Further Outpatient Care
Hairy cell leukemia is usually indolent and protracted; late relapses occur. Long-term outpatient follow-up is often necessary in most patients.
Evaluation of minimal residual disease by posttreatment bone marrow biopsies using anti-CD20 by flow cytometry reveals that 13-51% of patients in apparent CR had minimal residual disease and appears to predict clinical relapse. Because a majority respond very well to retreatment (92% response) or salvage treatment (80% response), no evidence supports treatment of minimal residual disease.
Newer therapies, such as anti-CD20 monoclonal antibody rituximab, had been tested in patients with hairy cell leukemia that was refractory to standard treatment. Several studies with small numbers of patients who received rituximab showed an overall response of 64%, with a median duration of response of 14 months, to 100% response and a duration of 73 months, indicating that this form of therapy is active against hairy cell leukemia.
Further Inpatient Care
Hyperuricemia may occur during therapy in patients with hairy cell leukemia with leukocytosis and high tumor burden. Add allopurinol at 300 mg per day orally.
The risk of second malignancies has been observed in affected patients either through hairy cell leukemia disease itself or secondary from the immunosuppressive effects of the therapy, including melanoma, prostate cancers, gastrointestinal malignancies, non-Hodgkin lymphomas, and nonmelanomatous cancers.
A 20-year follow-up in 117 patients in British Columbia showed that 31% developed a second malignancy, of which 30% were diagnosed before hairy cell leukemia was found. [29] On the other hand, MD Anderson reported no excess of second malignancies among 350 patients with hairy cell leukemia who were treated with interferon, 2'-CdA, or 2'-DCF. [30]
Prognosis
Hairy cell leukemia behaves like a chronic leukemia. With new therapies, most patients achieve clinical remissions and, sometimes, long-term cures. For example, the overall survival rate with 2'DCF up front or after alpha interferon failure in 241 patients was 80-85% at 10 years. Although relapses are known to occur after 5-10 years, they are usually responsive to the same treatment.
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Blood film at × 400 magnification. This image demonstrates a lymphocytosis and an absence of any other type of blood cell (pancytopenia). The characteristic cytoplasmic projections are already visible. Photographed by U. Woermann, MD, Division of Instructional Media, Institute for Medical Education, University of Bern, Switzerland.
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Blood film at × 1000 magnification. This image demonstrates lymphocytes with characteristic cytoplasmic projections. Photographed by U. Woermann, MD, Division of Instructional Media, Institute for Medical Education, University of Bern, Switzerland.
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Blood film at × 1000 magnification. This image demonstrates tartrate-resistant acid phosphatase (TRAP) activity of lymphocytes. Photographed by U. Woermann, MD, Division of Instructional Media, Institute for Medical Education, University of Bern, Switzerland.
