Chronic active Epstein-Barr virus infection (CAEBV) is a disease characterized by clonally proliferating and activated EBV-infected T or NK cells accompanied by chronic inflammation and T- or NK-cell neoplasms. However, the mechanism for developing CAEBV has not been clarified to date. Because the decreased number or inactivation of EBV-specific cytotoxic T lymphocytes (CTLs) resulted in the development of EBV-positive B-cell neoplasms, we investigated the number of CTLs in CAEBV patients using the tetrameric complexes of HLA-restricted EBV-specific peptides. Among the seven patients examined, EBV-specific CTLs were detected in the peripheral blood mononuclear cells (PBMCs) of four cases but were not detected in three cases. The ratio of EBV-specific CTLs in PBMCs tended to be higher in the patients with active disease than in those with inactive disease. In two patients in whom EBV-specific CTLs had not been detected, CTLs appeared after the eradication of EBV-infected T cells by allogeneic bone marrow transplantation. These results suggested that the failure of CTLs had a role in developing CAEBV, although the induction number and function of EBV-specific CTLs might vary in each patient.

Although immunoglobulin light chain (LC) plays a critical role in AL amyloidosis, detailed characteristics of deposited LC are not well known. In this study, LC peptides were analyzed by a combination of laser microdissection, liquid chromatography, and mass spectrometry (LC-MS/MS) in 65 patients with AL amyloidosis. Constant regions of LC were detected in all patients. Kappa- or lambda-types were detected in 20 and 45 patients, respectively. Various types of constant regions of LC were found; however, IGLC3 and IGKC4 were the most frequently detected. Besides LC, apolipoproteins and vitronectin were repeatedly found in amyloid lesions. These results suggest marked heterogeneity in terms of subtype of constant regions of LC in amyloid lesions. Immunohistochemistry identified LC in approximately half of patients in whom LC was detected by LC-MS/MS. This finding indicates superiority of LC-MS/MS over IHC for the detection of LC.

A 59-year-old woman presented with high serum total protein, detected on a screening examination. Laboratory tests revealed high plasma levels of M-protein (IgG-λ), and FDG-PET/CT revealed systemic lymph node swelling and a large tumorous mass in the abdominal cavity. Bone marrow aspirates contained 8.4% plasma cells and approximately 30% abnormal small lymphocytes. A biopsy of the left supraclavicular lymph node was initially interpreted as lymphoplasmacytic lymphoma (LPL). However, chromosomal analysis of the lymph node demonstrated an unusual karyotype with t (14;18) (q32;q21). FISH analysis for the IgH-BCL2 fusion gene was positive. Furthermore, the MYD88 L265P mutation was not detected in tumor cells. Based on these findings, this case was determined to be a type of follicular lymphoma with plasmacytic differentiation. We considered that this case was an important example emphasizing the importance of karyotypic examination for lymphoma classification.

Myelodysplastic syndrome with myelofibrosis (MDS-F) is a disease with a poor prognosis, and patients with this condition are at an increased risk of engraftment failures after allogeneic hematopoietic stem cell transplantation (SCT). Azacitidine (AZA) is effective in high-risk MDS patients. However, the effects of AZA on MDS-F have not been elucidated. AZA was administered to a 62-year-old male with MDS-F for 7 days at a dose of 75 mg/m². Hematological improvements were observed after only 1 course of treatment. No suitable donor was found through the Japan Marrow Donor Program; therefore, the patient underwent umbilical cord blood transplant (UCBT). Neutrophil engraftment was observed on day 21 after the transplant procedure. He developed acute graft versus host disease (GVHD) of the skin (stage 3/grade II), but it could be controlled using prednisolone. Chronic GVHD was not observed and he was discharged in good general condition on day 68. While treatment prior to allogeneic SCT of MDS-F has not been established, in the present case, the hematological improvement brought about by AZA likely contributed to the patient’s positive response to UCBT.

