Hairy Cell Leukemia: An Elusive but Treatable Disease

Abstract

Hairy cell leukemia (HCL) is a unique chronic lymphoproliferative disorder that can mimic or coexist with other clonal hematologic disorders and has been associated with autoimmune disorders. It should be entertained as an alternative diagnosis in patients with cytopenias being assigned the diagnosis of aplastic anemia, hypoplastic myelodysplastic syndrome, atypical chronic lymphocytic leukemia, B-prolymphocytic leukemia, or idiopathic myelofibrosis. Causative etiology or molecular defects remain unclear, although nonspecific chromosomal and molecular changes have been described. The typical presentation is that of a middle-aged man with an incidental finding of pancytopenia, splenomegaly, and inaspirable bone marrow. Treatment with a purine analogue, cladribine or pentostatin, results in extremely high, durable, overall, and complete response rates, although resistance and relapses do occur. A variant subtype exists and is frequently associated with a poor response. Because of its simplified dosing schedule, cladribine is commonly used as the initial therapy. Treatment of relapsed HCL is dictated by the duration of the preceding remission. Relapsed disease after a prolonged remission can often be successfully retreated with the same initial agent. Resistance in typical HCL is treated with the alternate purine analogue. New agents, such as rituximab and BL22, are actively being evaluated and show promising results in both HCL subtypes. This article uses two patients diagnosed with aplastic anemia and recently seen in consultation at our institution as a springboard to discuss the biology, pathogenesis, clinical presentation, diagnostic evaluation, and treatment options of HCL. The Oncologist 2006;11:780-789

Relato de caso de leucemia de células pilosas

“…O diagnóstico da LCP, segundo dados da literatura, é raro em função de sua baixa incidência (2%) entre as leucemias linfoides do adulto (9,21) , sendo ainda maior a responsabilidade dos profissionais de saúde na observação e no diagnóstico preciso dessa patologia.…”

“…O diagnóstico baseia-se na presença de esplenomegalia (21) e no achado de linfócitos vilosos no sangue periférico e na MO, com reação citoquímica positiva para fosfatase ácido tartarato-resistente (FATR), a qual não é achado específico para LCP (15) , além da biópsia da MO, que pode se apresentar hipercelular ou hipocelular, com infiltrado difuso ou focal de células mononucleares com citoplasma abundante (células espaçadas) e aumento de reticulina (15) . O diagnóstico da LCP, porém, é confirmado pela imunofenotipagem por citometria de fluxo, uma metodologia capaz de demonstrar a capacidade de expressão das imunoglobulinas de superfície IgM, IgD ou IgA, além de outros antígenos associados às células B, como CD19, CD20, CD22 e CD79b, ou típicos da LCP, como CD25, CD11c e CD103, com expressão variável de FMC-7 e CD5, CD10 e CD23 negativas São agendados e realizados exames laboratoriais de admissão ao serviço em 7 de maio de 2010 e retorno do paciente para 11 de maio de 2010.…”

Unusual Presentation of Hairy Cell Leukemia: A Case Series of Four Clinically Unsuspected Cases

“…Unusual manifestations can be seen. HCL should be entertained as an alternative diagnosis in patients being considered for the diagnosis of aplastic anemia, hypoplastic myelodysplastic syndrome, atypical chronic lymphocytic leukemia, B-Prolymphocytic Leukemia, and idiopathic myelofibrosis [8].…”

Hairy cell leukemia presenting as multiple discrete hepatic lesions

“…The hairy cells are B cells found in the blood circulation that consist of oval nuclei and abundant cytoplasm with characteristic microfilamentous ("hairy") projections. Patients usually present with cytopenia and splenomegaly due to infiltration of the cells into the bone marrow and spleen [5] . Hepatomegaly can be seen in up to a third of patients [6] .…”