B-CELL LYMPHOMA OF MUCOSA-ASSOCIATED LYMPHOID-TISSUE OF THE THYMUS - A REPORT OF 2 CASES WITH A BACKGROUND OF SJOGRENS-SYNDROME AND MONOCLONAL GAMMOPATHY

Two rare cases of low-grade B-cell lymphoma of mucosa-associated lymph oid tissue (MALT) arising in the thymus are reported. Both patients (a 61-year-old man and a 75-year-old woman) were suffering from Sjogren' s syndrome and immunoglobulin (Ig)A kappa monoclonal gammopathy. Mixed IS-A-IgG cryoglobulinemia was also present in the male case. Tumor ce lls expressed IgA and kappa antibody reactive proteins identical with serum IgA kappa M. Moreover, we could demonstrate rearrangements of th e immunoglobulin heavy and light chain genes, which supported the mono clonal origin of tumor cells. Immunological abnormalities improved aft er thymectomy in one case in which the tumor cells were confined to th e thymus, but not the other with regional lymph node involvement, sugg esting a causal role for the tumor. MALT lymphomas of the thymus thus appear to be associated with immunological disorders such as Sjogren's syndrome or monoclonal gammopathy. Copyright (C) 1998 by W.B. Saunder s Company.