[Acquired hemophilia A that developed after BNT162b2 mRNA COVID-19 vaccination and worsened following re-vaccination].

An 86-year-old Japanese male patient visited a nearby hospital with painful swelling in his left upper and lower limbs 35 days after the second dose of the BNT162b2 mRNA coronavirus disease-2019 (COVID-19) vaccine. He was referred to our hematological department due to a prolonged activated partial thromboplastin time and was urgently admitted. He was diagnosed with acquired hemophilia A (AHA) based on factor VIII (FVIII) activity of 1.7%, FVIII inhibitor of 152.3 BU/ml, and FVIII-binding antibodies detected by enzyme-linked immunosorbent assay. Immunosuppressive therapy with prednisolone (PSL) at 0.5 mg/kg/day was started owing to the risk of infection due to old age and poor activities of daily living. Hemostasis treatment with bypass hemostatic preparations (rFVIIa preparation, FVIIa/FX) was administered for each bleeding event, such as intramuscular and knee joint bleeding, resulting in good hemostatic effects. Coagulative complete remission was achieved on day 69 with PSL treatment; however, FVIII activity decreased with PSL tapering. AHA relapse with rectus abdominis muscle hematoma was observed after the third vaccination. This is the first Japanese report of AHA after COVID-19 vaccination and the world's first case, in which the presence of anti-FVIII-binding antibodies were observed.

Two cases of follicular lymphoma with MYC gene abnormalities that presented with bone marrow necrosis.

Bone marrow necrosis (BMN) occurs most frequently in hematological malignancies and sometimes in non-hematological disorders. Lymphoid diseases causing necrosis are regarded as high-grade disease. B-lymphoblastic leukemia/lymphoma is the most common malignant cause of BMN. Here, we present two patients with follicular lymphoma (FL) and MYC gene abnormalities who developed BMN. In one case of BMN, the necrosis disappeared in response to chemotherapy, and the patient survived with complete remission. In the other case, BMN remained even after chemotherapy, and effective chemotherapy could not be administered due to suppressed hematopoiesis, which led to the lymphoma worsening and the patient's death. Indolent lymphomas, such as FL, as in these cases, have the potential to develop BMN. It is important to detect the development of BMN and administer chemotherapy early to improve patient prognosis, since severe BMN prevents patients from receiving effective treatment.

[Mediastinal abscess due to Aspergillus in a patient with atypical chronic myeloid leukemia, BCR-ABL1-negative].

A 64-year-old male presented with a rapidly growing anterior mediastinal mass during the clinical course of atypical chronic myeloid leukemia. A needle biopsy performed for suspected myeloid sarcoma revealed the presence of Aspergillus abscess. Early diagnosis of mediastinal abscesses, which are associated with a high mortality rate, can prevent the progression of severity. Infectious abscesses should be considered for prompt qualitative diagnosis in patients with mediastinal masses. Thymoma, germ cell tumor, and malignant lymphoma are the most common anterior mediastinal tumors, whereas infectious abscesses should also be considered when myeloid sarcoma is suspected in patients with an underlying myeloid tumor.

[Recurrence of acquired factor V inhibitor after four years of remission].

Acquired factor V inhibitor (AFV-I) is a rare bleeding disorder wherein autoantibodies are developed against coagulation factor V (FV). The clinical symptoms are variable, from laboratory abnormalities without bleeding to life-threatening hemorrhage. We report herein the case of a patient with AFV-I with two relapses 4 years after the first remission. A 66-year-old male was diagnosed with AFV-I in March 20XX-4. He was treated with prednisolone (PSL) at 50 mg/day and achieved remission within 1 month. PSL dose was tapered to oral administration of 2.5 mg every other day, and long-term remission was maintained. He had been treated with dual antiplatelet therapy (DAPT) for old myocardial infarction. FV activity was markedly reduced to 3.4%, and FV inhibitor was detected (1.0 BU/ml) in May 20XX. We followed the patient without increasing the treatment dose for 2 months, but no spontaneous improvement was seen. Because DAPT was ongoing, we judged that the bleeding risk was high, although only minor bleeding symptoms appeared. PSL was therefore increased to 40 mg/day in June. FV inhibitor rapidly disappeared. When PSL dose was gradually decreased, FV activity decreased, and subcutaneous bleeding occurred in February 20XX＋1. PSL dose was increased again for the second relapse, and the patient achieved remission. Few reports have described recurrent AFV-I, and no cases of two relapses have been reported. We believe that this case report is useful for examining the long-term management of AFV-I.

Successful hemostatic management of major surgery for cervical spondylotic myelopathy in a patient with severe factor XI deficiency.

Factor XI deficiency (FXID) is a rare bleeding disorder caused by mutations in the F11 gene. Spontaneous bleeding in patients with factor XI deficiency is rare, but major bleeding may occur after surgery or trauma. The basic method for hemostatic treatment is replacement of the missing factor using FXI concentrate or fresh frozen plasma (FFP). We report the case of a 72-year-old male with severe FXID who underwent a laminoplasty under sufficient, but minimal, FFP transfusion. Through detailed monitoring of activated partial thromboplastin time (APTT) and FXI activity at the perioperative period, we succeeded in hemostatic management of major surgery without significant blood loss and fluid overload. From the course of this case, we found that measuring FXI activity is superior to measuring APTT. Furthermore, we identified a novel homozygous mutation in F11 [NM_000128.3:c.1041C > A:p.(Tyr347*)] by whole exome sequencing.