CD200 Expression in Neuroendocrine Neoplasms.

Objectives: CD200 expression has been well studied in hematopoietic malignancies; however, CD200 expression has not been well-characterized in neuroendocrine neoplasms. We examined CD200 expression in 391 neuroendocrine neoplasms from various anatomic sites.

Methods: Tissue blocks containing pulmonary small cell carcinoma, pulmonary carcinoid, large cell neuroendocrine carcinoma, pancreatic neuroendocrine tumor, gastrointestinal carcinoid, and Merkel cell carcinoma were evaluated for CD200 expression by immunohistochemistry.

Flow cytometric analysis of CD200 expression by pulmonary small cell carcinoma.

Background: CD200 is a membrane bound glycoprotein that is expressed by a variety of normal tissues and hematopoietic malignancies. Flow cytometric analysis of CD200 expression has utility in the evaluation of mature B-cell neoplasms, myeloma, and acute leukemia; however, CD200 expression in nonhematopoietic malignancies has not been extensively studied.

Methods: We studied 14 cases of biopsy proven pulmonary small cell carcinoma in which a discrete CD45 negative, CD56 positive abnormal cell population was identified by flow cytometry.

Marked Variability in Reported Minimal Residual Disease Lower Level of Detection of 4 Hematolymphoid Neoplasms: A Survey of Participants in the College of American Pathologists Flow Cytometry Proficiency Testing Program.

Context: Flow cytometry is often applied to minimal residual disease (MRD) testing in hematolymphoid neoplasia. Because flow-based MRD tests are developed in the laboratory, testing methodologies and lower levels of detection (LODs) are laboratory dependent.

Objectives: To broadly survey flow cytometry laboratories about MRD testing in laboratories, if performed, including indications and reported LODs.

Primary Rosai-Dorfman disease of the bone in a patient with history of breast cancer: appearance on 99mTc-MDP scintigraphy, CT, and X-ray.

A 49-year-old woman with history of breast cancer presented with pain at the level of the left anterior proximal tibia. An x-ray of the tibia demonstrated a lytic cortical lesion that prompted a whole-body 99mTc-MDP bone scan. The bone scan revealed intense bone remodeling at the level of the tibial lytic lesion and in the cervical spine.

Determining true HER2 gene status in breast cancers with polysomy by using alternative chromosome 17 reference genes: implications for anti-HER2 targeted therapy.

Purpose: The ratio of human epidermal growth factor receptor 2 (HER2) to CEP17 by fluorescent in situ hybridization (FISH) with the centromeric probe CEP17 is used to determine HER2 gene status in breast cancer. Increases in CEP17 copy number have been interpreted as representing polysomy 17. However, pangenomic studies have demonstrated that polysomy 17 is rare.

High concordance between immunohistochemistry and fluorescence in situ hybridization testing for HER2 status in breast cancer requires a normalized IHC scoring system.

The American Society of Clinical Oncologists and College of American Pathologists have recently released new guidelines for laboratory testing of HER2 status in breast cancer, which require high levels (95%) of concordance between immunohistochemistry positive (3+) and fluorescence in situ hybridization-amplified cases, and between immunohistochemistry negative (0/1+) and fluorescence in situ hybridization-nonamplified cases; these required levels of concordance are significantly higher than those found in most published studies. We tested the hypothesis that a modification of the HER2 immunohistochemistry scoring system could significantly improve immunohistochemistry and fluorescence in situ hybridization concordance. A total of 6604 breast cancer specimens were evaluated for HER2 status by both immunohistochemistry and fluorescence in situ hybridization using standard methodologies.

2006 Bethesda International Consensus recommendations on the immunophenotypic analysis of hematolymphoid neoplasia by flow cytometry: optimal reagents and reporting for the flow cytometric diagnosis of hematopoietic neoplasia.

