Erythropoiesis in hairy cell leukaemia: a true erythroid failure.

A quantitative evaluation of erythropoiesis was carried out in 12 patients with hairy cell leukaemia (HCL). The results were compared with those obtained in eight patients with aplastic anaemia (AA) in order to define the characteristics of erythroid failure in HCL. Discriminant analysis was applied to both haematological and erythrokinetic parameters of the two disease groups. Plasma iron concentration and MCV were significantly higher in AA, and allowed a perfect separation of the patients. As regards erythrokinetics, values of ineffective erythropoiesis and peripheral haemolysis were able to separate completely the two disease groups, being significantly lower in HCL than in AA. A true erythroid failure was the peculiar erythrokinetic pattern of HCL. This conclusion allows one to speculate on the nature of the stem cell damage in this disease.