of surrounding stromal fibrocytes. Alpha-smooth muscle actin positive myofibroblasts were present as a stromal response in 100/100 metastatic nests, 100/100 invasive nests and 54/100 noninvasive nests. The loss of mesothelial cells and stromal fibrocytes surrounding invasive nests together with a proliferation of myofibroblasts as demonstrated by immunostaining proved to be a sensitive and specific tool to separate invasive from noninvasive implants and represents an important adjunct to morphologic diagnosis. Combined sensitivity and specificity of the three antibodies was 100 and 81%, respectively. These methods, however, may not be helpful for small biopsies of noninvasive desmoplastic implants. The distribution of these cells provides some insights into the histogenesis of invasive and noninvasive implants in SBTs.

Actins↗

PubMed2006

Immunohistological localisation of human FAT1 (hFAT) protein in 326 breast cancers. Does this adhesion molecule have a role in pathogenesis?

AIMS: To examine the immunohistological expression in human breast cancers of human FAT1 (hFAT) protein, a recently described member of the cadherin superfamily, and its correlation with histological type and grade. METHODS: A total of 326 cases of invasive and in situ breast cancer representing a broad spectrum of histological subtypes were immunostained with affinity-purified rabbit antibodies produced to the cytoplasmic region of hFAT using a standard avidin-biotin system. Staining intensity was arbitrarily graded on a scale of 0 to 3. RESULTS: All tumours showed diffuse staining for hFAT. Immunoexpression of the protein was generally strong in both lobular (LCIS, n = 2) and ductal in situ carcinoma (DCIS, n = 55). hFAT was also strongly immunoexpressed in all types of invasive carcinoma. Grade 3 DCIS displayed the highest hFAT intensity compared with lower grade tumours, with significant differences between grade 1 and 3 (p = 0.015) and grade 2 and 3 (p = 0.047). With invasive ductal carcinomas (n = 128) the difference was not as clear-cut, as most tumours showed moderate (n = 63) or strong staining (n = 49), although grade 3 IDC revealed significantly decreased immunoexpression compared with grade 1 IDC (p = 0.03). CONCLUSIONS: The results illustrate that hFAT1 does not display the pattern of expression seen with the E-cadherin-ss-catenin adhesion complex; however, its over-expression and diffuse expression in both in situ and invasive carcinoma strongly suggests a role in carcinogenesis. From the known functions of FAT1 it is suggested that the concurrent loss of classical cadherins from cell-cell junctions accompanied by increased FAT1 expression contributes to loss of duct formation, and increased cell migration and invasion.

Biomarkers, Tumor↗

PubMed2006

Cytokeratin 20 and Ki-67 to distinguish carcinoma in situ from flat non-neoplastic urothelium.

Urothelial carcinoma in situ (CIS) is a high-grade neoplasm and an indicator of recurrence and progression that requires specific treatment. The distinction of CIS from flat non-neoplastic urothelium, in particular dysplasia, on the basis of histologic features is often difficult, and this study aims to validate cytokeratin 20 (CK20) and Ki-67 as discriminatory markers for this purpose. Immunostaining of these markers was applied to 26 cases of CIS, 14 atypia of unknown significance, 4 dysplasia, 6 normal, and 9 hyperplastic urothelium. CIS showed CK20 staining of deep urothelial cells in 23/26 CIS compared with restricted staining in surface cells in all non-neoplastic lesions. CIS had significantly increased Ki-67 index with a mean of 53.37% compared with that of non-neoplastic urothelium, which was <10% (P<0.0001). The proliferating cells were distributed randomly in CIS, whereas in non-neoplastic urothelium, staining was confined to the basal layer. Among the cases of atypia, 3/14 displayed deep staining for CK20 and 6/14 had elevated Ki-67 counts. In dysplasia similar findings were present in 1/4 and 2/4 cases, respectively. These findings suggest that CK20 and Ki-67 are objective markers to distinguish CIS from non-neoplastic urothelium. In cases of "atypia of unknown significance" and "dysplasia," positivity for both markers should raise the possibility of CIS or preneoplastic change and identify those cases for follow-up.

Biomarkers, Tumor↗

PubMed2006

Refinement of immunohistologic parameters for Her2/neu scoring validation by FISH and CISH.

The conventional method of scoring Her2/neu immunostaining is recognized to result in a high false-positive rate among 2+ cases when compared with results obtained with fluorescence in situ hybridization (FISH); however, costs and convenience dictates that immunohistochemistry remains the screening test for Her2/neu status in patients with breast cancer. We describe refined criteria for scoring of Her2/neu on the basis of anatomic localization rather than the subjective assessment of intensity. The presence of a circumferential tram track pattern that results from the staining of apposing cell membranes in >25% of the tumor cells was necessary for a 3+ score (Her2/neu overexpressed) and the presence of the tram track pattern in <25% was scored 2+ (equivocal); granular and fragmented membrane staining was scored 1+ (negative). The tram track pattern of Her2/neu overexpression showed 100% concordance with gene amplification. FISH and CISH testing in selected cases from the other categories validated the revised scoring method. These criteria reduced the numbers of equivocal staining cases that required FISH testing.

