Hairy cell leukemia. What is new forty years after the first description?

Hairy cell leukemia represent 2% of all the leukemias. The etiology is unknown. The diagnosis is based on the peripheral blood examination, showing characteristic lymphoid B cells, with loose lacy chromatin and unconstant cytoplasmic projections. The abnormal lymphoid cells express CD19, CD20, CD22, CD79a, CD25 and CD103. The tumor cells are Sig + with clonal light chain restriction. The treatment is based on recombinant IFN: we discuss the interest and the risks of second malignancy related to the prescription of the purine analogues.