Thrombocytosis in Chronic Granulocytic Leukemia: Incidence and Clinical Significance

The clinical significance of an elevated platelet count in the course of chronic granulocytic leukemia was studied in a group of 111 previously untreated patients, whose entire course was evaluated by one clinic. Seventy-one patients (64%) developed a platelet count >450,000/cu mm either at diagnosis (56 patients) or in the subsequent course (15 patients). Twenty-nine of the 71 patients had counts in excess of 1 x 10⁶/cu mm. Four patients had serious thrombohemorrhagic complications. None were fatal, and all occurred in the group with counts over a 1 x 10⁶/cu mm. The occurrence of thrombocytosis as a new observation in the face of previous normal counts (15 patients) was associated with frank blastic crisis (six cases) or heralded its onset with a median duration of 8 mo (nine cases). Thrombocytosis per se was associated with a shorter survival (median 36 mo) as opposed to 45 mo in the group (40 cases) whose count was never elevated.