Hairy cell leukaemia. A clinico-pathologic study of 16 patients.

The clinical and histological features of 16 cases of hairy cell leukaemia are described. The disease mainly affected middle aged and old men. All patients had clinically detected splenomegaly and more than half the patients had "dry" bone marrow aspirations. Most of the patients had pancytopenia but one patient had leucocytosis. The spleen was usually markedly enlarged; the mean weight of the excised spleens was 1700 g. The histological findings were typical. In the bone marrow there was monotonous proliferation of small mononuclear cells combined with an increase in reticulin. In the spleen numerous similar cells were seen in the red pulp with almost total replacement of the white pulp. Tumour cell infiltrates were also seen in the liver where they mainly involved the sinusoids, and in the lymph nodes where they caused partial obliteration of the lymph node structures. Four patients died of causes related to hairy cell leukaemia during the follow-up period. The immediate cause of death was infection in every case. Three of these patients had received chemotherapy as opposed to 3 of the 12 patients who did not die of hairy cell leukaemia.