Leukopenic Myelosis: (Section of Medicine).

The term "leukopenic myelosis" is used to describe a type of "myeloblastic leukaemia" in which the leukocyte content of the peripheral blood is subnormal for the whole or the greater part of the course of the disease. Separation from the frankly leukaemic cases is made only on the grounds of clinico-haematological convenience.Twenty-two cases have been seen in the past four years. The age-incidence varied from 3-73 years; 10 were in males and 12 in females. Acute, subacute, and chronic types may be recognized. In all the main characteristic is a progressive anaemia; in acute cases haemorrhagic phenomena and necrotic angina are common.The blood-count is characterized by orthochromic or hyperchromic anaemia, sometimes with reticulocytosis and erythroblastosis. Leukopenia may persist throughout the course, or a terminal leukaemia may occur-especially in the chronic cases. The features of the differential count are the presence of myeloblasts-although the percentage may be below 5%-and the hiatus leukaemicus. Thrombocytopenia usually means a rapid course.This clinico-haematological picture may be mimicked more or less closely by pernicious anaemia, aplastic anaemia, agranulocytosis, and the leuko-erythroblastic anaemias. The sternal puncture findings are, however, diagnostic, and show a great preponderance of primitive myeloid cells, most frequently with a predomincnce of myeloblasts. In two cases evidence was found that the erythropoietic tissues shared in the hyperplasia.