[A new case of acute lymphoblastic leukemia with Philadelphia chromosome in the child (author's transl)].

The systematic study of the medullary karyotype in the course of haemopathies has led us to a new case of Philadelphia chromosome in an acute lymphoblastic leukemia. This was a case of a 13 year old child. Is this a particular class of haemopathy? Do such observations put a question on the dual theory of the origins of blood germ cells? The elaborate medullary karyotype in the course of haemopathy may solve this problem. A rigorously nosological classification is essential for appraising the therapeutic plan chosen and making a pronosis.