Circulating buttock cells in non-Hodgkin's lymphoma.

Leukemic B cells with a characteristically sharp nuclear cleft seemingly dividing the nucleus into two or more parts have been entitled "buttock cells" and are subject of this study. These cells were found in leukemic non-Hodgkin's lymphomas (NHL) and usually have been related to follicular center cell lymphomas. However, buttock cells also closely resemble cells present in intermediate lymphocytic lymphoma (ILL) and mantle zone cells of reactive lymphoid tissues. Ultrastructurally, it became apparent that the separate nuclear lobes of buttock cells were connected by chromatin bridges. Immunophenotypically, circulating buttock cells had a variable phenotype, which may indicate either a follicle center or mantle zone origin. The use of CD5 and FMC7 monoclonal antibodies might be of discriminative help. These leukemic NHL have to be differentiated from classical chronic lymphocytic leukemia (CLL) with help of cytomorphology and immunophenotyping, since the former usually have a worse prognosis and generally will require a different treatment.