Decrease of Bone Marrow Fibrosis in Hairy Cell Leukemia (HCL) after 2-CdA Therapy.

Different degree of bone marrow fibrosis is commonly described in patients with HCL. Hairy cells produce and assemble an insoluble matrix of fibronectin, which is responsible for the bone marrow fibrosis. Production of fibronectin is related to activity of the disease. The aim of our study was to evaluate the change of bone marrow fibrosis before and after 2-CdA therapy.

Patients and methods: 18 patients, who were treated with 2-CdA and achieved complete remission in 6 months, were included in this analyses. Trephin bone marrow biopsy were obtained before therapy and after therapy in 12 and 24 moths. The 3μm thick section were stained with Gomori reticulin stain. Grading of reticulin fibrosis (scale of 0 to IV): grade 0 - reticulin fibers (RF) absent, grade I - scattered RF or foci of fine reticular network (RN), grade II - diffuse fine RN, grade III - diffuse fine RN and scattered thick fibers, grade IV - diffuse thick reticular fibers and presence of collagen fibers.

Results: Before 2-CdA therapy: reticulin fibrosis was grade 0 in 0 p., I in 3p., II in 4p, III in 11p., IV in 0p.. Decrease of reticulin fibrosis in 12 months after 2-CdA was demonstrated in 51% of patients (grade 0 in 1, I in 8p., II in 5p., III in 4p., IV in 0p.), in 24 moths 77% of patients (grade 0 in 2, I in 10p., II in 4p., III in 2p., IV in 0p). Bone marrow fibrosis was increased by one grade in 3p. in 24 months after therapy.

Conclusion: Successful 2-CdA therapy in patient with 2-CdA leads to significant reduction of bone marrow fibrosis.