B-cell lymphoma of the mucosa-associated lymphatic tissue (MALT) presenting with bone marrow and peripheral blood involvement.
A 46-year-old female patient was diagnosed as having a low-grade malignant B-cell lymphoma of the gastric MALT, stage IV, with bone marrow involvement and a leukaemic blood picture. Different from the infiltrate in the gastric mucosa, which consisted mainly of centrocyte-like cells, the leukaemic cells presented with a blood-picture resembling infectious mononucleosis but showing a predominance of plasma cells. Despite these cytological differences, a common clonal origin for both cellular compartments was demonstrated immunophenotypically and genotypically. Low-grade B-cell lymphomas of the MALT may thus initially present with stage IV disease and a leukaemic blood picture.