Blast Crisis

Definition

Blast crisis is the aggressive and rapidly fatal terminal phase of BCR-ABL1 positive Chronic Myeloid Leukemia (CML). This phase of the disease is characterized by accumulation of immature myeloblasts or lymphoblasts similar to those found in patients with acute leukemia.

Characteristics

Clinical Features

When left untreated, CML is a biphasic disease. Patients typically present in a relatively benign chronic phase which is characterized by symptoms of fatigue and lethargy, bleeding, moderate weight loss, an enlarged palpable spleen, and a high white blood cell (WBC) count. The increased WBC population in large part constitutes cells of the myeloid compartment, with over-representation of the granulocyte series. Within a period of 3–5 years, the natural course of the disease is to accelerate, then to transform to an aggressive and rapidly terminal acute phase or blast crisis of 4–6 months duration. Features associated with this transformation include an