title: [Polyclonal B-cell lymphocytosis with clinical and hematological features resembling hairy cell leukemia].
abstract: A 49-year-old man was admitted to our hospital for investigation of splenomegaly and lymphocytosis. He had no significant past history and was not a smoker. Physical examination revealed massive splenomegaly and no palpable superficial lymph nodes. Hematological examination showed a hemoglobin concentration of 10.5g/dl, a platelet count of 9.8 x 10(4)/microliter, and a leukocyte count of 21.2 x 10(3)/microliter with 70% abnormal lymphocytes. In May-Giemsa stained blood films, the abnormal lymphocytes had round nuclei, abundant, pale cytoplasm, and slightly serrated edges. Phase-contrast microscopic and scanning electron microscopic examinations revealed many long surface villi. Tartrate-resistant acid phosphatase activity in these cells was negative. The abnormal lymphocytes had a CD5-, CD10-, CD11a+, CD11c+, CD19+, CD20+, CD22+ phenotype. These features were similar to those described for a variant form of hairy cell leukemia (HCL-Japanese variant). However, studies of Ig gene rearrangement and expression of sIg revealed a polyclonal proliferation of B cells. On the basis of these findings, this case was diagnosed as hairy B-cell lymphoproliferative disorder, a recently described condition characterized by polyclonal B-cell lymphocytosis and features resembling HCL-Japanese variant. Serological assays for antibodies against Epstein-Barr virus suggested a past infection. Splenectomy alleviated the anemia and thrombocytopenia, but not the lymphocytosis.
authors.affiliation: Center for Hematopoietic Diseases, Ohta Nishinouchi Hospital.
authors.forename: H
authors.initials: H
authors.lastname: Kanbayashi
authors.forename: K
authors.initials: K
authors.lastname: Nagata
authors.forename: T
authors.initials: T
authors.lastname: Tanaka
authors.forename: S
authors.initials: S
authors.lastname: Matsuda
authors.forename: H
authors.initials: H
authors.lastname: Sakuma
authors.forename: Y
authors.initials: Y
authors.lastname: Maruyama
authors.forename: T
authors.initials: T
authors.lastname: Machii
mesh_terms: D015703:Antigens, CD / Q000097:blood; D001402:B-Lymphocytes / Q000473:pathology*; D002455:Cell Division; D003937:Diagnosis, Differential; D015321:Gene Rearrangement; D006801:Humans; D007943:Leukemia, Hairy Cell; D008218:Lymphocytosis / Q000175:diagnosis* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D011947:Receptors, Antigen, B-Cell / Q000235:genetics
chemical_list: D015703:Antigens, CD; D011947:Receptors, Antigen, B-Cell