The above case illustrates an example of EMZL/MALT-type with initial pleural presentation. The distinction between this form of low-grade lymphoma and LPL cannot be made purely on the morphologic and immunohistochemical characteristics of the tumor cells; clinical extent of disease is also necessary for correct classification. Both are small B-cell proliferations with a similar immunohistochemical profile. Although plasma-cell or and/or plasmacytoid differentiation is invariably present in LPL, certain cases of EMZL/MALT-type also share this feature. LPL is characterized by infiltration of the bone marrow, lymph nodes, and spleen, all of which were uninvolved in our patient, with an associated serum monoclonal protein in the majority of cases.5In contrast, EMZL/MALT-type primarily involves and/or is first diagnosed in extranodal tissues. It is also increasingly recognized as a cause of Waldenstrom macroglobulinemia,6 a syndrome characterized by serum monoclonal gammopathy, usually of IgM type, in the setting of a neoplasm of small B-lymphocytes, plasmacytoid lymphocytes, and plasma cells.5 In consideration of the clinical context, the diagnosis of EMZL/MALT-type is therefore appropriate in this case, although one must acknowledge that the IgM monoclonality of the plasma cell component may have led other pathologists, on strictly morphologic and immunohistochemical grounds, to favor LPL.