Unusual direct phycoerythrin labeling of B-cells from a splenic marginal zone lymphoma.

Flow cytometry is the most widely used method for lymphocyte subset characterization. Two types of antibodies, directly labeled with fluorochrome, are currently used for immunological diagnosis of B-cell lymphoproliferation: monoclonal antibodies against leukocyte differentiation antigens and polyclonal antibodies against immunoglobulins and light chains. In this study is described the case of a patient with an uncommon immunophenotyping of a B-cell lymphoproliferative disorder. B-cells from peripheral blood and from bone marrow reacted positively with all the tested phycoerythrin (PE)-conjugated antibodies, including the isotypic control. So we thought about a B-cell proliferation carrying a surface receptor recognizing PE: these B-cells were directly labeled with streptavidin-PE, indeed. Moreover, the immunodots from the patient were able to fix the streptavidin-PE. Finally, this unusual immunophenotyping was solved by using antibodies labeled with other fluorochromes than PE.

[A case of de novo acute basophilic leukaemia: diagnostic criteria and review of the literature]. / A propos d'un cas de leucémie à basophiles de novo: critères diagnostiques et revue de la littérature.

We report a case of a de novo acute basophilic leukaemia, revealed by an infectious pneumopathy in a 73 year old man. The full blood count revealed an hyperleucocytosis associated with an unregenerative normocytic normochrom anaemia and a thrombocytopenia. The blood and bone marrow smears showed a mixture of undifferentiated blast cells and basophiloblasts (high nucleo-cytoplasmic ratio, coarse basophilic cytoplasmic granules), along with basophilic precursors and basophilic polymorphonuclears. All the blasts were MPO negative but positive for the toluidine blue metachromatic coloration, which is considered as consistent with basophilic lineage. Immunophenotypic studies showed myeloid blasts, without maturity marker, CD 117 negative and CD203 cytoplasmic positive, the latter known to be highly representative of the basophilic lineage. This very clear-cut phenotype, associated with the morphology of cells, were arguments to ascertain the basophilic lineage of the blasts without the need of electron microscopic study. Cytogenetic and RNA analysis revealed the presence of a Philadelphia chromosome and of a BCR-ABL transcript with the unusual junction e6a2. Thus, imatinib was added to the conventional chimiotherapy and the patient is currently in complete remission. This clinical prompted allows us to review the literature on acute basophilic leukaemia and to state on the different diagnostic criteria of this rare disorder.

[Acquired Von Willebrand syndrome]. / Syndrome de Willebrand acquis.

We report a case of acquired von Willebrand syndrome in association with multiple myeloma, diagnosed in a 54 year-old man suffering from sudden onset of mucocutaneous bleeding. The acquired von Willebrand syndrome is a rare bleeding disorder with laboratory findings similar to those of inherited von Willebrand disease. Diagnosis, etiology and pathophysiology of acquired von Willebrand syndrome are reviewed to establish a differential diagnosis with inherited von Willebrand disease. Identification of the underlying disease responsible for the acquired von Willebrand factor defect and the bleeding diathesis is necessary to choose among the therapeutic options the appropriate treatment.