Acute lymphoblastic crisis in a patient with chronic lymphatic leukemia

A case of chronic lymphatic leukemia terminating in a lymphoblastic crisis is described. The small lymphocytes were demonstrated to be B cells, they carried immunoglobulins on their surface and formed EAC rosettes. The lymphoblasts had no immunoglobulins on their surface and only 18% of them formed EAC rosettes, none formed E rosettes. The lymphoblasts could be either immature B cells or Null cells.