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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Using cell size, cell density, and microscopic growth pattern, 20 duodenal stromal tumors were initially separated into benign and malignant categories. The 10 histologic benign tumors had uniform spindle cells, low cellularity, and an organoid pattern. All had round eosinophilic collagen blobs scattered among the spindle cells, were 4.5 cm or less in maximum diameter, and had two or fewer mitoses per 50 high-power fields (HPF). None metastasized or recurred during a median follow-up of 7 years. In contrast, the 10 histologically malignant tumors were highly cellular, all had two or more mitoses per 50 HPF, and all but one had diameters of 4.5 cm or greater, the exception being 4 cm. Eight cases also had benign-appearing areas, usually submucosal. Eight patients died with disease a median of 31 months after resection, almost all with liver metastases. One patient is alive with metastasis at 13 years. The patient with the 4-cm malignant tumor is disease free at 49 months. All 15 cases were strongly vimentin positive, 11 had S-100 protein, and seven had the CD34 marker. None were desmin or actin positive. No immunophenotype separated benign from malignant. The proliferation marker, proliferating cell nuclear antigen, correlated with histologic diagnosis and clinical outcome, but Ki-67 did not. Based on light microscopic features alone, benign and malignant duodenal stromal tumors can be separated from each other. Tumors with large cells and an organoid pattern are predictably benign; in this study, these tumors measured 4.5 cm or less in diameter and had fewer than 2 mitoses per 50 HPF. Highly cellular tumors with small cells and little or no organoid pattern are malignant. They usually have a diameter greater than 4.5 cm and more than two mitoses per 50 HPF, and they are usually fatal. Immunostaining for cytoplasmic proteins and proliferation markers offers no additional prognostic information to the light microscopic appearances. These conclusions apply only to duodenal tumors; whether they also apply to stromal tumors of the jejunum and ileum is not known.
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PMID:Stromal tumors of the duodenum. A histologic and immunohistochemical study of 20 cases. 752 72

The term "gastrointestinal stromal tumor" (GIST) has been applied to mesenchymal tumors that represent neither typical leiomyomas nor schwannomas. In this study we analyzed immunohistochemically 67 histologically benign [< 2 mitoses/10 high-power field (HPF)], six borderline (3-5 mitoses/10 HPF), and 23 malignant GIST (> 5 mitoses/10 HPF) and compared them with 10 typical leiomyomas and 5 schwannomas of the gastrointestinal tract. The benign GISTs with spindle cell pattern (67 cases) were typically negative for muscle cell markers (only 3% positive for desmin and 25% for alpha-smooth muscle actin) and S100 protein, but 70% of the cases were positive for CD34, the myeloid progenitor cell antigen also present in endothelial cells and some fibroblasts. However, none of the cases was positive for CD31 (PECAM-1), a more endothelial cell-specific antigen. The absence of CD31 in GIST separates it from Kaposi's sarcoma, a tumor known to be positive for both CD34 and CD31. Fourteen cases of benign GIST of epithelioid cell type showed an immunophenotypic profile similar to the spindle cell tumors. The small intestinal tumors were more commonly actin positive and less commonly CD34 positive than were the gastric tumors. The malignant spindle and epithelioid GIST showed features essentially similar to those in corresponding benign tumors. In contrast, all typical leiomyomas were positive for muscle cell markers and were negative for CD34 and S100 protein. Gastrointestinal schwannomas were S100-protein positive, and negative for muscle markers and CD34. Our results show that gastrointestinal mesenchymal tumors can be immunophenotypically divided in categories that correlate with light microscopically defined diagnostic entities, namely typical leiomyomas, schwannomas, and GIST, most cases of the latter representing tumors of primitive mesenchymal cells that are CD34 positive.
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PMID:Gastrointestinal stromal tumors--value of CD34 antigen in their identification and separation from true leiomyomas and schwannomas. 753 Apr 9

CD34 is a sialylated transmembrane glycoprotein of unknown function that is present in myeloid progenitor cells, endothelial cells, and some fibroblast-related mesenchymal cells. However, its tissue distribution is still incompletely characterized. In this study we evaluated the distribution of CD34 antigen in tumors of the central and peripheral nervous system. For comparison the tumors were also stained for CD31, also known as platelet-endothelium cell adhesion molecule (PECAM-1), a transmembrane glycoprotein so far considered to be endothelium specific beyond its reactivity with certain hematopoietic cells. Neurofibromas showed consistently high numbers of CD34-positive spindle cells, whereas peripheral and acoustic schwannomas were negative. A subset of meningiomas (15%) showed CD34-positive tumor cells, and some were also weakly positive for CD31. Gliomas were negative. Meningeal hemangiopericytomas were consistently CD34 positive, but CD31 negative. These results indicate a moderately widespread distribution of the CD34 antigen in nervous system tumors, and necessitate caution in making conclusions regarding endothelial cell differentiation of nervous system tumors on the basis of CD34 immunoreactivity.
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PMID:CD34 immunoreactivity in nervous system tumors. 753 84

