HCL cells show strong acid phosphatase reaction which is resistant to tartaric acid. HCL-V. Spleen histology shows expansion and infiltration of the red pulp with naked white pulp. Treatment Interferon alpha produces good partial responses in HCL but invariably the disease relapses. HCL-V is not responsive to the above treatments with only half achieving transient partial responses to the purine analogs with splenectomy being the best palliative therapeutic measure. Evolution HCL and HCL-V are characterised by a chronic clinical course with the symptoms deriving from cytopenias, and abdominal distension due to splenomegaly.
Few patients undergo transformation.
HCL -V has a poorer prognosis and in the only largest series reported the median survival is 9 years. Several reports describe nonclonal or oligoclonal abnormalities in HCL and in some with clonal abnormalities translocations involving the 14q32.3 the site of the IGH locus, rearrangements of 14q22-24 and abnormalities of chromosomes 11 and 12 have been described. HCL-V is often characterised by a complex karyotype. Genes involved and Proteins Note Molecular studies suggest that hairy cells have aberrations in the constant region of the IgM intron which could be responsible for errors in class switching and explain the pattern of Ig heavy chain expression in HCL which does not fit the the class switching model which occurs in normal B-cell differentiation. Colocalisation of pp52 with F-actin occurs at the base of the villi.