The identification of eosinophils by flow cytometry is difficult because most of the surface antigens expressed by eosinophils are shared with neutrophils. Some methods have been proposed, generally based on differential light scatter properties, enhanced autofluorescence, lack of CD16 or selective positivity of CD52. Such methods, however, show several limitations. In the present study we report a novel method based on the analysis of glycosylphosphatidylinositol (GPI)-linked molecules. The combination of CD157 and FLAER was used, since FLAER recognizes all GPI-linked molecules, while CD157 is absent on the membrane of eosinophils and expressed by neutrophils. Peripheral blood samples from normal subjects and patients with variable percentages of eosinophils (n = 31), and without any evidence for circulating immature myeloid cells, were stained with the combination of FLAER-Alexa Fluor and CD157-PE. A FascCanto II cytometer was used. Granulocytes were gated after CD33 staining and eosinophils were identified as CD157^-/FLAER⁺ events. Neutrophils were identified as CD157⁺/FLAER⁺ events. The percentages of eosinophils detected by this method showed a very significant correlation both with automated counting and with manual counting (r = 0.981 and 0.989, respectively). Sorting assays were carried out by a S3 Cell Sorter: cytospins obtained from CD157^-/FLAER⁺ events consisted of 100% eosinophils, while samples from CD157⁺/FLAER⁺ events were represented only by neutrophils. In conclusion, this method shows high sensitivity and specificity in order to distinguish eosinophils from neutrophils by flow cytometry. However, since CD157 is gradually up-regulated throughout bone marrow myeloid maturation, our method cannot be applied to cases characterized by immature myeloid cells. [J Clin Exp Hematop 55(2) : 55-60, 2015]

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　 Angioimmunoblastic T-cell lymphoma (AITL) is considered to originate from follicular helper T (T_FH) cells. Currently, neoplastic cells in AITL are considered to express CXCL13 as a tumor marker. However, the identification of CXCL13⁺ cells remains unclear in terms of whether they are neoplastic cells (or T_FH cells) or follicular dendritic cells (FDCs) in both AITL and normal germinal centers. Therefore, the exact identification of CXCL13⁺ cells was performed using 33 cases of AITL and normal germinal centers. Single-labeling immunohistochemistry and double-labeling immunofluorescent microscopy first confirmed that CXCL13 was expressed mainly in FDCs in the normal germinal centers. In 28 of 33 AITL cases, CXCL13 was expressed mainly in FDCs as a meshwork pattern, which was associated with CXCL13⁺ neoplastic cells. In the other five cases, CXCL13 was expressed mainly in neoplastic cells, which were densely distributed in and around the FDC meshwork. These findings indicate the abundance of CXCL13⁺ cells in the FDC meshwork irrespective of the cell type. Triple-labeling immunofluorescent microscopy showed that the CXCL13⁺ FDC meshwork in AITL harbored both neoplastic cells and B cells. CXCR5, the cognate receptor of CXCL13, was expressed in neoplastic cells in AITL. The present study suggests that neoplastic cells in AITL preserve a certain level of T_FH-cell function since neoplastic cells and B cells are closely enmeshed in the CXCL13⁺ cell-rich FDC meshwork in a similar way as in normal germinal centers. [J Clin Exp Hematop 55(2) : 61-69, 2015]

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　 A diagnosis of acute promyelocytic leukemia (APL) is usually made when normal hematopoietic cells are substituted by APL cells. We encountered a unique APL patient who presented with persistent hypoplastic features of APL. An 84-year-old man presented with leukopenia (2.2 × 10⁹/L) and anemia (Hb 12.5 g/dL). Five months later, the bone marrow (BM) was hypoplastic with a normal proportion of blasts and promyelocytes (5.2%), although the latter cells were hypergranular. The karyotype of BM cells was 46, XY, t(15;17)(q22;q12), t(9;11)(q13;p13). Two months later, the BM remained hypoplastic with 8.5% hypergranular promyelocytes, some of which contained faggot of Auer rods. RT-PCR examination yielded the PML-RARα transcript, and its sequencing revealed the breakpoint of PML to be bcr2. The patient was treated with all-trans retinoic acid under a diagnosis of APL with improvement of the bicytopenia. FISH analysis of BM cells yielded a negative result regarding t(15;17), although RT-PCR was positive for PML-RARα mRNA. Six months later, APL recurred with the same karyotypic abnormalities and therapeutic resistance, and the patient died of pneumonia. A persistent hypoplastic state of APL may be a rare event, and the association of t(15;17) and t(9;11) is novel. [J Clin Exp Hematop 55(2) : 71-76, 2015]

