Hairy cell leukaemia (HCL) is an uncommon, chronic B cell leukaemia, first reported as a distinct entity in the 1950s.,听听HCL accounts for 2% of lymphoid leukaemias, with a male predominance and median age at diagnosis of 58听years. Classical HCL and its variant form (HCL鈥怴) are now regarded as separate entities,听with different cytological, haematological and immunophenotypic features.听BRAF听V600E mutation, present in virtually 100% of cases of classical HCL,听is regarded as a disease鈥恉efining event, and is absent in HCL鈥怴.
Advances in management of classical HCL, from use of interferon in the 1980s, to purine analogues in the 1990s, monoclonal antibodies in the 2000s and BRAF inhibitors in the current decade, have resulted in excellent prognosis, with the majority of patients achieving long鈥恖asting remissions and prolonged survival.,听听There remains no clear optimal treatment for HCL鈥怴, which is one鈥恡enth as common as classical HCL, with a 5听year survival rate of 57%.听Advances in diagnostics and treatment necessitate an update of the 2012 BSH guidelines.
Declaration of Interests
The BSH paid the expenses incurred during the writing of this guidance. None of the authors had conflicts of interest to declare. All authors have made a declaration of interests to the BSH and Task Force Chairs which may be viewed on request.