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Query: UMLS:C0026764 (multiple myeloma)
 36,148 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In most instances, fusion of differentiated cell types with fibroblasts has resulted in the extinction of the differentiation-specific traits of the non-fibroblast parental cell. To explore the genetic basis of this phenomenon, we have studied a series of somatic cell hybrids between mouse myeloma and fibroblasts. All the hybrids were adherent having a fibroblast-like phenotype. Molecular analysis revealed that plasma cell specific genes like the productively rearranged Ig genes, the J chain gene and genes for the cell surface markers CD20 and PC1, were extinguished in the hybrids. In contrast, fibroblast specific genes like fibronectin, alpha 2(I) and III collagens, as well as the receptor for fibroblast growth factor (flg), were expressed. Extinction was not due to chromosomal loss or lack of the relevant genes. To learn about the mechanism(s) of this phenomenon we have looked for the presence of positive and negative transcription factors in our hybrids. Expression of the PU.1 transcription factor, a member of the Ets transcription factor family normally expressed in B cells and macrophages, was lost in the cell hybrids. Interestingly, we found that the B-cell-specific Oct-2 transcription factor was still expressed at somewhat variable levels in several of the hybrid cell lines. In contrast, expression of the recently identified octamer coactivator BOB.1/OBF.1 was extinguished in all cell hybrids. This supports a critical role of this transcriptional coactivator for B-cell-specific gene expression. In addition, the Id and HLH462 genes coding for proteins known to repress bHLH transcription factors by formation of heterodimers, were found to be expressed at increased levels in fibroblasts and in the hybrids, indicating that their increased levels might also contribute to the suppression of myeloma-specific genes. Our results show that in myeloma x fibroblast hybrids, the phenotype of the fibroblast is dominant. It is suggested that fibroblasts contain regulatory "master" genes that are responsible for activation of the fibroblast differentiation pathway and suppress differentiation programs of other cell types.
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PMID:Coordinate suppression of myeloma-specific genes and expression of fibroblast-specific genes in myeloma X fibroblast somatic cell hybrids. 864 90

Plasmablastic lymphoma (PBL) is an uncommon aggressive lymphoma arising most frequently in the oral cavity of HIV-infected patients. Rare cases of PBL have been reported in extraoral sites, particularly extranodal sites, as well as in immunocompetent patients. We report an unusual case of PBL in a 69-year-old, HIV-negative non-immunocompromised man presenting with generalized lymphadenopathy. To our knowledge, this is the first case of PBL presented as primarily generalized lymphadenopathy in HIV-negative patients. Histologic examinations of cervical, inguinal and axillary lymph nodes demonstrated a neoplastic proliferation of large cells with extensive necrosis. The neoplastic cells formed sheets with a relatively cohesive growth pattern interspersed by small lymphocytes and plasma cells. The large tumor cells expressed MUM1, OCT-2 and BOB.1, and were negative for CD138, CD38, AE1/AE3, melan A, PLAP, S100, vimentin, CD117, CD30, ALK-1, leukocyte common antigen (CD45), T-cell, B-cell and histolytic markers, CD56, CD10 and BCL-6. The proliferation index by Ki-67 immunohistochemistry was approaching 100%. In situ hybridization for Epstein-Barr Virus-encoded RNA (EBER) was positive in large malignant cells. A diagnosis of PBL was made. These findings indicate that PBL should be included in the differential diagnosis of an HIV-negative, immunocompetent patient with generalized lymphadenopathy. The adjacent plasma cells were positive for CD138 and CD38 and show kappa-light chain restriction, but without EBER expression, raising the possibility of a preexisting or concurrent plasmacytoma and that the PBL may be a high-grade transformation from a preexisting plasma cell neoplasm following Epstein-Barr virus infection. Electron microscopy showed numerous circumferential long slender peripheral cytoplasmic projections in the large tumor cells, suggesting that some of the previously reported large B-cell lymphoma with cytoplasmic projections may actually be PBL.
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PMID:Plasmablastic lymphoma may occur as a high-grade transformation from plasmacytoma. 2096 60

In some instances, the overlap in morphologic features and antigen expression between nodular lymphocyte predominant Hodgkin lymphoma (NLPHL) and classical Hodgkin lymphoma (cHL) can cause confusion in the diagnosis. In these cases, the transcription factors (TFs) B-cell specific activator protein (BSAP)/Pax-5, octamer binding protein-2 (Oct-2), B-lymphocyte-specific co-activator BOB.1/OBF.1, Bcl-6 protein and multiple myeloma-1/interferon regulatory factor-4 (MUM1/IRF-4) may aid in clarifying the diagnosis. Twenty-two cases of NLPHL were studied for the immunohistochemical expression of Pax-5, Oct-2, BOB.1, Bcl-6 protein and MUM1/IRF-4. Our results sustain the usefulness of the selected set of TFs to diagnose and distinguish NLPHL from cHL since Pax-5, Oct-2, BOB.1 and Bcl-6 are consistently expressed by lymphocyte predominant (LP) cells and reported by others to be often unexpressed in Hodgkin and Reed-Sternberg cells. By contrast, MUM1/IRF-4 protein scored negative in the majority of LP cells, but is reported to be expressed in almost all cases of cHL. Thus, although the expression of transcription factors is very heterogeneous, their simultaneous implementation for positive and differential diagnosis may be useful.
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PMID:B-cell transcription factors Pax-5, Oct-2, BOB.1, Bcl-6, and MUM1 are useful markers for the diagnosis of nodular lymphocyte predominant Hodgkin lymphoma. 2142 34

Nodular lymphocyte predominant Hodgkin lymphoma (NLPHL) is an uncommon variant of classical Hodgkin lymphoma. It is characterized histologically by presence of lymphohistiocytic cells which have B-cell phenotype, are positive for CD19, CD20, CD45, CD79a, BOB.1, Oct.2, and negative for CD15 and CD30. Patients often present with early stage of disease and do not have classical B symptoms. The clinical behavior appears to mimic that of an indolent non-Hodgkin lymphoma more than that of classical Hodgkin disease. The purpose of the present report is to define the biology of NLPHL, review its clinical presentation, and summarize the available clinical data regarding treatment.
Clin Lymphoma Myeloma Leuk 2014 Aug
PMID:Nodular lymphocyte predominant hodgkin lymphoma: biology, diagnosis and treatment. 2465 Sep 75