A 66-year-old male underwent prednisolone (PSL) therapy of 13 mg/day for rheumatoid arthritis (RA). Antiphospholipid antibody syndrome, neutrophilic dermatosis (ND), and myelodysplastic syndrome (MDS) developed. Treatment of MDS required red cell concentrate transfusion, and second courses of azacitidine therapy (75 mg/m² daily, intravenous injection for 7 consecutive days) led to hematologic remission. Furthermore, ND improved early after the start of azacitidine therapy, making it possible to decrease the dose of PSL. After 12th courses of azacitidine therapy, treatment was discontinued and the long-term remission of MDS and ND has been maintained. During the course, the level of matrix metalloproteinase-3, as a marker of RA, also decreased. There are few case reports of MDS in which azacitidine was effective for autoimmune diseases, including ND. We report the present case.

Acquired von Willebrand syndrome (AvWS) is a rare bleeding disorder with laboratory findings resembling those of congenital von Willebrand disease. AvWS usually occurs in association with a variety of underlying disorders, such as lymphoproliferative disease or cardiovascular disease, but autoimmune AvWS is very rare. We now describe the case of a 42-year-old woman with autoimmune AvWS with concurrent antiphospholipid syndrome (APS). The patient was suffering from epistaxis and menorrhagia from few years prior to referral. She was referred to our hospital because of Activated Partial Thromboplastin Time (APTT) prolongation. Autoimmune AvWS was diagnosed as hemostatic and immunological analyses showed very low (<6%) levels of vWF ristocetin cofactor activity, low (6%) levels of vWF antigen and the presence of anti-vWF antibodies (IgG1 and IgG2) as well as antiphospholipid antibodies. Steroid therapy led to prompt AvWS remission, but deep vein thrombosis occurred in the left leg, on day 36 and APS was diagnosed. A combination of steroid and anti-coagulant was given for approximately 3 years. Thrombosis has not recurred; but AvWS re-exacerbated with steroid tapering. This is the first case report of autoimmune AvWS concurrent with APS, and the long-term disease course described here can be beneficial to clinicians.

An 8-year-old Mongolian female was diagnosed with acute myeloid leukemia (AML) and treated at a hospital in Mongolia according to the BFM-AML2004 SR protocol. Although complete remission (CR) was achieved, chemotherapy was interrupted because of shortage of drugs. The patient moved to Japan 7 months after diagnosis. Screening for viral infection revealed the presence of hepatitis C virus (HCV) antibody and RNA. At 11 months after initial diagnosis, the patient experienced bone marrow relapse and a RUNX1-RUNX1T1 fusion transcript was detected. Considering the inadequate intensity of initial treatment and the persistent HCV infection, chemotherapy was preferred and initiated over hematopoietic cell transplantation. After the first course of induction therapy, a second CR was confirmed and the chimeric transcript disappeared. The viral load mildly increased during myelosuppression and transient elevation of liver enzymes was observed along with hematological recovery. HCV infection remained stable, without progression to reactivation of hepatitis C. Given the high risk of second relapse and liver fibrosis and sclerosis following chronic HCV infection, treatment against HCV may be indicated during second remission.

Here we present a patient with rheumatoid arthritis (RA), who was suspected to have developed malignant lymphoma during immunosuppressive therapy 5 years earlier. She temporarily achieved remission after discontinuing therapy; however, her disease worsened with remittent fever and splenomegaly. Splenic biopsy demonstrated infiltration by abnormal cells, which were positive for CD56 and T cell intracytoplasmic antigen, but negative for CD3 and Epstein-Barr virus (EBV) -encoded RNA. Cytogenetic analysis of bone marrow and lumbar spine tumor revealed common complex karyotype abnormalities. Thus, she was diagnosed with chronic natural killer cell lymphoproliferative disorder (NK-LPD) and finally died of disease progression. The most common type of LPD in methotrexate-related patients with RA is B-lymphoid LPD, whereas NK-LPD is extremely rare. Furthermore, almost all cases of NK-LPD have been reported to be positive for EBV. This is the first case report on a patient with EBV-negative NK-LPD developed during immunosuppressive therapy for RA.

