THE MULTIFACE MORPHOLOGY OF ACUTE-LEUKEMIA

Three distinct morphological phases during the course of acute leukemi a in a 16 year old girl are described. The patient presented with morp hology of acute lymphoblastic leukemia, relapsed with acute myeloblast ic leukemia which later on evolved to monoblastic phase. This clinical , morphological and ultrastructural observation provides clinical evid ence supporting the current concept of normal and leukemic haematopoie sis, as well as clonal evolution, according to which a stem cell is ca pable of giving rise to different haematopoietic lineages. It is conce ivable that chemotherapy altered the balance between the stem cells an d the bone marrow microenvironmental stromal cells, resulting in clona l evolution or release of a new subclone with the disease relapse.