自己免疫性後天性凝固因子欠乏症

RATIONALE: Acquired hemophilia A (AHA) is a rare bleeding disorder characterized by the development of autoantibodies directed against coagulation factor VIII (FVIII). Approximately 50% of cases are idiopathic, while the remaining are associated with autoimmune conditions, malignancies, or infections. To date, there have been no reported cases of AHA secondary to Flavobacterium odoratum (Frullania odoratum) infection. PATIENT CONCERNS: A male patient underwent ureteroscopic lithotripsy with double-J stent placement. Postoperatively, he developed hematuria, a right medial thigh hematoma, fever, and abnormal coagulation parameters, including prolonged activated partial thromboplastin time (APTT). DIAGNOSES: The diagnosis of AHA was confirmed based on prolonged APTT, markedly reduced FVIII:C, and detection of a factor VIII inhibitor. Additionally, the patient had a complicated urinary tract infection caused by multidrug-resistant F.odoratum, which preceded the onset of AHA. INTERVENTIONS: Doxycycline was administered to treat the catheter-associated urinary tract infection caused by F.odoratum. Hemostatic control was achieved with activated prothrombin complex concentrate. Immunosuppressive therapy for AHA included dexamethasone and cyclophosphamide. OUTCOMES: At discharge, bleeding had resolved, APTT normalized, FVIII activity returned to normal levels, the FVIII inhibitor was undetectable, and the infection was successfully controlled. LESSONS: AHA is a rare but potentially life-threatening condition. Early recognition, prompt treatment, and identification of underlying triggers are crucial to reducing mortality and improving outcomes. This is the first reported case of AHA associated with F. odoratum infection. Clinicians should consider this pathogen in patients with long-term indwelling urinary catheters who present with unexplained infections or bleeding diatheses.

We report the case of an 80-year-old woman in which marked prolongation of prothrombin time (PT) and activated partial thromboplastin time (APTT) noted upon diagnosis of autoimmune hemolytic anemia revealed severe factor V (FV) deficiency. A mixing study showed a downward-convex pattern and the Bethesda assay for inhibitors was negative, which initially suggested congenital FV deficiency. Although the patient had concomitant early-stage esophageal cancer, infusions of fresh frozen plasma (FFP) failed to correct the coagulopathy, necessitating postponement of endoscopic therapy. Subsequently, a comprehensive evaluation by the Standardization Committee of the Japanese Ministry of Health, Labour and Welfare detected anti- FV IgG, establishing the diagnosis of hyperclearance-type autoimmune FV deficiency (AiFVD). Despite corticosteroid therapy, conventional coagulation screening test results remained markedly abnormal, complicating periprocedural management. In contrast, viscoelastic testing (VET) and thrombin generation testing (TGT), including ex vivo supplementation assays, indicated that adequate hemostasis could be achieved, allowing the endoscopic treatment to proceed safely. This case underscores that, even in FV deficiency with a negative inhibitor screen, testing for anti-FV IgG is essential for identifying hyperclearance-type AiFVD. Furthermore, ex vivo VET and TGT provided actionable assessments of hemostatic capacity and proved useful for guiding management in AiFVD.

Acquired hemophilia A is a rare but potentially life-threatening autoimmune bleeding disorder caused by the sudden development of neutralizing autoantibodies against factor VIII (FVIII), predominantly affecting older adults. Because of the risk of severe bleeding and excess mortality, prompt hospitalization and immediate management are essential to avoid diagnostic and therapeutic delays. Diagnosis relies on the association of an isolated prolonged activated partial thromboplastin time, reduced FVIII activity, and detection of a FVIII inhibitor quantified using the Bethesda or Nijmegen assay. Management has 2 complementary objectives. First, hemostatic therapy combines preventive measures with treatment of acute bleeding episodes, using bypassing agents (recombinant activated FVIII or activated prothrombin complex concentrate) or recombinant porcine factor VIII as first-line options. More recently, prophylaxis with emicizumab has emerged as a promising strategy to reduce recurrent bleeding, with early clinical data suggesting favorable efficacy and safety. Second, inhibitor eradication relies on immunosuppressive therapy, typically corticosteroids alone or in combination with agents such as cyclophosphamide or rituximab, guided by baseline FVIII activity and inhibitor titer. Close and prolonged follow-up is mandatory, combining clinical assessment of bleeding control, recurrence risk, and treatment toxicity, with laboratory monitoring of hemoglobin, factor VIII activity, von Willebrand factor levels, and inhibitor titers. Surveillance should be maintained for at least 2 years after complete remission.

Acquired hemophilia A (AHA) is a rare autoimmune bleeding disorder caused by autoantibodies against factor VIII (F VIII). The coexistence of AHA with lupus anticoagulant (LAC) is incredibly uncommon and presents a significant diagnostic challenge, as both conditions prolong activated partial thromboplastin time (aPTT) and demonstrate incomplete correction on mixing studies. We report a case of a 79-year-old man with no prior bleeding history who presented with severe anemia and a retroperitoneal hematoma following a fall. Laboratory evaluation revealed markedly prolonged aPTT, severely reduced F VIII activity (<7%), and an exceptionally elevated inhibitor titer (1084 Bethesda units), consistent with AHA. Concurrently, anticoagulant testing was done with a positive LAC presence. Extensive workup failed to identify an underlying etiology. The patient was subsequently treated with rituximab and corticosteroids, resulting in a gradual decline in aPTT and inhibitor titers with clinical improvement. This case highlights the importance of comprehensive coagulation testing in patients with unexplained bleeding and prolonged aPTT, as the coexistence of prothrombotic and hemorrhagic conditions can obscure diagnosis and delay appropriate management.

Acquired haemophilia A (AHA) is a rare autoimmune bleeding disorder caused by neutralising antibodies against factor VIII. We describe an older man with prostate cancer on active surveillance who presented with spontaneous ecchymoses, progressive anaemia and isolated prolongation of activated partial thromboplastin time. Factor VIII activity was severely reduced, and mixing studies and Bethesda assay confirmed a high-titre factor VIII inhibitor. He achieved initial haemostatic control with recombinant-activated factor VII and was transitioned to emicizumab using an accelerated AHA regimen. No corticosteroids were given inpatient. Emicizumab was used for haemostatic prophylaxis while outpatient once-weekly rituximab was planned for inhibitor eradication. This case highlights early recognition, evaluation for associated malignancy and use of emicizumab as prophylaxis that may allow individualised immunosuppression in selected older patients.