Multicentric Castleman’s disease (MCD) is a rare, non-malignant lymphoproliferative disorder. We report a case of MCD with multiple liver masses. A 26-year-old woman presented with asymptomatic anemia and hypoalbuminemia. Laboratory tests detected high CRP levels and findings indicative of polyclonal gammopathy. Abdominal CT revealed multiple hepatic large masses (≤10 cm) and partial calcification in the right lobe. Multiple enlarged lymph nodes were also identified in the cardiophrenic angle and porta hepatis. We suspected hepatic malignancy, but pathological examinations of the liver and lymph nodes demonstrated polyclonal plasma cell infiltration and fibrosis. IL-6 staining was positive for plasma cell infiltration of lymph nodes. A few plasma cells were positive for IgG4, and tests for HIV and HHV-8 were negative. Serum IL-6 and plasma VEGF levels were both elevated (45 and 536 pg/ml, respectively). The patient was diagnosed with plasma cell type MCD. We started treatment with PSL 1 mg/kg/day, which led to improvement of anemia, hypoalbuminemia, and high CRP levels. Marginal regression of liver masses was also observed. At the last follow-up, the patient had been progression-free for 18 months. To our knowledge, this is the first report of a plasma cell type MCD with liver masses.

A 47-year-old man presented at a local ophthalmological hospital with blurred vision. He had been diagnosed with hypertensive retinopathy and renal failure and was referred to our hospital for treatment. A renal biopsy was done to evaluate pathology of high proteinuria, hematuria, and rapidly progressive glomerulonephritis. Blood pressure remained high despite antihypertensive therapy; anemia and thrombocytopenia gradually progressed. Thrombotic microangiopathy (TMA) was suspected based on red blood cell fragmentation due to hemolytic anemia, thrombocytopenia, and renal failure. However, plasma exchange resolved neither thrombocytopenia nor renal failure, and anemia gradually progressed. Backache suddenly developed 13 days later, and CT findings indicated a retroperitoneal hematoma secondary to bleeding from the kidney. Selective renal artery embolization via angiography stopped the bleeding, but the patient went into hemorrhagic shock. Pathological findings on renal biopsy were identical to those in malignant hypertension, namely an edematous membrane lining, thickened arterioles, and stenosis. We diagnosed thrombotic microangiopathy due to malignant hypertension, without decrease in activities of ADAMTS13 (a disintegrin and metalloprotease with thrombospondin type 1 motif) or its antibodies. Renal failure did not improve, and continuous hemodiafiltration was needed. This procedure stabilized blood pressure and improved the TMA.

Hematopoietic cell differentiation is regulated by various lineage-specific transcription factors. In the context of erythroid differentiation, the importance of GATA-1 has been unequivocally demonstrated by cell-based ex vivo assays, as well as knockout mouse models and rare patients with anemias. GATA-1 regulates the expression of erythroid-related genes, such as globins and genes involved in heme biosynthesis, by recognizing the DNA binding consensus sequence [(A/T) GATA (A/G)] through dual zinc finger motifs. GATA-1 forms a complex with the basic helix-loop-helix transcription factor SCL/TAL1, another master regulator of hematopoiesis. SCL/TAL1 forms a complex containing LMO2, LDB1, and ETO2, which are all required for GATA-1 activity during the erythroid differentiation. Here we focus on the current understanding of transcriptional regulation of erythropoiesis.

Mitophagy is a mitochondrial quality control mechanism where damaged and surplus mitochondria are degraded by macroautophagy. Mitophagy is associated with various physiological and pathological events such as mitochondrial clearance during the terminal differentiation of reticulocytes. There are two different mammalian autophagy pathways: the Atg5-dependent conventional pathway and Atg5-independent alternative pathway; the latter is involved in reticulocyte’s mitophagy.

Epigenetic regulation holds a key role in gene expression due to its modulation of the structure and function of chromatin. Notably, epigenetic dysregulation is deeply involved in the pathogenesis of hematological malignancies. Polycomb group (PcG) genes encoding histone modifier proteins are representative epigenetic genes that regulate a variety of cellular functions, including self-renewal and multi-lineage differentiation of stem cells. Surprisingly, many PcG genes are targeted by deletions or somatic mutations or both in a number of hematological malignancies, such as myelodysplastic syndrome (MDS). PcG proteins form multiprotein complexes and exert either oncogenic or tumor-suppressive functions, depending on the tumor type. In MDS, they function as tumor suppressors. This review summarizes the current knowledge on deregulated polycomb function in the pathogenesis of MDS.

