Abstract
A female of 1 month old was admitted on November 19, 1984 to Tokushima University Hospital because of petechiae, papular eruption and hepato-splenomegalia. The leucocyte count of peripheral blood on admittion was 355×103/μl with 91% of blasts.
The diagnosis of acute monocytic leukemia was made from positive reaction of her leukemic cells for myeloperoxydase and α-naphtyle butylate esterase stain with NaF inhibition, and positive reaction of several monoclonal antibodies to monocyte antigen.
A initial combination chemotherapy, neo-mini COAAP, was started with slight effect. But, the second treatment with VP-16 was so effective that the patient got into partial remission.
But, spinal tap revealed the presence of CNS leukemia whose cells consisted of blasts and polymorphonuclear like cells in various differentiation stage, which were weakly positive for myeloperoxydase and positive for α-naphtyl butylate esterase stain. From these facts, it was suspected that monocytic leukemia cells which invaded into cerebro-spinal fluid developed lineage switch and maturation to polymorphonuclear like cells. This type of lineage switch and maturation from monoblast to polymorphonuclear like cell has not been known both clinically and experimentally.
