Reference guide for the diagnosis of adult primary immune thrombocytopenia, 2023 edition.

Primary immune thrombocytopenia (ITP) is an autoimmune disorder characterized by isolated thrombocytopenia due to accelerated platelet destruction and impaired platelet production. Diagnosis of ITP is still challenging because ITP has been diagnosed by exclusion. Exclusion of thrombocytopenia due to bone marrow failure is especially important in Japan because of high prevalence of aplastic anemia compared to Western countries. Hence, we propose a new diagnostic criteria involving the measurement of plasma thrombopoietin (TPO) levels and percentage of immature platelet fraction (RP% or IPF%); 1) isolated thrombocytopenia with no morphological evidence of dysplasia in any blood cell type in a blood smear, 2) normal or slightly increased plasma TPO level (< cutoff), 3) elevated RP% or IPF% (> upper limit of normal), and 4) absence of other conditions that potentially cause thrombocytopenia including secondary ITP. A diagnosis of ITP is made if conditions 1-4 are all met. Cases in which criterion 2 or 3 is not met or unavailable are defined as "possible ITP," and diagnosis of ITP can be made mainly by typical clinical course. These new criteria enable us to clearly differentiate ITP from aplastic anemia and other forms of hypoplastic thrombocytopenia and can be highly useful in clinical practice for avoiding unnecessary bone marrow examination as well as for appropriate selection of treatments.

Allo-anti-M: Detection peaks around 2 years of age, but may be attenuated by red blood cell transfusion.

BACKGROUND: Anti-M is frequently observed as a naturally occurring antibody of little clinical significance. Naturally occurring anti-M is often found in children although the specific triggers of production, persistence, and evanescence of anti-M have yet to be elucidated. METHODS: In a retrospective, multicenter, nationwide cohort survey conducted from 2001 to 2015, alloantibody screening was performed before and after transfusion in 18,944 recipients younger than 20 years. Recipients were categorized into six cohorts based on their age at transfusion; within and among these cohorts, allo-anti-M was analyzed in regard to its production, persistence, and evanescence. RESULTS: In 44 patients, anti-M detected before and/or after transfusion was an age-related phenomenon, with a median age of 2 years and an interquartile range of 1-3 years; anti-M was most frequently detected in a cohort of children 1 to <5 years (0.77%, 31 of 4035). At least five patients were presumed to have concurrent infections. Among 1575 adolescents/young adults (15 to <20 years), no anti-M was detected. Of 29 patients with anti-M prior to transfusion, the antibody fell to undetectable levels in 17 recipients (89.5%, of whom at least 13 received only M-negative red cells) after anywhere from 5 days to 5.8 years; anti-M persisted in 2, and was not tested in 10. Only 15 recipients (0.08%) produced new anti-M after transfusion. CONCLUSION: Naturally occurring anti-M is a phenomenon of younger ages, predominantly between 1 and 3 years. After transfusion, it often falls to undetectable levels.

Risk factors for skin, mucosal, and organ bleeding in adults with primary ITP: a nationwide study in Japan.

Bleeding manifestations in primary immune thrombocytopenia (ITP) range from skin petechiae to life-threatening intracranial hemorrhage (ICH). However, the relation between these various bleeding manifestations and the platelet count in ITP remains poorly characterized. Using a nationwide database of patients with ITP during the years 2005 to 2014 (10 years) in Japan, we analyzed 19 415 adult patients newly diagnosed with ITP, including 222 with ICH. The frequency of skin purpura was 64.8%, and this increased linearly with thrombocytopenia without a specific platelet count threshold. In contrast, mucosal bleeding (epistaxis and gingival bleeding) and organ bleeding (melena, hematuria, and ICH) increased exponentially with thrombocytopenia at a platelet count threshold of 10 to 15 × 109/L. Age showed a much weaker correlation than platelet count with skin and mucosal bleeding. However, the incidence of organ bleeding increased exponentially above 60 years of age. Multivariate analysis showed that the presence of mucosal bleeding was a risk factor for occurrence of melena and hematuria but not for ICH. The frequency of ICH was 1.1% and risk factors for ICH were age ≥60 years (odds ratio [OR], 3.09; 95% confidence interval [CI], 2.13-4.47; P < .001), platelet count <10 × 109/L (OR, 2.96; 95% CI, 2.11-4.15; P < .001), and the presence of hematuria (OR, 1.56; 95% CI, 1.04-2.35; P = .033). The relation between ICH and platelet count varied with age. This large-scale analysis of risk factors for bleeding in ITP has revealed distinct characteristics of skin, mucosal, and organ bleeding in adult patients with newly diagnosed ITP, thus indicating those who are at a high risk of severe organ bleeding.