Immunophenotyping by flow cytometry has become standard practice in the evaluation and monitoring of patients with hematopoietic neoplasia. However, despite its widespread use, considerable variability continues to exist in the reagents used for evaluation and the format in which results are reported. As part of the 2006 Bethesda Consensus conference, a committee was formed to attempt to define a consensus set of reagents suitable for general use in the diagnosis and monitoring of hematopoietic neoplasms.

Identification and purification of classical Hodgkin cells from lymph nodes by flow cytometry and flow cytometric cell sorting.

We demonstrate the feasibility of using flow cytometry (FC) to identify the Hodgkin and Reed-Sternberg (HRS) cells of classical Hodgkin lymphoma (CHL). Initial flow cytometric studies of the HRS cell line L1236 demonstrated potentially useful antigens for identifying HRS cells. L1236 cells spontaneously bound normal T cells, analogous to the T-cell rosetting of HRS cells seen in tissue sections of CHL, but these interactions could be blocked by using a cocktail of unlabeled antibodies to 4 adhesion molecules.

Evaluation of 12 antibodies for distinguishing epithelioid mesothelioma from adenocarcinoma: identification of a three-antibody immunohistochemical panel with maximal sensitivity and specificity.

We evaluated the sensitivity and specificity of 10 monoclonal and two polyclonal antibodies for distinguishing epithelioid mesothelioma from adenocarcinoma (AdCA) using immunohistochemistry (IHC). The antibodies were directed against the mesothelial-associated antigens mesothelin, calretinin, cytokeratin 5, thrombomodulin, Wilms' tumor-1 (WT-1) gene product and HBME-1, and the nonmesothelial antigens Lewis-Y blood group (antibody BG8), MOC-31, BerEp4, CD15, and carcinoembryonic antigen (CEA) family. The 133 tumors evaluated included 65 malignant epithelioid mesotheliomas, 22 lung AdCAs, 27 ovarian serous carcinomas, 24 breast carcinomas, and five gastric carcinomas.

Four-color flow cytometry shows strong concordance with bone marrow morphology and cytogenetics in the evaluation for myelodysplasia.

The ability of 4-color flow cytometry (FC) to help identify myelodysplastic syndromes (MDSs) was evaluated in 124 bone marrow aspirates from unselected patients with unexplained cytopenias and/or monocytosis. The morphologic features of bone marrow aspirate smears were correlated with FC and cytogenetic findings blindly, and patterns of antigen expression were compared with patterns seen in nonneoplastic and normal marrow specimens. Of 124 cases, 58 (46.

Escape from therapy-induced accelerated cellular senescence in p53-null lung cancer cells and in human lung cancers.

Accelerated cellular senescence (ACS) has been described for tumor cells treated with chemotherapy and radiation. Following exposure to genotoxins, tumor cells undergo terminal growth arrest and adopt morphologic and marker features suggestive of cellular senescence. ACS is elicited by a variety of chemotherapeutic agents in the p53-null, p16-deficient human non-small cell H1299 carcinoma cells.

Intravascular large B-cell lymphoma involving hemangiomas: an unusual presentation of a rare neoplasm.

We report the clinicopathological features of two cases of intravascular large B-cell lymphoma involving cutaneous hemangiomas. The cases were identified from the consultation files of two of the authors. Both patients were women, 64 and 55 years of age, who presented with long-standing cutaneous hemangiomas of the posterior scalp and left shoulder, respectively.

Bronchial-associated lymphoid tissue lymphoma: a clinical study of a rare disease.

Bronchial-associated lymphoid tissue (BALT) lymphoma is a distinct subgroup of low-grade B-cell extranodal non-Hodgkin's lymphoma, classified as marginal-zone lymphoma. This study was performed in order to assess the natural history of this rare entity. We evaluated retrospectively the clinical data of 22 patients with biopsy-proven BALT lymphoma at two tertiary-care institutions from 1996 to 2002.

