A series of 36 human thymomas have been immunohistochemically analyzed using a panel of antibodies recognizing B-cell markers including CD20. Most thymomas exhibiting the cortical pattern, according to the criteria of Marino and Muller-Hermelink, were characterized by areas of medullary differentiation containing variable numbers of CD20+ B lymphocytes, thus mimicking the medulla of normal thymus. On the other hand, B cells were absent or rare in thymomas recognized as mixed using the same morphological criteria. Surprisingly, we observed in most mixed thymomas variable numbers of CD20+ spindle cells, characterized by long slender processes. Using double-marker analysis we could demonstrate the epithelial nature of these cells (expression of keratin and lack of lymphoid and B-cell-related markers). The immunoreactivity of thymoma epithelial cells with L26, an antibody widely used in the characterization of B-cell lymphomas, can represent a drawback of practical relevance in the differential diagnosis of mediastinal tumors.

Neoplastic epithelial cells in a subset of human thymomas express the B cell-associated CD20 antigen

Facchetti, F;
1992-01-01

Abstract

A series of 36 human thymomas have been immunohistochemically analyzed using a panel of antibodies recognizing B-cell markers including CD20. Most thymomas exhibiting the cortical pattern, according to the criteria of Marino and Muller-Hermelink, were characterized by areas of medullary differentiation containing variable numbers of CD20+ B lymphocytes, thus mimicking the medulla of normal thymus. On the other hand, B cells were absent or rare in thymomas recognized as mixed using the same morphological criteria. Surprisingly, we observed in most mixed thymomas variable numbers of CD20+ spindle cells, characterized by long slender processes. Using double-marker analysis we could demonstrate the epithelial nature of these cells (expression of keratin and lack of lymphoid and B-cell-related markers). The immunoreactivity of thymoma epithelial cells with L26, an antibody widely used in the characterization of B-cell lymphomas, can represent a drawback of practical relevance in the differential diagnosis of mediastinal tumors.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11379/501093
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