Knowledge of leucosis in children and infants is of relatively recent origin. According to Adler, from the discovery of leucosis in 1545 until 1914 only seventeen cases in infants were reported and of these ten have been accepted. Ramsay in 1927 published an analysis of one hundred cases of leucosis in children, ninety one from the literature and nine from hospital records in Glasgow. Two years later Warren presented a review of the literature on acute leucosis. His conclusions were based on one hundred and thirteen cases on which autopsied had been performed, eighty five from the literature and twenty eight new cases. Of these one hundred and thirteen cases twenty seven were under the age of ten years. Since that time the literature has been increasing steadily but in the British periodicals there have been few contributions to the subject. Gittens analysis of fourteen cases was published in 1933. All of these cases were studied carefully both clinically and haematologically and had autopsies performed. They form a noteworthy contribution. He remarks on the surprisingly few papers that have been written on leucosis, in children. As recently as 1940 Piney in his article which included two cases of myeloblastic leucosis in children states that acute leucosis is so protean a disease and possibly so common a one that every case should be recorded in order to enable proper clinical pictures to be put together.

Leucosis was first described by Hughes Bennett of Edinburgh in 1845. He described the enlarged spleen and called attention to the large number of leucocytes in the blood. He named the condition leukocythaemia. In the same year Virchow described this disease and called it leukaemia. He differentiated between a splenic leukaemia in which the principle pathological change was in the spleen and a lymphatic leukaemia in which the lymph glands were primarily involved. In 1857 Von Friedrich described the first case of acute leucosis. In 1891 Ehrlich published his work on differential stains for granular and non- granular leucocytes and made it possible to separate cases where the cells are mainly granular or myeloid from cases where the cells are chiefly non -granular or lymphocytes. Further progress has been made since then and the differentiation is more accurate so that we are now able to recognize what is known as monocytic leucosis.

The purpose of this paper is to present the findings of cases of leucosis observed in the Edinburgh Royal Hospital for Sick Children during the past twenty years. This hospital cared for practically all children requiring hospitalisation in the city of Edinburgh and district. The population of this area is approximately half to three quarters of a million people. Of the thirty cases included twenty had autopsies performed. The clinical records were in varying degree of completeness. Some cases died so rapidly that full investigations were not possible. The post mortem examinations were all performed by the pathology department and the majority by the same pathologist.

In addition to the above thirty cases there were seven more which were indexed as leucosis. Two of these records were missing. The other five cases, including two cases with post mortem, were inconclusive either due to the difficult clinical and pathological picture or due to insufficient clinical and haematological investigations.