Safe childbirth for a type 1 antithrombin-deficient woman with novel mutation in the SERPINC1 gene undergoing antithrombin concentrate therapy.

: Inherited antithrombin (AT) deficiency is an autosomal dominant thrombotic disorder. We encountered a case of inherited type I AT deficiency and identified the causative mutation; a novel c.7430A>G missense mutation in the SERPINC1 gene in which tyrosine was substituted for cysteine at the 292nd amino acid. A recombinant AT protein with the 7430A>G mutation was not detected in cell lysates or culture supernatants. And then, our patient without personal or family history of thrombosis was pregnant woman with asymptomatic AT deficiency. Our patient treated with only AT concentrate therapy during pregnancy and she was able to safely give birth naturally and avoid thrombosis. We believe that this therapy for pregnant woman with asymptomatic AT deficiency is effective and safety as anticoagulant therapy during pregnancy.

Development of an FVIII Inhibitor in a Mild Hemophilia Patient with a Phe595Cys Mutation.

Mild hemophilia A is caused by a missense mutation in the FVIII gene that is responsible for a decrease in the FVIII:C to between 5% and 40%. The development of FVIII inhibitors has been reported in 3-13% of patients with mild hemophilia. Genetic risk factors for the development of inhibitors in mild hemophilia have been investigated. In the present study, we encountered a case of mild hemophilia with an FVIII inhibitor and identified the mutation responsible: a novel Phe595Cys mutation in the FVIII gene. In addition, this study showed that the inhibitor recognized exogenous wild-type FVIII and autologous mutant FVIII.

A novel frameshift mutation leading to inherited type I antithrombin deficiency.

Inherited antithrombin (AT) deficiency is an autosomal dominant thrombotic disorder. We encountered a case of inherited type I AT deficiency and identified the mutation responsible; a novel 5406delA mutation in the SERPINC1 gene appeared to have caused a frameshift with premature termination at amino acid +283. The recombinant AT protein including 5406delA was not detected in cell lysates or culture supernatants. These results will contribute to the creation of an accurate database and define the molecular basis for AT deficiency.

Usefulness of Low-Dose Splenic Irradiation prior to Reduced-Intensity Conditioning Regimen for Hematopoietic Stem Cell Transplantation in Elderly Patients with Myelofibrosis.

The Janus kinase (JAK) 1 and 2 inhibitor, ruxolitinib, was recently approved in Japan and has been effective in many patients with myelofibrosis (MF). Although the inhibitor decreases splenomegaly and relieves MF-related symptoms, allogeneic hematopoietic cell transplantation (HCT) remains as the only curative therapy for MF. The presence of splenomegaly has been reported as a risk factor for graft failure, delayed engraftment, and poor survival. Here, we report two elderly MF patients with massive splenomegaly and a JAK2 V617F mutation. These patients underwent splenic irradiation to decrease splenomegaly prior to HCT with a reduced-intensity conditioning (RIC) regimen. Massive splenomegaly gradually decreased by 4 Gy splenic irradiation. The subsequent RIC regimen involved 4 Gy total body irradiation and fludarabine and intravenous busulfan. In both patients, engraftment failure did not occur, and complete remission was achieved. The splenomegaly decreased, and MF-related symptoms were resolved. Furthermore, the JAK2 V617F mutation disappeared, and fibrosis in the bone marrow regressed. We suggest that splenic irradiation prior to the RIC regimen for HCT in elderly MF patients with massive splenomegaly is safe. Furthermore, the HCT protocols with splenic irradiation should be considered for patients who have not shown clinical benefits to optimal medical management such as treatment with ruxolitinib.

Vancomycin-induced Immune Thrombocytopenia Proven by the Detection of Vancomycin-dependent Anti-platelet Antibody with Flow Cytometry.

