Hairy Cell Leukemia: Residual Splenic Disease After Successful α_2b-Interferon Therapy

Abstract

Splenectomy with liver biopsies were performed in six hairy cell leukemia patients in whom complete remission was documented after 12 months of α_2b-interferon (α_2b-IFN) daily administration. Interferon was discontinued the day before splenectomy. The average spleen weight was 383 g, with evidence of red pulp infiltration by hairy cells in all patients with a parallel reconstitution of the white pulp. On splenic imprint preparations mononuclear cells, with features of hairy cells, were identifiable in every case. Study of frozen splenic sections by the alkaline anti-alkaline phosphatase immunohistochemical method revealed a strong HC2 antibody positivity in the red pulp, confirming the hairy cell nature of the red pulp mononuclear infiltration. In addition on imprint preparation acid phosphatase resistant to tartrate (TRAP) positive cells were easily found in all cases. No liver hairy cell infiltration could be found. One month after splenectomy their hematological counts were corrected to absolute normal values. No significant changes of the serum soluble interleukin-2 receptor levels were observed after splenectomy when compared with the presplenectomy levels. At eighteen months postsplenectomy, five patients are still in remission, while the sixth relapsed six months postsplenectomy. We conclude from our study that i) complete remission could not be confirmed after splenectomy in our patients, ii) the criteria of complete remission in HCL should be reassessed and iii) splenectomy was beneficial for most of our patients.

Key Words:

• Hairy cell leukemia
• residual splenic HCL
• α2b Interferon