Response to splenectomy in 65 patients with hairy cell leukemia: an evaluation of spleen weight and bone marrow involvement.

Sixty-five patients with hairy cell leukemia underwent splenectomy; 27 had a complete remission as defined by a return in WBC, RBC, and platelet counts to a defined level, and 38 had a partial remission with a return of only one or two of these parameters to the defined level. The 5-yr actuarial survival for all patients is 68%; for CR patients it is 76%, and for PR patients 62%. The response to splenectomy did not correlate with the spleen weight. Seventeen patients had a postsplenectomy platelet count of less than 200 x 10(9)/liter, and 34 patients had a postsplenectomy platelet count of 200 x 10(9)/liter or greater. A presplenectomy bone core biopsy hairy cell index (HCI) was calculated by multiplying the percent marrow cellularity by the percent of hairy cells in the marrow for 51 patients. The difference in the mean HCI between the two platelet response groups is statistically significant (p less than 0.05). Of the 15 patients with a presplenectomy HCI of 0.7 or greater, 9 (60%) did not have a satisfactory platelet response to splenectomy, whereas of 36 patients with an HCI of 0.7 or less, only 8(22%) did not have a satisfactory platelet response to splenectomy (p less than 0.01). The HCI appears to indicate the significance of underproduction of platelets as a result of marrow replacement by hairy cells.