Vancomycin-induced thrombocytopenia is a rare adverse reaction that may be overlooked because no specific diagnostic test is currently available. We herein report a patient with vancomycin-induced immune thrombocytopenia who was diagnosed by the detection of vancomycin-dependent anti-platelet antibody with flow cytometry. An IgG antibody in the patient's serum reacted with platelets only in the presence of vancomycin. Severe thrombocytopenia gave rise to life-threatening gastrointestinal bleeding, which was quickly resolved after effective platelet transfusion following the cessation of vancomycin administration. This report suggests that the flow cytometric test is useful for the differential diagnosis of thrombocytopenia and platelet transfusion should be performed after the cessation of vancomycin administration.

Successful rituximab treatment in an elderly patient with recurrent thrombotic thrombocytopenic purpura.

An 81-year-old man presenting with fever, neurological symptoms, thrombocytopenia, and hemolytic anemia was diagnosed with acquired idiopathic thrombotic thrombocytopenic purpura (TTP). His disintegrin-like and metalloproteinase with thrombospondin type 1 motifs 13 (ADAMTS13) activity was <1% and the ADAMTS13 inhibitor titer was 3.2 BU/ml. He received plasma exchange and steroid administration until remission was achieved. Seven months later, he suffered from paralysis of the right hand, hemolytic anemia, and thrombocytopenia. We confirmed TTP recurrence based on ADAMTS13 activity <1% and an ADAMTS13 inhibitor titer of 19.4 BU/ml. Four infusions of rituximab were administered in addition to plasma exchange and steroid pulse therapy. Platelet count recovery was observed within 5 days. No severe side effects related to rituximab occurred. Although rituximab has not been approved for TTP in Japan, we report the efficacy and safety of rituximab in an elderly patient with recurrent TTP. We suggest that rituximab therapy should be started as soon as possible for recurrent TTP in patients with high titers of ADAMTS13 inhibitor.

[Rituximab for managing refractory thrombotic thrombocytopenic purpura: a report of three cases].

About 20% of TTP are resistant to plasma exchange. As reported in a few case reports and small case series, rituximab has been used in the treatment of TTP with some benefit. However, the optimal dosing, frequency, and timing of rituximab remain to be determined. We treated three cases of refractory TTP with rituximab. Case 1 exhibited brain sequelae probably due to the late administration of rituximab, case 2 died before the expected effect of rituximab could occur, and case 3 recovered completely because of the early administration of rituximab. These results suggest that rituximab should be given as early as possible in TTP, but large clinical studies are required to determine the optimal use of rituximab in TTP.

Role of activation-induced cytidine deaminase in the progression of follicular lymphoma.

Activation-induced cytidine deaminase (AID/AICDA) is required for somatic hypermutation and class-switch recombination of the immunoglobulin gene, and for c-myc translocation of germinal center-derived B-cell lymphoma. In the present study, we attempted to clarify the significance of AID associated with c-myc in the progression of follicular lymphoma (FL) using RT-PCR and quantitative real-time PCR. Tissues from the patients with grade 3 FL expressed relatively higher levels of c-myc and AID. The samples taken from a patient with FL who died within 2 years after the start of treatment showed either no or low expression of AID, despite expressing high levels of c-myc. In order to examine the role of AID expression in rapidly progressive FL, the full-length AID transcript was transfected into AID-negative cell lines established from different patients with rapidly progressive FL. This led to the establishment of AID-expressing transfectants with a low proliferation rate and a significantly increased incidence of G(0)/G(1) arrest compared with controls. Our results indicate that AID may act as a negative regulator of cell survival in FL when sufficient c-myc is expressed. Switch-off or low expression of AID after c-myc amplification may correlate with the clinical outcomes of FL.

A new four-way variant t(5;17;15;20)(q33;q12;q22;q11.2) in acute promyelocytic leukemia.

Acute promyelocytic leukemia (APL) is characterized by t(15;17)(q22;q21), which results in the fusion of the promyelocytic leukemia (PML) gene at 15q22 with the retinoic acid alpha-receptor (RARA) at 17q21. We report a patient with APL carrying a new complex variant translocation (5;17;15;20). Spectral karyotyping analysis of bone marrow cells revealed t(5;17;15;20)(q33;q12;q22;q11.2). Fluorescence in situ hybridization with a PML/RARA dual-color DNA probe showed a single fusion signal, and RT-PCR analysis showed PML/RARA fusion transcripts. Complete remission was attained with a course of conventional chemotherapy with all-trans retinoic acid (ATRA). To our knowledge, this is the first report of a four-way translocation of 5q33 and 20q11 involvement in APL.