Leukemia, Chronic Granulocytic
Also called chronic myelogenous (or myelocytic) leukemia, chronic granulocytic leukemia is characterized by the abnormal overgrowth of granulocytic precursors (including myeloblasts, promyelocytes, metamyelocytes, and myelocytes) in bone marrow, peripheral blood, and body tissues.
The disease is most common in young and middle-aged adults, slightly more common in males than in females, and rare in children. In the United States, between 3,000 and 4,000 cases of chronic granulocytic leukemia develop annually, accounting for about 20% of all leukemias.
The clinical course of chronic granulocytic leukemia proceeds in two distinct phases: the insidious chronic phase, characterized by anemia and bleeding abnormalities, and eventually the acute phase (blast crisis), in which myeloblasts, the most primitive granulocytic precursors, proliferate rapidly. The disease is always
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.
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
Although the exact causes remain unknown, almost 90% of patients with this leukemia have the Philadelphia chromosome, an abnormality in which the long arm of chromosome 22 translocates to chromosome 9. Radiation and carcinogenic chemicals may induce this abnormality.
Myeloproliferative diseases also may increase the incidence of chronic granulocytic leukemia. Some researchers suspect that an unidentified virus causes this leukemia.
Complications
Complications include infection, hemorrhage, and pain.
Assessment
The patient history may reveal renal calculi or gouty arthritis (from increased uric acid excretion). The patient may relate symptoms of anemia: fatigue, weakness, dyspnea, decreased exercise tolerance, and headache. Evidence of bleeding and clotting disorders may include bleeding gums, nosebleeds, easy bruising, and hematuria. Additionally, the patient may report recent weight loss and anorexia.
The patient’s vital signs may include a low-grade fever and tachycardia. Inspection may reveal pallor and difficulty breathing, and ophthalmoscopic examination may disclose retinal hemorrhage.
Palpation may uncover hepatosplenomegaly with abdominal discomfort and pain (in splenic infarction from leukemic cell infiltration) and sternal and rib tenderness (from leukemic infiltration of the periosteum).
Auscultation may disclose hypoventilation, especially if the patient has dyspnea.
Diagnostic tests
Chromosomal studies of peripheral blood or bone marrow showing the Philadelphia chromosome and low leukocyte alkaline phosphatase levels confirm chronic granulocytic leukemia.
Serum uric acid level may exceed 8 mg/dl. (For other results obtained in a complete blood count (CBC), see CBC findings in chronic granulocytic leukemia.)
Bone marrow aspirate—or biopsy (performed only if the aspirate is dry)—may be hypercellular, showing bone marrow infiltration by a significantly increased number of myeloid elements; in the acute phase, myeloblasts predominate.
Computed tomography scan may identify the organs affected by this leukemia.
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