We have previously demonstrated that the immunoglobulin (Ig) heavy chain variable region (VH) sequences expressed by the malignant clone in multiple myeloma (MM) contain a high degree of somatic mutation without clonal diversity. This sequence can be used to identify all members of the malignant clone in this B cell malignancy. We sequenced the variable regions expressed by patients with MM and generated primers from the complementarity determining region (CDR) sequences specific for each patient's tumor. Using these primers, we performed PCR amplification on highly purified subpopulations of cells separated by expression of CD10, CD34 and CD38. The results of these experiments demonstrate: 1) there is a small fraction of CD10-expressing tumor cells in MM patients, 2) CD34-bearing malignant cells do not exist in MM, and 3) although the vast amount of tumor is in the CD38-expressing cells, a small amount of tumor is in the CD38-negative population. We also used these primers to determine whether pre-class switch (i.e., Cmu-expressing lymphocytes) clonal cells exist in these patients. After PCR amplification with CDR1 and Cmu primers, colony hybridization was performed using both framework 3 (FR3) and CDR3 probes. Out of > 200 FR3-hybridizing colonies, < or = 5 colonies also hybridized with the CDR3 probe. Colonies which hybridized with both these probes were sequenced, and none of these sequences matched even closely the CDR3 expressed by the malignant clone. These results make the existence of a pre-class switch malignant cell unlikely in MM. Overall, these results suggest that the malignant clone in MM derives from a cell late in B lymphocyte development.
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PMID:Multiple myeloma clones are derived from a cell late in B lymphoid development. 753 71

Purification of human hematopoietic stem cells (HSC) may be useful clinically for preparation of tumor-free grafts to be used for autologous transplantation and as targets for gene therapy. To analyze the phenotype of the human HSC, assays were used that measure the unique properties of stem cells, i.e., their long-term repopulating ability and their multilineage potential. These assays include: (1) an in vitro long-term hematopoietic culture system, using the murine bone marrow stromal cell line SyS1, which supports both B lymphopoiesis and myelopoiesis; (2) fetal human bone grafts implanted in SCID-hu mice, in which maintenance of CD34+ cells and B and myeloid differentiative capacity of candidate stem cell populations may be measured; (3) fetal human thymus grafts in SCID-hu mice, which allow the analysis of in vivo T-cell potential of a candidate stem cell population. Stem cells in adult bone marrow (ABM) or cytokine-mobilized peripheral blood (MPB) are thought to express CD34 but lack expression of markers indicating lineage commitment. This CD34+ Lineage- (Lin-) subpopulation has been isolated by fluorescence-activated cell sorting and tested for activity in the assays described here. CD34+ Lin- cells from both ABM and MPB demonstrated long-term engraftment in the SCID-hu bone model. This CD34+ Lin- population can be subfractionated further using an antibody to Thy-1. The Thy-1+ subset of CD34+Lin- cells is enriched for both long-term culture-initiating cells (LTC-1C) and has the ability to engraft in vivo.
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PMID:Analysis of human hematopoietic stem cell populations. 753 40

A major potential problem of autologous transplantation in the treatment of advanced malignancy is the infusion of tumor cells. A multi-institutional study of purified CD34-selected peripheral blood progenitor cell (PBPC) transplantation was conducted in 37 patients with advanced multiple myeloma receiving myeloablative chemotherapy. Fourteen days after intermediate-dose cyclophosphamide, prednisone, and granulocyte colony-stimulating factor (G-CSF), a median of 3 (range, 2 to 5) 10-L leukaphereses yielded 9.8 x 10(8)/kg (range, 3.7 to 28.3) mononuclear cells. The adsorbed (column-bound) fraction contained 5.9 x 10(6) cells/kg (range, 1.6 to 25.5) with 4.65 x 10(6) CD34 cells/kg (range, 1.2 to 23.3). Using Poisson distribution analysis of positive polymerase chain reactions with patient-specific complementarity-determining region 1 (CDR1) and CDR3 Ig-gene primers, tumor was detected in leukapheresis products from 8 to 14 unselected patients and ranged from 1.13 x 10(4) to 2.14 x 10(6) malignant cells/kg. After CD34 selection, residual tumor was detected in only three patients' products. Overall, a greater than 2.7- to 4.5-log reduction in contaminating multiple myeloma cells was achieved. CD34 PBPCs were infused 1 day after busulfan (14 mg/kg) and cyclophosphamide (120 mg/kg), and granulocyte-macrophage colony-stimulating factor was used until hematologic recovery. The median time to both neutrophil and platelet recovery was 12 days (range, 11 to 16 days and 9 to 52 days, respectively). The median number of erythrocyte and platelet transfusions was 7 (range, 2 to 37) and 3 (range, 0 to 85), respectively. Patients receiving fewer than 2 x 10(6) CD34 cells/kg had significantly prolonged neutropenia, thrombocytopenia, and an increased red blood cell and platelet transfusion requirement. Thus, CD34 selection of PBPCs markedly reduces tumor contamination in multiple myeloma and provides effective hematopoietic support for patients receiving myeloablative therapy.
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PMID:Transplantation of CD34+ peripheral blood progenitor cells after high-dose chemotherapy for patients with advanced multiple myeloma. 754 Aug 88