Biomarkers, Tumor↗

PubMed2006

Controversies in the assessment of HER-2: more questions than answers.

Human epidermal growth factor receptor 2 (HER-2) is over-expressed in 15% to 30% of breast cancers and is a poor prognostic marker in node-positive patients. HER-2 expression is an indicator of greater sensitivity to anthracycline-based chemotherapy and is the major criterion for selection for treatment with the anti-HER-2 antibody trastuzumab (Herceptin). Fluorescence in situ hybridization and immunohistochemistry (IHC) are the 2 most commonly used methods for detection of the gene and protein, respectively. Criticisms have been levied at the IHC method of identifying HER-2 overexpression but convenience and costs of this technique cannot be overlooked. Modifications to the IHC technique and scoring accommodate for many of the problems that derive from variables in preanalytical and analytic factors that influence results but standardization is currently impossible to attain. Deficiencies in fluorescence in situ hybridization assay also exist and alternative molecular methods of assay are explored in this review.

Biomarkers, Tumor↗

PubMed2005

Multiple organ infection and the pathogenesis of SARS.

After >8,000 infections and >700 deaths worldwide, the pathogenesis of the new infectious disease, severe acute respiratory syndrome (SARS), remains poorly understood. We investigated 18 autopsies of patients who had suspected SARS; 8 cases were confirmed as SARS. We evaluated white blood cells from 22 confirmed SARS patients at various stages of the disease. T lymphocyte counts in 65 confirmed and 35 misdiagnosed SARS cases also were analyzed retrospectively. SARS viral particles and genomic sequence were detected in a large number of circulating lymphocytes, monocytes, and lymphoid tissues, as well as in the epithelial cells of the respiratory tract, the mucosa of the intestine, the epithelium of the renal distal tubules, the neurons of the brain, and macrophages in different organs. SARS virus seemed to be capable of infecting multiple cell types in several organs; immune cells and pulmonary epithelium were identified as the main sites of injury. A comprehensive theory of pathogenesis is proposed for SARS with immune and lung damage as key features.

Adult↗

PubMed2005

Diagnostic pathology of lymphoproliferative disorders.

The last 20 years have seen a dramatic change in the way we classify, and therefore diagnose, lymphoma. Two decades ago, the International Working Formulation enabled diagnosis and management on the basis of H&E sections alone, with no mandatory requirement for immunophenotyping, molecular studies or any other ancillary investigations. The concept of categorisation by 'clinicopathological entities' defined by clinical features, morphology, immunophenotype and more recently, genotype, began with the Kiel, and Lukes and Collins classifications in the late 1970s, becoming fully expressed in the REAL and subsequently WHO classifications. The current, multidisciplinary approach to categorisation adds significantly to the task facing the anatomical pathologist, since it requires distribution of biopsy material to all the appropriate specialised laboratories, the gathering of a range of cross-disciplinary information, the correlation of all diagnostic findings, deduction of a definitive diagnosis and, finally, integration of all the above into a single multiparameter report. In this review, we summarise the contemporary approach to the biopsy, diagnosis and reporting of lymphoproliferative disorders.

Decision Trees↗

PubMed2005

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.

Basement Membrane↗

PubMed2005

Occurrence of c-kit+ tumor cells in hepatitis B virus-associated hepatocellular carcinoma.

Progenitor cells, termed oval cells, are involved in the pathogenesis of hepatocellular carcinoma (HCC) in animal models. By immunolabeling for c-kit and CD34 in human hepatitis B virus-associated cirrhosis with HCC (50 cases) and those with cirrhosis alone (10 cases), we found c-kit+ tumor cells in tumor tissue in 40 of 50 HCCs. The proportion was less than 0.1% of total tumor cell volume in most HCCs. Immunostaining for c-kit also was detected in sinusoidal endothelial cells in 43 of 50 HCCs. The incidence of oval cell occurrence in the adjacent nonneoplastic tissue in cases of HCC was high (44/50). The occurrence of oval cells, c-kit+ tumor cells, and c-kit+ sinusoidal cells in cases of human hepatitis B virus-associated HCC suggests that oval cell proliferation might be associated with the development of human hepatitis B virus-associated HCC. Furthermore, the c-kit+ sinusoidal cells might have a role in angiogenesis and progression of human hepatitis B virus-associated HCC.

Adult↗

PubMed2004

The role of molecular studies in lymphoma diagnosis: a review.

