Characteristics and Treatment of Hairy Cell Leukaemia

Hairy cell leukaemia (HCL) is a rare chronic indolent lymphoproliferative disease of B-lymphocytes. It always infiltrates the spleen, bone marrow or other organs and is also present in the peripheral blood in more than 95% of cases. The disease takes its name from its characteristic wrinkled surface with hair-like projections. The prognosis of this infaust diagnosis has dramatically changed since the 1980s through more precise diagnosis and efective treatment with purine analogues (1984, 2-deoxycoformy-cine (2-dCF); 1990, 2-chlorodeoxyadenosine (2-CdA)). In our group of 38 patients, we confrmed the diagnostic possibilities and their accuracy; in addition to morphological examination, these include fow cytometric detection of typical surface CD antigens and immunohistochemical recognition of hairy cells in the trephine biopsy. The treatment percentage in the number of response rates (RRs) (100%), complete remissions (CRs) (79%) and overall survival of patients is comparable with previously known data. Overall survival rate without symptoms of disease for more than 10 years after treatment is 87% (33/38). The presence and quantity of minimal residual disease (MRD) after frst-line treatment in bone marrow determine subsequent progression or relapse of the disease, sometimes even occurring many years after the treatment. Probably some new pharmacotherapeutical possibilities (monoclonal antibodies, immunotoxins, tyrosine kinase inhibitors or inhibitors of B-Raf enzyme) could demonstrate the ability to eliminate MRD and cure it in relapsed patients or patients refractory to purine analogues. HCL has become an oncological disease with a relatively good prognosis and long-term survival after standard treatment with purine analogues despite the persistence of indolent MRD in the bone marrow at varying degree of residual infiltration intensity.