Example of a complete remission obtained with vemurafenib in relapsed/refractory HCL. The BM biopsies of a patient with multiple HCL relapses is shown (A) before and (B) after 8 weeks of treatment with vemurafenib. H&E (top panels) and CD20 (red; bottom panels) stainings show a massive leukemic infiltration which is largely cleared by vemurafenib (<10% residual HCL cells posttherapy). Pictures of immunohistochemical stainings were taken with the 40×/0.85 objective (U Plan Apo) of a BX61 microscope equipped with a DP71 digital camera, using cell^B x.y acquisition software (all from Olympus).