Lymphoma classification is based on a multiparametric approach to diagnosis, in which clinical features, morphology, immunophenotype, karyotype and molecular characteristics are important to varying degrees. While in most cases, a diagnosis can be confidently established on the basis of morphology and immunophenotype alone, a small proportion of diagnostically difficult cases will rely on molecular studies to enable a definitive diagnosis. This review discusses the various molecular techniques available including Southern blotting (SB), polymerase chain reaction (PCR), fluorescence in situ hybridisation (FISH)--including multicolour-FISH/spectral karyotyping and comparative genomic hybridisation--and also gene expression profiling using cDNA microarray technology. Emphasis is given to the analysis of antigen receptor gene rearrangements and chromosomal translocations as they relate to lymphoma diagnosis and also in the setting of minimal residual disease (MRD) detection and monitoring. Laboratories performing these tests need to have expertise in these areas of testing, and there is a need for greater standardisation of molecular tests. It is important to know the sensitivity and specificity of each test as well as its limitations and the pitfalls in the interpretation of results. Above all, results of molecular testing should never be considered in isolation, and must always be interpreted in the context of clinical and other laboratory data.

Blotting, Southern↗

PubMed2004

Incorporation of microwave tissue processing into a routine pathology laboratory: impact on turnaround times and laboratory work patterns.

AIMS: To examine the impact of microwave (MW) tissue processing on turnaround times (TATs) in a routine diagnostic laboratory. METHODS: A retrospective review of TATs for tissue processing (specimen receipt to completion of H&E-stained section) and pathologists' report generation (receipt of stained section to validation of completed report) for small biopsies processed in a MW-histoprocessor (Milestone RHS-2, Italy) was performed and compared with similar TATs for specimens processed conventionally prior to the introduction of MW histoprocessing. RESULTS AND CONCLUSIONS: The TAT for conventional tissue processing was almost 21 h compared with 6.5 h by MW-processing. Reporting TATs fell from 4.3 to 3.2 hours per case, respectively, largely because stained sections became available for reporting in the early afternoon instead of towards the end of the working day. If small biopsies are triaged and handled separately, the TATs can be further reduced, and in selected urgent cases, sections can be available for diagnosis within 90 minutes. The quality of MW processed sections was indistinguishable from those obtained with routine 4-hour processing. The drastic reduction in TATs signifies a new era in histopathological diagnosis in which the majority of reports can be generated within 24 hours of specimen receipt with attendant impact on patient management and hospitalisation costs.

Biopsy↗

PubMed2004

Ultra-rapid microwave-stimulated tissue processing with a modified protocol incorporating microwave fixation.

AIMS: To develop an ultra-rapid microwave (MW)-stimulated histoprocessing protocol that incorporates MW fixation and produces consistent, high quality sections. METHODS: A range of fresh autopsy tissues was divided into three groups composed of equal numbers of small and large tissue blocks. Group 1 tissues were fixed for 8 hours in 4% buffered formaldehyde and processed in a conventional tissue processor through a 15-hour cycle. Group 2 tissues were processed in a MW histoprocessor according to the manufacturer's recommended protocol of irradiation in a proprietary reagent before embedding in paraffin. Group 3 tissues were processed with our protocol that incorporated the addition of MW fixation in 4% buffered formaldehyde and MW irradiation in isopropyl alcohol after irradiation in the proprietary reagent. RESULTS: The manufacturer's protocol resulted in 'grey' and 'wet look' artefacts in large tissue blocks. These artefacts did not occur in our protocol which produced sections that were indistinguishable from those obtained with conventional 23-hour processing. Histochemical and immunohistochemical stains were also indistinguishable and the tissue blocks cut very smoothly. CONCLUSIONS: The incorporation of an additional step to ensure adequate tissue fixation and one to ensure optimal dehydration and clearing resulted in a MW histoprocessing protocol that produced consistent results for both large and small tissue blocks. Paraffin-impregnated blocks can be produced very rapidly from fresh small and large tissue blocks in 45 and 100 minutes, respectively.

Artifacts↗

PubMed2004

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.

Artifacts↗

PubMed2003

Digital imaging applications in anatomic pathology.

Digital imaging has progressed at a rapid rate and is likely to eventually replace chemical photography in most areas of professional and amateur digital image acquisition. In pathology, digital microscopy has implications beyond that of taking a photograph. The arguments for adopting this new medium are compelling, and given similar developments in other areas of pathology and radiologic imaging, acceptance of the digital medium should be viewed as a component of the technological evolution of the laboratory. A digital image may be stored, replicated, catalogued, employed for educational purposes, transmitted for further interpretation (telepathology), analyzed for salient features (medical vision/image analysis), or form part of a wider digital healthcare strategy. Despite advances in digital camera technology, good image acquisition still requires good microscope optics and the correct calibration of all system components, something which many neglect. The future of digital imaging in pathology is very promising and new applications in the fields of automated quantification and interpretation are likely to have profound long-term influence on the practice of anatomic pathology. This paper discusses the state of the art of digital imaging in anatomic pathology.

