The paper describes a case of a patient with refractory hairy cell leukemia. In 
spite of the absence of CD25 expression, the disease was classified as a 
classical form according to the WHO classification (2008), as also confirmed by 
the detection of BRAFV600E mutation. The disease was characterized by resistance 
to all lines of therapy (interferon-a, splenectomy, cladribin). Clinical and 
hematological remission was achieved within 2 months of administration of the 
BRAF kinase inhibitor vemurafenib.