Book Review

Hairy Cell Leukemia

N Engl J Med 2000; 343:892September 21, 2000

Article

Hairy Cell Leukemia
(Advances in Blood Disorders. Vol. 5.) Edited by Martin S. Tallman and Aaron Polliack. 189 pp., illustrated. Amsterdam, Harwood Academic, 2000. $65. ISBN: 90-5823-009-0

Hairy-cell leukemia has been the subject of more scientific reports than its rarity might warrant. Many early studies dealt with the morphologic characteristics of hairy cells, the pathological features of involved tissues, tartrate-resistant acid phosphatase as a marker, the cellular lineage of hairy cells, the clinical response to splenectomy, and the dramatic results of treatment with interferon, pentostatin, and cladribine. We now know that cells with “hairs” may not be hairy cells. This cytologic feature may prevail in phorbol ester–stimulated chronic lymphocytic leukemia cells and in splenic lymphoma with villous lymphocytes.

Variants of hairy-cell leukemia include the blastic subtype, the phenotypically unique variant, and the Japanese form. Morphologically, these variants are similar, but their clinical outcomes and responses to treatment may not be. To establish the diagnosis of hairy-cell leukemia, one must rule out splenic lymphoma with villous lymphocytes, lymphoplasmocytic lymphoma, monocytoid lymphoma, and prolymphocytic leukemia. The hairy cells alone, or in concert with other cells, are capable of producing cytokines, which may be responsible for some of the clinical features of the disease.

Three new drugs have produced excellent results. Treatment with interferon alfa results in an 80 percent overall response rate and a 20 percent rate of complete remission. The rate of response to pentostatin may exceed 90 percent, and the rate of complete remission ranges from 41 to 90 percent. The results with cladribine are even better, and many of us now think of hairy-cell leukemia as a curable disease. However, to obtain access to the vast amount of information on hairy-cell leukemia, one must consult many specialty journals. With Hairy Cell Leukemia, Tallman and Polliack have brought together a comprehensive collection of data in a single, practical book.

This book consolidates information on hairy-cell leukemia into 15 chapters written by experts. The chapters on the epidemiologic and clinical features of hairy-cell leukemia reiterate what has been known for some time. The discussion of unusual manifestations is interesting and provides information that is less well known for readers who are new to the subject. The histomorphologic features of the disease and the characteristic hairy cells are adequately described, along with their cytochemical and immunologic phenotype. Although the presence of residual disease in the marrow after treatment can be established immunohistochemically, it usually does not jeopardize long-term remission.

The chapters on electron microscopy, cytogenetics, and molecular genetics are interesting, but these techniques do not provide very useful diagnostic information. The chapters on cell biology, cytokines, and cytokine receptors are informative and interesting, but they do not discuss the mechanisms of the expression of cytokines and their receptors in hairy cells. Many distinctive features of hairy-cell leukemia, such as pseudosinus formation and tissue fibrosis in infiltrated areas and hypersplenism, are likely to be related to cytokine expression. The chapters that summarize the results of treatment with interferon, pentostatin, and cladribine provide comprehensive, meaningful analyses and comparisons of the three drugs.

This book brings together much interesting and useful information. However, many puzzling questions remain unaddressed. For example, why is the hairy cell “hairy”? What is the function of tartrate-resistant acid phosphatase in hairy cells? Is it related to the cell lineage or activation state? Why are the results of treatment so much better in patients with hairy-cell leukemia than in those with chronic lymphocytic leukemia? Although hairy cells are B lymphocytes, they possess many phenotypic characteristics of monocytes. The possibility that hairy-cell leukemia involves cells at the junction of B-lymphoid and myeloid cell differentiation should be considered. Finally, although many effective treatments are available, one should keep in mind that some patients with hairy-cell leukemia may need no treatment at all. Asymptomatic patients with stable and sufficient blood counts and with minimal splenomegaly may have a better quality of life if their few hairy cells are left alone.

This book is a useful account of the vast amount of clinical and pathological information about a rare disease, and clinicians will find it helpful. However, readers interested in the vexing questions that persist about hairy-cell leukemia may be left unsatisfied.

Lung T. Yam, M.D.
Veterans Affairs Medical Center, Louisville, KY 40206