Prominent clonal B-cell populations identified by flow cytometry in histologically reactive lymphoid proliferations.

We describe 6 cases from the University of Washington Hematopathology Laboratory (Seattle) in which prominent, clonal, follicle center B-cell populations were identified by flow cytometry and confirmed by molecular methods, but in which the histologic features showed reactive follicular hyperplasia without evidence of bcl-2 overexpression or the t(14;18). The 6 cases included 5 lymph node biopsy specimens and 1 tonsillectomy specimen. Of the 6 cases, 5 occurred in young males (8-28 years) with no known immunologic abnormality; the other case was a 32-year-old, HIV-positive woman.

Novel FLT3 point mutations within exon 14 found in patients with acute myeloid leukaemia.

Internal tandem duplications in FLT3 are the most common mutation in acute myeloid leukaemia (AML), with agarose gel electrophoresis of polymerase chain reaction products (PCR/agarose) being the screening method of choice for these mutations. As PCR/agarose screening does not detect small mutations, single-stranded conformational polymorphism analyses (PCR/SSCP) were used in an attempt to identify previously unrecognized point mutations in FLT3 exons 14 and 15 of 140 AML patients, using newly designed primers that anneal within intron sequences. Novel missense point mutations were found in exon 14, suggesting additional investigations should be performed in AML and other haematopoietic malignancies, using this sensitive technique.

Four-color flow cytometry identifies virtually all cytogenetically abnormal bone marrow samples in the workup of non-CML myeloproliferative disorders.

Because of the relative insensitivity of conventional cytogenetics for identifying abnormalities in the non-chronic myelogenous leukemia (CML) myeloproliferative disorders (MPDs), we directly compared the abilities of flow cytometry and cytogenetics to identify such cases. We retrospectively identified 66 patients whose bone marrow samples were evaluated for abnormalities of myeloid antigen expression by 4-color flow cytometry as part of the workup to rule out a non-CML MPD. The patients all had concurrent cytogenetic evaluation of the marrow and no evidence of the t(9;22).

CTL are inactivated by herpes simplex virus-infected cells expressing a viral protein kinase.

Numerous cell-to-cell signals tightly regulate CTL function. Human fibroblasts infected with HSV type 1 or 2 can generate such a signal and inactivate human CTL. Inactivated CTL lose their ability to release cytotoxic granules and synthesize cytokines when triggered through the TCR.

Using 4-color flow cytometry to identify abnormal myeloid populations.

Context: The diagnosis of myeloproliferative disorders (MPDs) and myelodysplastic syndromes (MDSs) has historically relied on combining clinical information with the morphologic features of the peripheral blood and bone marrow to reach a final diagnosis. Objective evidence of a myeloid stem cell neoplasm in the form of a clonal cytogenetic abnormality is provided in only 30% to 40% of the non-chronic myeloid leukemia (CML) chronic MPDs (non-CML MPDs) and in a similar percentage of the MDSs.

Objective: To identify normal patterns of antigen expression during myeloid maturation and to determine whether flow cytometric evaluation of myeloid maturation represents an additional objective way to assess the likelihood of a stem cell neoplasm.

Lineage-specific identification of nonhematopoietic neoplasms by flow cytometry.

To extend flow cytometry (FC) to the diagnosis of nonhematopoietic neoplasms, we have developed new flow cytometric assays to identify expression of cytokeratin, epithelial cell adhesion molecule (EpCAM)/epithelial glycoprotein-2, myogenin, and CD99. To validate these assays, we correlated the flow cytometric results with the histologic and immunohistochemical results on paraffin-embedded tissue in a series of 21 cases, including 17 carcinomas, 1 atypical carcinoid, 2 rhabdomyosarcomas, and 1 Ewing sarcoma/primitive neuroectodermal tumor (ES/PNET). Six of 7 assayed carcinomas and the carcinoid were positive for cytoplasmic cytokeratin by the flow cytometric assay.