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International audience; Mature lymphoid B-cell proliferations with hairy cells represent heterogeneous entities where specific diagnosis is difficult but important since it impacts therapeutic management. The clinical cases of variant hairy cell leukemia reported herein illustrate the persistence of a clear interest in the use of splenectomy as a therapeutic alternative. Furthermore, ibrutinib appears to be a promising treatment in patients with relapsed/refractory disease.

Summary Introduction The successful diagnosis of chronic B cell lymphoproliferative neoplasms (B-CLPN) requires the integration of multiple parameters, beginning with clinical information, CBC data, and morphology review. Immunophenotyping is essential and genetic testing may also be necessary. However, the relative value of each specimen or ancillary study in the diagnosis and classification has not been systematically established. We have performed a blinded retrospective review to assess what in our laboratory was the relative value of each specimen type and ancillary study in the diagnostic workup of B-CLPN. Methods A total of 185 cases of PB, BM, spleen and lymph nodes were analyzed for relative value of morphology, IHC, flow cytometry study in the diagnosis of B-CLPN. Results ‘High yield’ specimen was identified in most B-CLPN categories, which was highly predictive of the final WHO diagnosis. Conclusion The goal of this retrospective study was to attempt to assess what was the relative value of morphology, immunophenotype, and molecular/cytogenetic study in various sites in the overall diagnostic process in our institution. We investigated the utility of the ‘high yield’ specimens in achieving the correct final diagnosis. In our study, some B-CLPNs notably splenic marginal zone lymphoma and hairy cell leukemia variant, required all studies for a ‘best fit’ type of diagnosis. In other cases, the morphology of a single specimen type was highly predictive of the final diagnosis, although confirmatory studies are recommended for definitive diagnosis.

Background. Coexistence of second malignancies in patients with hairy cell leukemia is not uncommon. Most second malignancies are solid tumors or other lymphoproliferative disorders. In this study, a case of a tartrate-resistant acid phosphatase (TRAP)-positive hairy cell leukemia variant with the subsequent development of Philadelphia chromosome-positive chronic myelogenous leukemia (CML) is reported. Methods. Routine morphology was performed on the peripheral blood, bone marrow and spleen. Peripheral smears were stained for TRAP. Peripheral blood was studied by two-color flow cytometry for a panel of lymphocytic markers including CD11, CD25, and CD103. Cytogenetic studies were performed on a bone marrow aspirate. Results. A unique case of a hairy cell leukemia variant and CML in a patient who responded to the new purine analog 2-chlorodeoxyadenosine (2-CdA) is presented. Conclusions. The first case of concurrent hairy cell leukemia with CML is reported. Cancer 199575 :2089-92.

The introduction of first alpha-interferon and later the purine analogues has revolutionized the treatment of hairy cell leukaemia (HCL). However, there are still some patients that initially or eventually fail to respond and, thus, there is a need for alternative treatment modalities. We have treated 11 HCL patients (eight relapsing and three newly diagnosed) with a chimaeric monoclonal antibody, rituximab, in a dose of 375 mg/m2 once a week for 4 weeks. The response rate was seven out of eleven (64%) with six complete remissions and one partial remission, all which have lasted between 0 and 34 months (median 14 months). Rituximab appears promising in the treatment of HCL and warrants further studies.