Typical hairy-cell leukaemia with IgGk paraproteinaemia

A case of hairy-cell leukaemia (HCL) with IgG(k) paraprotein is described. The typical clinico-pathological features of the patient are stressed, and it is shown that the hairy cells (HCs) were producing and secreting IgGk. The case is placed in a more general context by the demonstration that HCs from other typical cases of HCL produce and secrete IgG. These findings conclusively demonstrate that HCL is a B-cell disease.