B-cells in thymic epithelial tumours. An immunohistochemical analysis of intra- and extraepithelial B-cell compartments.
A total of 26 thymomas and thymic carcinomas were studied by immunohistochemistry to determine the presence and distribution of intratumoural B-cells. Double staining experiments revealed two distinct B-cell populations in the thymic epithelial tumours. One was found within the perivascular space (PVS), which is separated from the neoplastic epithelium by a basement membrane. In all tumours the PVS contained lymphocytes with the immunophenotype of peripheral B-cells. Large numbers of B-cells with germinal centre formation were found almost exclusively in myasthenia gravis (MG)-associated tumours, mainly in cortical thymomas and well differentiated thymic carcinomas. A second population of B-cells was located in the neoplastic epithelial meshwork, mostly in areas of organoid medullary differentiation characterized by epidermoid cells or Hassall's corpuscules. This population frequently comprised large, CD23+ cells with dendritic features resembling the special type of intramedullary B-cells of the normal human thymus. In contrast, B-cells were uncommon in areas of mixed thymoma showing spindle celled medullary differentiation, and were almost completely absent from tumour areas composed of cortical type epithelium. Hence a medullary microenvironment with epidermoid cells corresponding to Hassall's corpuscules seems to be necessary for specific intrathymic B-cell homing.
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Institute of Pathology, Innsbruck University, Austria.
Kirchner
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Marx
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Müller-Hermelink
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HK
D000328:Adult; D000368:Aged; D015703:Antigens, CD / Q000032:analysis; D018941:Antigens, CD19; D000944:Antigens, Differentiation, B-Lymphocyte / Q000032:analysis; D001402:B-Lymphocytes / Q000276:immunology / Q000473:pathology*; D002277:Carcinoma / Q000473:pathology*; D015815:Cell Adhesion Molecules; D002454:Cell Differentiation; D004848:Epithelium / Q000473:pathology; D005260:Female; D006801:Humans; D007124:Immunoenzyme Techniques; D007072:Immunoglobulin D / Q000032:analysis; D007075:Immunoglobulin M / Q000032:analysis; D007150:Immunohistochemistry; D016130:Immunophenotyping; D037102:Lectins; D008297:Male; D008875:Middle Aged; D017455:Receptors, IgE / Q000032:analysis; D051918:Sialic Acid Binding Ig-like Lectin 2; D013945:Thymoma / Q000473:pathology*; D013953:Thymus Neoplasms / Q000473:pathology*
D015703:Antigens, CD; D018941:Antigens, CD19; D000944:Antigens, Differentiation, B-Lymphocyte; C497867:CD22 protein, human; D015815:Cell Adhesion Molecules; D007072:Immunoglobulin D; D007075:Immunoglobulin M; D037102:Lectins; D017455:Receptors, IgE; D051918:Sialic Acid Binding Ig-like Lectin 2