CLINICAL MANIFESTATIONS

In most cases CML is a biphasic or triphasic disease. The initial
chronic phase may last several years without change, but ultimately it
either changes abruptly to an acute phase or, more commonly, evolves
slowly into a phase of "acceleration," which later progresses to the
acute phase. The acute phase is usually defined by the observation of
>30% blasts or blasts plus promyelocytes in the blood or marrow,57 but
criteria for defining the accelerated phase are imprecise.58 A
reasonable classification has been proposed by the International Bone
Marrow Transplant Registry (Table 73-2).

Table 73-2. Criteria Established by the International Bone Marrow
Transplant Registry for Classifying the Phases of CML

1).   Chronic phase

No significant symptoms (after treatment);

None of the features of accelerated phase or blastic phase.

2).  Accelerated phase

WBC count difficult to control with conventional use of busulfan or
hydroxy-

urea in terms of doses required or shortening of intervals between
courses Rapid doubling of WBC count t<5 days) =-:10% blasts in blood or
marrow 2:20% blasts plus promyelocytes in blood or marrow a:20%
basophils plus eosinophils in blood Anemia or thrombocytopenia
unresponsive to busulfan or hydroxyurea Persisent thrombocytosis

Additional chromosome changes (evolving new clone) Increasing
splenomegaly Development of chloromas or myelofibrosis

Blastic phase

2:30% blasts plus promyelocytes in the blood or bone marrow

(Data from International Bone Marrow Transplant Registry.)