Basophilic chronic granulocytic leukaemia with hyperhistaminaemia.

Two patients with typical Philadelphia chromosome positive chronic granulocytic leukaemia (CGL) developed an accelerated phase of the disease characterized by an increase white blood cell count and marked basophilia in the bone marrow and peripheral blood. Histamine levels were extremely high in both patients. Hyperhistaminaemia was manifested as wheezing, urticaria, diarrhoea, and pruritus in one patient and as peptic ulcer disease and peripheral oedema in both patients. In one case, gastric acid studies revealed a very high basal to stimulated ratio (BAO/MAO). Treatment with the investigational agent metiamide, an H2 receptor histamine antagonist, resulted in marked improvement in symptoms and reduction in gastric acid output. Extreme basophilia in CGL may be associated with hyperhistaminaemia, and manifestations of both the H1 and H2 type may occur.