High spontaneous proliferation of acute myeloid leukemia (AML) in vitro is an unfavorable, tumor-specific prognostic factor. We investigated the frequency of drug-resistant tumor cells with high proliferating capacity in de novo AML and analyzed the expression of multiple resistance parameters in relation to the response to chemotherapy and overall survival. Thirty-eight patients were included in this study. P-glycoprotein (P-gp) expression was found in 28/38 patients and was associated with lower intracellular accumulation of DNR (P = 0.0001). Thirty-five out of 38 patients were treated with 1-2 regimens of daunorubicin (DNR)/cytarabine (Ara-C), and 57% attained a complete remission (CR). Failure to achieve a CR correlated with autonomous growth (P = 0.0064), CD34 and P-gp expression alone (P = 0.0005 and P = 0.048 respectively), and with simultaneous expression of P-gp and CD34 (P = 0.0001), but not with expression of the non-P-gp drug resistance associated-protein (p110), the multidrug resistance-associated protein (MRP), Ara-CTP formation or Ara-C incorporation, respectively. AML cells with CD34/P-gp double expression were more frequently observed in samples with high autonomous growth (P = 0.003). The median survival was 6 months in CD34+/P-gp+ patients as compared with 15 months in other AML patients (P = 0.003). In patients with de novo AML who fail on chemotherapy, a population of autonomously proliferating, immature AML cells with a multidrug resistant phenotype can be recognized. These cells thus show primary resistance to chemotherapy and have the potential for rapid regrowth, leading to resistant disease.
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PMID:Multidrug resistant cells with high proliferative capacity determine response to therapy in acute myeloid leukemia. 754 Oct 95

Tumor angiogenesis has been found to have prognostic significance in many tumor types for predicting an increased risk of metastasis. We assessed tumor vascularity in 43 cases of advanced stage (International Federation of Gynecologists and Obstetricians stages III and IV) ovarian cancer by using the highly specific endothelial cell marker CD34. Microvessel counts and stage were associated with disease-free survival and with overall survival by Kaplan-Meier analysis. The plots show that higher stage, higher average vessel count at 200x (200x avg) and 400x (400x avg) magnification and highest vessel count at 400x (400x high) magnification confer a worse prognosis for disease-free survival. Average vessel count of less than 16 (400x avg, P2 = 0.01) and less than 45 (200x avg, P2 = 0.026) suggested a better survival. Similarly, a high vessel count of less than 20 (400x high, P2 = 0.019) conferred a better survival as well. The plots suggest that higher stage, higher average vessel count at 200x and 400x, and highest vessel count at 200x and 400x show a trend to worse overall survival as well. With the Cox proportional hazards model, stage was the best predictor of overall survival, however, the average microvessel count at 400x was found to be the best predictor of disease-free survival. These results suggest that analysis of neovascularization in advanced stage ovarian cancer may be a useful prognostic factor.
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PMID:Tumor angiogenesis in advanced stage ovarian carcinoma. 754 13

Tumour cells from a patient with recurrent testicular germ cell cancer and bone marrow infiltration were found to express CD33 and CD34 in the absence of other haemopoiesis-associated antigens. After myelosuppression and treatment with G-CSF for stem cell mobilization, CD34-positive tumour cells were detected in the peripheral blood in addition to normal haemopoietic progenitor cells. The tumour cells were decreased in the leukapheresis product. Retrospectively, the appearance of tumour cells in the peripheral blood after stem cell mobilization was the first indication of impending relapse.
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PMID:Mobilization of CD34-positive tumour cells in a patient with testicular mixed germ cell tumour. 754 27

The immunophenotype of spindle cells in epidemic, endemic, and classic (sporadic) Kaposi's sarcoma (KS) lesions was defined by the demonstration of various cell markers and compared with that of KS-derived cell lines. No significant histological or immunophenotypic differences were observed between the three clinical types of KS at comparable stages. The spindle-cell compartment of the different KS types was composed predominantly of a mixture of proliferating CD45+/CD68+ bone-marrow-derived monocytes and TE7+/collagen+ fibroblastic cells with varying expression of EN4/PAL-E/CD31/CD34/CD36 endothelial-associated antigens and/or smooth-muscle-specific alpha-actin (alpha-actin). The latter cells appeared to represent transitional forms of fibroendothelial and fibromyocytic cells. The in vitro cultured KS-derived cell lines (KS-3, KS-6, and KS-8) expressed the fibroblastic antigen TE7 and smooth-muscle-specific alpha-actin but not leukocytic or endothelial-associated antigens consistent with the phenotype of fibromyoid spindle cells of primary lesions. Neither HIV antigen nor provirus DNA was demonstrable in the epidemic KS lesions. The observed heterogeneity of the spindle-cell compartment further substantiates the view that Kaposi's sarcoma, irrespective of clinical setting, expresses salient features more compatible with reactive, tumor-like lesion than clonal sarcoma.
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PMID:Heterogeneity of spindle cells in Kaposi's sarcoma: comparison of cells in lesions and in culture. 755 91


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