[Follicular dendritic cells in extranodal non-Hodgkin's lymphomas]

Extranodal lymphomas of the thyroid (n = 19), kidney (n = 15) and testis (n = 30) were investigated histologically and immunohistochemically using the monoclonal antibody Ki-FDC1P, which recognizes follicular dendritic cells on paraffin sections. Only lymphomas of the thyroid were of MALT-lymphoma type and contained tumor associated abortive follicles of follicular dendritic cells. In kidney and testis, no MALT-Lymphomas were found. Lymphoepithelial lesions, a hallmark of MALT-Lymphomas, occurred not only in thyroid MALT-lymphomas, but also in testicular centroblastic lymphomas (lacking other features of MALT-lymphomas). Therefore, lymphoepithelial lesions are not specific for MALT-lymphomas.