Leukemia, chronic granulocytic
Chronic granulocytic leukemia (CGL) is also known as chronic myelogenous (or myelocytic) leukemia. The disease is characterized by the abnormal overgrowth of granulocytic precursors (myeloblasts, promyelocytes,
metamyelocytes, and myelocytes) in bone marrow, peripheral blood, and body tissues.
metamyelocytes, and myelocytes) in bone marrow, peripheral blood, and body tissues.
CGL is most common in young and middle-aged adults and is slightly more common in men than in women; it’s rare in children. In the United States, 3,000 to 4,000 cases of CGL develop annually, accounting for roughly 20% of all leukemias.
The clinical course of CGL proceeds in two distinct phases: the insidious chronic phase, with anemia and bleeding abnormalities, and the acute phase (blastic crisis), in which myeloblasts, the most primitive granulocytic precursors, proliferate rapidly. This disease is invariably fatal. Average survival time is 3 to 4 years after onset of the chronic phase and 3 to 6 months after onset of the acute phase.
Causes
CGL’s exact cause is unknown. However, almost 90% of patients with CGL have the Philadelphia (Ph1) chromosome, an abnormality discovered in 1960 in which the long arm of chromosome 22 is translocated, usually to chromosome 9. Radiation and carcinogenic chemicals may cause this chromosome abnormality. Myeloproliferative diseases also seem to increase the incidence of CGL, and some physicians suspect that an unidentified virus causes this disease.
Signs and symptoms
Typically, CGL induces these signs and symptoms:
anemia (fatigue, weakness, decreased exercise tolerance, pallor, dyspnea, tachycardia, and headache)
thrombocytopenia, with resulting bleeding and clotting disorders (retinal hemorrhage, ecchymoses, hematuria, melena, bleeding gums, nosebleeds, and easy bruising)
hepatosplenomegaly, with abdominal discomfort and pain; splenic infarction from leukemic cell infiltration.
Other signs and symptoms include sternal and rib tenderness from leukemic infiltrations of the periosteum; low-grade fever; weight loss; anorexia; renal calculi or gouty arthritis from increased uric acid excretion; occasionally, prolonged infection and ankle edema; and, rarely, priapism and vascular insufficiency.
Diagnosis
In patients with typical signs and symptoms, chromosomal analysis of peripheral blood or bone marrow showing Ph1 and low leukocyte alkaline phosphatase levels confirms CGL. Other relevant laboratory results include:
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