Monoclonal immunoglobulin-secreting lymphoma in a patient with severe combined immunodeficiency disease.

A 3.5 year old boy with X-linked severe combined immunodeficiency disease (SCID), who had been in laminar flow isolation throughout his life, developed a B cell tumour producing up to 3008 mg/dl of an IgM kappa paraprotein 1 month after infusion of both liver and thymus cells from a fetal donor and 6 months after the last of six fetal liver cell infusions given over a 3 year period. Pretransplant studies revealed a high percentage of circulating B lymphocytes. HLA typing suggests that the tumour was of host origin.