Bone marrow trephines. Findings in patients with hairy cell leukaemia before and after treatment.

Bone marrow trephine biopsies from 20 patients with hairy cell leukaemia were reviewed at diagnosis and during therapy with alpha-interferon (IFN) and with 2-chlorodeoxyadenosine (2-CdA). At time of diagnosis the trephines revealed classical features of hairy cell leukaemia and profound alterations of haematopoiesis. All three lines showed dysplastic features with architectural, qualitative and quantitative changes. Review of consecutive trephine biopsies in patients that received IFN showed that a complete remission with disappearance of the tumour was never achieved and that the dysplastic features persisted. An improvement of haematopoiesis was noted, but recovery, especially of the myelopoiesis, was never completely achieved. By contrast, patients treated with 2-CdA de novo and previously treated with IFN achieved a complete remission in all but three cases. The trephine biopsies showed an improvement of haematopoiesis with progressive disappearance of the dysplastic features and a good recovery of myelopoiesis. A residual lymphocytosis was present, but as it was also present in age-matched control cases it could not be considered as a residual tumour. The disappearance of the leukaemic infiltrate probably constitutes a prerequisite for the recovery and normalization of haematopoiesis, while the dysplastic changes present at diagnosis could be the result of cytokine production by the leukaemic cells.