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.
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.
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.
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.
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:
❑ white blood cell abnormalities: leukocytosis (leukocyte count ranging from 50,000/µl to 250,000/µl), occasional leukopenia (leukocyte count less than 5,000/µl), neutropenia (neutrophil count less than 1,500/µl) despite a high leukocyte count, and increased circulating myeloblasts
❑ hemoglobin level: commonly below 10 g/dl
❑ hematocrit: low (less than 30%)
❑ platelet count: thrombocytosis (more than 1 million/µl) common
❑ serum uric acid level: possibly more than 8 mg/dl
❑ bone marrow aspirate or biopsy: hypercellular, characteristically shows bone marrow infiltration by significantly increased number of myeloid elements (a biopsy is done only if aspirate is dry); in the acute phase, myeloblasts predominate
❑ computed tomography scan: may identify the organs affected by leukemia.
Aggressive chemotherapy has so far failed to produce remission in patients with CGL. Consequently, the goal of treatment in the chronic phase is to control leukocytosis and thrombocytosis. The most commonly used oral drugs are busulfan and hydroxyurea. Aspirin is commonly given to prevent stroke if the patient’s platelet count exceeds 1 million/µl.
Ancillary CGL treatments include:
❑ local splenic radiation or splenectomy to increase platelet count and decrease adverse effects related to splenomegaly
❑ leukapheresis (selective leukocyte removal) to reduce leukocyte count
❑ allopurinol to prevent secondary hyperuricemia or colchicine to relieve gout due to elevated serum uric acid levels
❑ prompt treatment of infections that may result from chemotherapyinduced bone marrow suppression.
During the acute phase of CGL, lymphoblastic or myeloblastic leukemia may develop. Treatment is similar to that for acute lymphoblastic leukemia. Remission, if achieved, is commonly short lived. Bone marrow or stem cell transplantation may help in certain phases of CGL. Despite vigorous treatment, CGL usually progresses after the onset of the acute phase.
For more information on treatment during the acute phase, see “Leukemia, acute,” page 484.
❑ In the patient with CGL, meticulous supportive care, psychological support, and careful patient teaching help make the most of remissions and minimize complications. (For more patient-teaching information, see Managing chronic granulocytic leukemia.)
❑ Reinforce the explanation of the disease and its treatment to the patient and his family.
Throughout the chronic phase of CGL when the patient is hospitalized:
❑ If the patient has persistent anemia, schedule laboratory tests and physical care with frequent rest periods in between, and assist the patient with walking if necessary.
❑ Regularly check the patient’s skin and mucous membranes for pallor, petechiae, and bruising.
❑ To minimize bleeding, suggest a soft-bristled toothbrush, an electric razor, and other safety precautions.
❑ To minimize the abdominal discomfort of splenomegaly, provide small, frequent meals. For the same reason, prevent constipation with a stool softener or laxative as needed. Ask the dietary department to provide a high-bulk diet, and maintain adequate fluid intake.
❑ To prevent atelectasis, stress the need for coughing and deep-breathing exercises.
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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
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Title: Handbook of Diseases Authors: Springhouse Publisher: Lippincott Williams & Wilkins Copyright: 2003 ISBN: 1-58255-266-5 
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