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　 Persistent polyclonal B-cell lymphocytosis (PPBL) is a rare clinical condition, characterized by a persistent, generally moderate lymphocytosis, generally due to stimulation of central memory B-lymphocytes, and by a moderate increase of polyclonal IgM. In some patients, slight or moderate splenomegaly is observed. A variable percentage of circulating, bone marrow and splenic lymphocytes display an abnormal nucleus (generally bilobated) or are binucleated. The clinical course is benign in most cases and transformation into splenic B-cell lymphoma occurs in few cases. In the current paper we report the first case of pregnancy in PPBL. Our patient became pregnant 18 months after diagnosis. In the course of pregnancy, a marked down-regulation of lymphocytosis (from 6 × 10⁹/L to 2.1 × 10⁹/L) and a decrease in B-lymphocyte number was observed (from 3.6 × 10⁹/L to 1 × 10⁹/L), mainly due to a marked reduction in the percentage and absolute number of central memory B-cells. Such modifications were similar to those described in normal pregnant women. One year after the delivery of a healthy female baby, the number of total lymphocytes and B-lymphocytes showed an inverse behavior, with a new expansion of central memory B-cells. Our case shows that a normal pregnancy can occur in patients with PPBL and that pregnancy can induce marked modifications in B-lymphocyte kinetics and phenotype. [J Clin Exp Hematop 55(1) : 77-82, 2015]

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　 A 60-year-old male patient suffered from mild exertional dyspnea, wheezing, and systemic blisters. He was diagnosed with paraneoplastic pemphigus (PNP) with follicular lymphoma in the pancreas head and pelvic cavity. He was first treated with eight cycles of rituximab; his blisters and erosions gradually improved and highly elevated levels of auto-antibodies related to PNP gradually decreased to normal levels. However, obstructive and restrictive respiratory failure still progressed. Computed tomography of the inspiratory and expiratory phases revealed obstructive pulmonary disorder, leading to a diagnosis of bronchiolitis obliterans (BO). The patient underwent plasma exchange and was repeatedly treated with rituximab monotherapy and rituximab-containing chemotherapies, but died 7 months after the diagnosis of BO. Early introduction of rituximab-containing regimens may be necessary to prevent the development of BO accompanying PNP. However, when a diagnosis of PNP-related BO is made, lung transplantation may also be considered for patients in whom rituximab-containing regimens are effective for PNP. [J Clin Exp Hematop 55(2) : 83-88, 2015]

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　 Although graft failure (GF) is a fatal and life-threatening complication of umbilical cord blood transplantation (CBT), the standard treatment has not been established. We describe the case of a 28-year-old man diagnosed with acute myelogenous leukemia with myelodysplasia-related changes harboring a normal karyotype. This patient underwent 2 courses of idarubicin and cytosine arabinose therapy, and 3 courses of high-dose cytosine arabinose therapy. Subsequently, he underwent high-dose chemotherapy (total body irradiation and cyclophosphamide) followed by first CBT. Primary GF occurred after post-immunological reaction and hemophagocytic lymphohistiocytosis, and was diagnosed on day 27 after the first CBT. Therefore, the patient underwent secondary CBT for GF treated with a modified one-day conditioning regimen consisting of fludarabine (30 mg/m², 3 days), cyclophosphamide (2 g/m²), and total body irradiation (2 Gy), and graft-versus-host disease prophylaxis consisting of mycophenolate and tacrolimus. Consequently, the patient achieved neutrophil engraftment on day 17 after the second CBT. During the clinical course of the second CBT, the main complications were sepsis, BK virus-associated cystitis, and acute graft-versus-host disease (skin, grade 2, stage 3). After these treatments, the patient was disease-free for 39 months. Our case suggests that these treatments may be feasible, safe, and effective for the treatment of patients with GF. This case study may be helpful to physicians who directly care for GF patients, and may provide a future direction for a more efficient treatment modality. [J Clin Exp Hematop 55(2) : 89-96, 2015]

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　 A 47-year-old woman with marked thrombocytosis of 1,650 × 10⁹/L was diagnosed with chronic eosinophilic pneumonia (CEP) based on imaging of the lung and abundant eosinophils in bronchoalveolar lavage fluid. Known gene abnormalities that cause eosinophilia were not detected in bone marrow cells. Treatment with oral prednisolone at 20 mg/day relieved the CEP and resolved the laboratory abnormalities, including eosinophilia and thrombocytosis. Serum concentrations of interleukin (IL)-5 and IL-6 were elevated to 9.6 and 14.0 pg/mL, respectively. The megakaryocyte-potentiating activity of IL-6 and possibly, that of IL-1β, which is known to be secreted by activated eosinophils, may have caused the marked thrombocytosis in this patient. [J Clin Exp Hematop 55(2) : 97-102, 2015]