Education, Medical↗

PubMed2002

Prognostic relevance of immunohistochemically detected lymph node micrometastasis in patients with gastric carcinoma.

BACKGROUND: Micrometastases consisting of one to a few cells in lymph nodes resected during gastrectomy are difficult to identify using conventional hematoxylin and eosin (H&E) stains. It has been shown that immunostaining for cytokeratins is effective in detecting lymph node micrometastasis in a variety of human tumors, but only a few previous reports demonstrated its use in the treatment of patients with early and advanced gastric carcinoma, and those reports had conflicting results. METHODS: In this study, 3625 regional lymph nodes that were dissected in gastrectomy specimens from 153 patients with early-stage gastric carcinoma (46 patients) and advanced gastric carcinoma (107 patients) were immunostained with the anticytokeratin cocktail AE1/3 for micrometastasis (median, 23 lymph nodes; range, 8-66 lymph nodes). Micrometastasis (MM) was defined as a single tumor cell or clusters of tumor cells that were missed on conventional examination with H&E stains but were detected by immunostaining with broad-spectrum anticytokeratin antibodies. RESULTS: Lymph node metastasis (LNM) was detected in 609 lymph nodes (17%) by H&E staining. MM was identified in another 191 of the remaining lymph nodes (6.3%) from 75 patients. Twenty-eight of those patients were up-staged. There was a significant correlation between MM and depth of tumor invasion (P < 0.01). Patients with MM had a decreased 5-year survival rate (49%) compared with patients without MM (76%) for both early and advanced gastric carcinoma. The effect of MM on survival was most pronounced for patients in the Stage I and LNM negative group. CONCLUSIONS: Immunohistochemical examination using broad-spectrum anticytokeratin antibodies increased the detection rate of LNM and had a significant impact on staging and survival in patients with gastric carcinoma.

Adenocarcinoma↗

PubMed2002

Practical telepathology using a digital camera and the internet.

Digital camera technology has developed rapidly and a large choice of reasonably priced, user-oriented models are now available. These can be used for both macroscopic and microscopic photography with good resolution. Internet transmission of digital images also makes it possible to consult pathologists anywhere in the world. This study tests a simple, fast, and inexpensive method for practical transmission of images for diagnosis using a digital camera and the Internet. Using a commercial digital camera mounted with a phototube adapter to a light microscope (6 images per case on average), 2210 digital images (310 Mb) from 347 cases of gastrointestinal, lung, and uterus specimens were captured. Each image, stored in medium compression JPEG (Joint Photographers Experts Group) format with 1024 x 768 pixel resolution, required approximately 5 seconds to capture after the case had been reviewed and appropriate fields for imaging selected (30 seconds per case on average). The images were transmitted from Samsung Medical Center, Seoul, to Korea University Hospital, Seoul, and John Hunter Hospital, Newcastle, Australia. Transmission was 100% successful with a total upload time of 3 hours for 310 MB of data (31 seconds per case on average). The images were downloaded in 2 hours and viewed on a 17-inch color monitor with a maximal resolution of 1280 x 1024 pixels. Telepathology diagnoses were made with 95% and 97% concurrence by two pathologists at Korea University Hospital and John Hunter Hospital, respectively. We suggest that the current level of commercial technology yields fast, convenient and economical tools for practical telepathology diagnosis.

Humans↗

PubMed2002

Superheating antigen retrieval.

Heat-induced antigen retrieval in a variety of solutions has been shown to enhance the immunoreactivity of a wide range of antigens in routine formalin-fixed, paraffin-embedded tissues. Accurate time and temperature control is important for standardization and optimization of the procedure but is difficult to achieve. This study used a device to attain precise time and temperature control for antigen retrieval at 120 degrees C under 1.9 bar pressure. It compares the efficacy of this method with antigen retrieval in a conventional pressure cooker, by microwave heating at 98 degrees C, and ultrasound retrieval at 40 and 70 W for 40 and 100 seconds. Multitissue and multitumor blocks containing a spectrum of normal tissues and a variety of tumors, respectively, were used, and 42 routine diagnostic antibodies were applied with a standard peroxidase conjugated streptavidin technique. Sections in which antigen retrieval was not performed served as controls. The three heat-induced methods showed distinctly better immunostaining for all antigens compared with those obtained with ultrasound retrieval. The latter method did not produce consistent staining and intensity, and the extent of staining was only marginally better than sections not subjected to antigen retrieval. Superheating at 120 degrees C produced the best overall results with the exception of antibodies to cytokeratin clones Cam 5.2, AE1/3, and 34BE12 in which superheating resulted in slightly inferior immunostaining compared with heating in a pressure cooker and at 98 degrees C.

Antigens↗