Refractory cytopenia of childhood (RCC) was proposed as a provisional entity in the 2008 WHO classification of myelodysplastic syndromes (MDS). It is defined as a childhood MDS featuring persistent cytopenia without increase blasts in bone marrow (BM) or peripheral blood (PB). Because the majority of RCC cases feature hypocellularity and pancytopenia, it is quite challenging to differentiate RCC from acquired aplastic anemia (AA) and many kinds of inherited bone marrow failure syndromes (IBMFS). Diagnosis of RCC requires BM histology of characteristic features such as isolated erythroid islet with left shift, abnormal localization and micromegakaryocytes. The Japanese Society of Pediatric Hematology/Oncology has opened the central registry review system since 2009 to evaluate childhood cases of bone marrow failure (BMF). It has reviewed cytology and BM pathology of all registered BMF cases, which number more than 1,700. In the evaluation of BMF, BM pathology is important to assess the mechanism of hematopoiesis. Pathological dysplasia should be differentiated from cytological dysplasia. A central review system is important for rare diseases, such as pediatric BMF. Standardization of pathological diagnosis should be established upon consensus findings, descriptions, and diagnostic approaches. In this review, the pathology of pediatric BMF syndromes is summarized.

Diffuse large B-cell lymphoma (DLBCL), not otherwise specified, is the most common malignant lymphoma in the world. The recent progress of molecular techniques has proved its heterogeneity. Gene expression profiling for DLBCL, recently achieved using formalin-fixed paraffin-embedded samples, has identified two molecular subtypes, according to their cell of origin correlated with prognosis. Genomic abnormalities are roughly divided into translocations, amplifications/deletions, and mutations. Translocations involving MYC and BCL2 frequently co-occur in 5%-10% of DLBCL and are associated with aggressive clinical behavior with poor outcomes. Array CGH has identified some genetic alterations including deletions of tumor suppressor genes, such as CDKN2A, and amplifications of several genes involved in oncogenic pathway, such as NFκB. The next generation sequence identified numerous somatic gene mutations in DLBCL. Mutations of epigenome-associated genes, tumor suppressor genes, and NFκB-associated genes have been identified in cases of DLBCL. These mutations affect the function of gene products and play important roles in lymphomagenesis or the progression of DLBCL. This fact suggested that these mutations may affect clinicopathological findings, particularly prognosis. In this study, the most recent advances in genetic alterations and their association with clinicopathological findings of DLBCL were introduced and reviewed.

Adult T-cell leukemia/lymphoma (ATL) is a peripheral T-cell malignancy caused by human T-lymphotropic virus type I (HTLV-1), and its prognosis remains poor. Three to five percent of HTLV-1 carriers, infected mainly by breast feeding, develop ATL after a latency period as long as 70 years. The standard of care for aggressive ATL and indolent ATL comprises intensive chemotherapy followed by allogeneic hematopoietic stem cell transplantation, if applicable, and watchful waiting, respectively. Outside Japan, a combination of interferon-α and zidovudine has also been used as a therapeutic option for acute, chronic, and smoldering-type ATLs. A Japanese nationwide retrospective study revealed the outcome of patients diagnosed between 2000 and 2009. The median survival times were 8.3, 10.6, 31.5, and 55.0 months and the 4-year overall survival rates were 11%, 16%, 36%, and 52% for acute, lymphoma, chronic, and smoldering-type ATLs, respectively. Recently, the development of several novel agents has been attempted by targeting surface antigens on ATL cells such as CCR4 and CD30 with monoclonal antibodies, targeting molecular abnormalities in ATL cells with EZH1/2 inhibitor, and modulating the immune environment via immunomodulatory drugs (IMiDs) or immune checkpoint inhibitors. Among them, a CCR4 monoclonal antibody mogamulizumab, and an IMiD, lenalidomide, have been introduced for clinical use in Japan.