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　 Castleman disease is a rare lymphoproliferative disorder that may have a unicentric or multicentric clinical presentation. Herein we present the case of a 49-year-old female with a 3-year history of progressively worsening lymphadenopathy associated with fevers, chills and night sweats. Laboratory studies showed anemia and mildly elevated sedimentation rate. A computed tomogram scan of the chest, abdomen and pelvis showed multiple enlarged bilateral axillary, supraclavicular, subpectoral, submental, retroperitoneal, and para-aortic lymph nodes. A right axillary lymph node biopsy was performed and found to display histopathologic features compatible with the plasma cell type of Castleman disease. The patient was found to be human immunodeficiency virus (HIV)-positive, with a viral load of 104,000/mL and a CD4 cell count of 84 cells/mm³. Molecular studies on the lymph node specimen revealed an incomplete monoclonal DH-JH rearrangement in the IgH gene. The patient was initially treated with antiretroviral therapy with a combination of elvitegravir, cobicistat, emtricitabine and tenofovir that improved her fatigue and malaise. As treatment for Castleman disease, she was administered a combination of rituximab and etoposide, which led to a reduction in lymphadenopathy. To the best of the authors' knowledge, this is the first reported case of multicentric Castleman disease with monoclonal incomplete IgH gene rearrangement in an HIV-positive patient. [J Clin Exp Hematop 55(2) : 103-108, 2015]

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　 In allogeneic hematopoietic stem cell transplantation (allo-SCT) recipients with liver dysfunction, it is often difficult to determine the cause. Several cases of liver dysfunction may be interpreted as chronic graft versus host disease without a definitive diagnosis, resulting in continued immunosuppressive therapy for longer periods. Allo-SCT recipients commonly require frequent red blood cell transfusions during the course of treatment and transplantation, leading to significant iron overload, which could be one of causes of liver dysfunction. Here we report an allo-SCT recipient with chronic deteriorating liver dysfunction due to iron overload, despite maintaining transfusion independence for more than four years. Using magnetic resonance-based liver iron concentration (MR-LIC), iron overload-related liver dysfunction was diagnosed. It drastically improved with monthly phlebotomy and has not recurred following its termination. The observations from our case suggested that iron overload should be recognized as a cause of chronic liver dysfunction even in patients who remain transfusion-independent for several years and that MR-LIC analysis is a useful and reliable method for detecting iron overload and monitoring the effect of iron-reduction therapy. [J Clin Exp Hematop 55(2) : 109-112, 2015]

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　 Waldenström's macroglobulinemia (WM) is a neoplasm of lymphoplasmacytic cells that produces monoclonal IgM protein. Although hyperviscosity syndrome is a common feature of WM, central nervous system (CNS) involvement in WM is rare and is known as Bing-Neel syndrome. A 60-year-old woman was referred to our hospital with bed-bound polyneuropathy, edema, splenomegaly, IgM-λ-type monoclonal protein and CD20-positive lymphocyte infiltration in the bone marrow. She was diagnosed with WM accompanying POEMS syndrome (polyneuropathy, organomegaly, endocrinopathy, monoclonal plasma cell disorder, and skin changes) and was treated with rituximab and thalidomide. She achieved partial remission of WM, and thalidomide was continued for POEMS syndrome. She visited our outpatient clinic 6 years later with sudden onset of vertigo and nausea. Magnetic resonance imaging (MRI) revealed a low-density area 4 cm in diameter in her right cerebrum and right mid-brain and she was referred to our hospital. Pathological analysis of brain biopsy samples revealed diffuse large B-cell lymphoma (DLBCL) in the CNS. Nucleic acid sequence analysis of the VDJ region using DNA obtained from the original WM tumor cells and brain tissue revealed that the DLBCL cells were derived from the original WM malignant lymphoma cells. She received five cycles of rituximab, methotrexate, procarbazine, and vincristine (R-MPV) therapy and 23.4 Gy of whole-brain irradiation followed by two cycles of high-dose cytarabine, which resolved her neurological symptoms in association with reduction of IgM levels to 367 mg/dL. MRI and computed tomography of the brain demonstrated complete remission of her CNS lymphoma. [J Clin Exp Hematop 55(2) : 113-119, 2015]

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