Clinical and immunologic spectrum of plasmacytoid lymphocytic lymphoma without serum monoclonal IgM.

As first suggested by Lukes & Collins (1975), and recently confirmed in the literature, the pathological lesion associated with Waldenström's macroglobulinaemia can be found in patients with serum IgG or IgA monoclonal proteins. To expand upon the clinical and immunologic spectrum of this lesion, we reviewed the records of 12 patients with identical tumour morphology, though lacking an IgM paraprotein. The median age of the patients was 62 years. In five patients the tumour secreted monoclonal IgG, while one secreted monoclonal IgA. One patient had normal serum protein electrophoresis, although monoclonal light chains were demonstrated on urinary protein electrophoresis. The remaining patients had no detectable monoclonal protein. Marker studies demonstrated the B cell origin of tumour, these findings were consistent with the monoclonal protein secreted. Clinically, these cases varied, from peripheral blood involvement resembling chronic lymphocytic leukaemia, to typical lymphomatous processes, to presentations resembling multiple myeloma, reflecting the similarity of all of these conditions as varying expressions of neoplasia of the B cell system.