Hairy cell leukemia variant: Fact or fiction

Department of Pathology, University of Utah, Salt Lake City, 84132, USA.
American Journal of Clinical Pathology (Impact Factor: 2.51). 02/2005; 123(1):132-8. DOI: 10.1309/8QYT-YQ1C-LQMH-Q9CL
Source: PubMed


Hairy cell leukemia variant (HCL-V) is a poorly described, rare B-cell lymphoproliferative disorder typically positive for CD103 and CD11c, while lacking CD25. Splenic marginal zone lymphomas (SMZL) also have this unusual phenotype in 15% to 25% of cases, have other overlapping clinical or morphologic features, and are more common than HCL-V. The purpose of our study was to better characterize HCL-V and determine whether most cases could be distinguished from SMZL. Cases with an HCL-V phenotype were identified from our flow cytometry service, and 10 were selected for further study based on bone marrow or splenic tissue availability. All cases had cytologic features consistent with HCL-V, and 9 of 10 patients had lymphocytosis. Bone marrow involvement was mostly interstitial and/or sinusoidal without lymphoid nodules. Coexpression of preswitched with postswitched heavy chain isotypes, an unusual feature of HCL, was seen in 2 of 4 cases. This study better defines HCL-V and establishes that most cases do not represent SMZL.

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    • "The neoplastic cells also have circumferential cytoplasmic projections but a prominent nucleolus and basophilic cytoplasm are common. Although the patients typically present at an older age with higher numbers of circulating hairy cells than observed in HCL, there is overlap in the spectrum of clinical features [1] [11] [13]; Furthermore the prominent nucleoli characteristic of HCL-v may be absent [14]. HCL-v is a more aggressive disease, with significantly shorter median survival and poor response to purine analogs [1] [5]; however, complete remission has been achieved with rituximab and BL22 [8] [15]. "
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    ABSTRACT: Hairy cell leukemia (HCL) and hairy cell leukemia-variant (HCL-v) are rare diseases with overlapping clinico-pathological features. We performed flow cytometry analysis (FCM) of 213 cases (169 HCL, 35 HCL-v, 9 splenic marginal zone lymphoma (SMZL)), correlating results with available corresponding clinical and morphological data. FCM distinguished HCL-v from HCL and SMZL based solely upon expression of four antigens (CD11c, CD25, CD103, CD123) combined with B-cell markers (CD19, CD20, CD22). HCL-v expressed bright CD20, bright CD22, CD11c(100%), CD103(100%), dim(40%) or negative(60%) CD123, and uniformly lacked CD25(100%). HCL expressed bright CD20, bright CD22, bright CD11c, bright CD25, CD103, and bright homogeneous CD123(100%). Aberrant expression of CD5(2%/3%), CD10(12%/3%), CD23(21%/11%), CD38(14%/0%), CD2(2%/9%), CD4(0.5%/0%) and CD13(0.5%/3%), was observed in HCL/HCL-v, respectively. SMZL cases were CD103(-) and CD123(-) except for one case with dim CD123. HCL showed significantly greater marrow infiltration over HCL-v. Prominent nucleoli were observed in most HCL-v but rarely in HCL. A third of HCL and HCL-v marrows were hypocellular or aplastic-appearing. Detection of BRAFV600E mutation and annexin A1 were examined in a subset of cases to further validate FCM diagnostic criteria. HCL-v was negative for both annexin A1 (100%) and BRAFV600E mutation (100%), in contrast to HCL (74% positive for annexin A1; 76% positive for BRAFV600E mutation). HCL-v is resistant to traditional HCL therapy, making accurate diagnosis imperative. We have defined FCM criteria for differentiation of HCL-v from HCL and SMZL.
    Leukemia research 01/2013; 37(4). DOI:10.1016/j.leukres.2012.11.021 · 2.35 Impact Factor
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    • "In particular, circulating villous lymphocytes have been described in splenic MZL involving the peripheral blood. The distinction of MZL and HCL is made more difficult by overlapping phenotypes: MZL is often CD11c positive and may be positive for CD103 [50] [51]. However, MZL usually demonstrates weaker more variable staining for CD11c than HCL, lacks the combination of CD103, CD11c, CD25, and lacks bright intensity staining for CD20 and CD22. "
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    ABSTRACT: Evaluation of B-lymphocytes is one of the most well-established clinical applications of flow cytometric immunophenotyping. Using this technique, B-lymphocytes are recognized by expression of lineage-associated antigens; the profile of antigens expressed identifies B-cells at different stages of maturation and belonging to different biologic compartments; neoplastic B-cells can be distinguished from reactive B-cells by demonstration of immunoglobulin light chain restriction or phenotypic aberrancy; and the phenotype of the neoplastic cells can be used to identify one of the distinct disease entities recognized in the World Health Organization classification [1]. However, because of overlapping phenotypes, flow cytometric immunophenotyping is often used in conjunction with other studies as part of a multiparametric approach to the diagnosis of B-cell lymphoid neoplasms [1]. This article addresses general principles of the flow cytometric evaluation of B-cell lymphoid neoplasms, followed by discussion of how flow cytometric data can assist in determining a list of diagnostic possibilities and directing additional testing.
    Clinics in Laboratory Medicine 10/2007; 27(3):487-512, vi. DOI:10.1016/j.cll.2007.05.003 · 1.37 Impact Factor
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    • "Specifically, the marrow infiltrates have the ill-defined and well-spaced appearance that typifies HCL, although fibrosis generally is mild or absent. There may be a sinusoidal growth pattern of infiltration [69]. As well, the selective granulocytic hypoplasia that characterizes HCL is not typical of HCL-V. "
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    ABSTRACT: The pathology of HCL has been reviewed with a focus on the diagnostic hematopathology of this rare, but fascinating, disease. The discrimination of HCL from other B-cell lymphoproliferations, particularly HCL-V and SMZL, has been emphasized. The unique responsiveness of HCL to 2-CdA and other chemotherapeutic agents makes this distinction critical. Fortunately, HCL has consistent cytologic, histologic, cytochemical, and immunologic features that make classification reliable and reproducible. Less straightforward is the differential diagnosis of SMZL and HCL-V, problematic because of the rarity of both disorders, lack of discriminating evidence-based criteria, and perhaps a biologic kinship between these two disorders that share many clinical and pathologic features. Fortunately, this is not a clinically critical distinction.
    Hematology/Oncology Clinics of North America 11/2006; 20(5):1023-49. DOI:10.1016/j.hoc.2006.06.010 · 2.30 Impact Factor
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