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Acquired coagulation factor V (FV) inhibitors are rare disorders in which antibodies against FV develop under various conditions. We herein report the case of a 71-year-old woman with FV inhibitor during radiochemotherapy for pancreatic cancer. Multiple purpuras suddenly appeared on her bilateral upper limbs with prolonged coagulation data (APTT 97.3 seconds). The FV activity was less than 3% and the FV inhibitor was positive (1.7 B.U./mL). Oral prednisolone induced a rapid normalization of the coagulation data and FV activity and a rapid disappearance of FV inhibitor within 7 days. Early diagnosis and treatment may therefore be important in cases of FV inhibitor.

Acquired factor V inhibitor represents a rare condition, described only in case reports. The use of activated bypassing agents in bleeding control could be of aid and improve the survival in symptomatic patients with acquired factor V inhibitor.

Acquired factor V inhibitor (AFVI) is an extremely rare disorder that may cause severe bleeding. To identify factors associated with bleeding risk in AFVI patients, a national, multicentre, retrospective study was made including all AFVI patients followed in 21 centres in France between 1988 and 2015. All patients had an isolated factor V (FV) deficiency50% associated with inhibitor activity. Patients with constitutional FV deficiency and other causes of acquired coagulation FV deficiencies were excluded. The primary outcome was incident bleeding and factors associated with the primary outcome were identified. Thirty-eight (74 [36-100] years, 42·1% females) patients with AFVI were analysed. Bleeding was reported in 18 (47·4%) patients at diagnosis and in three (7·9%) during follow-up (7 [0·2-48.7] months). At diagnosis, FV was10% in 31 (81·6%) patients. Bleeding at diagnosis was associated with a prolonged prothrombin time that strongly correlated with the AFVI level measured in plasma {r = 0·63, 95% confidence interval (CI) [0·36-0·80], P 0·05}. Bleeding onset during follow-up was associated with a slow AFVI clearance (P 0·001). The corresponding receiver operating characteristics curve showed that AFVI clearance was predictive of bleeding onset with an AFVI clearance of seven months with a sensitivity of 100% (95% CI: 29-100) and a specificity of 86% (95% CI: 57-98, P = 0·02). Kaplan-Meier analysis showed that AFVI clearance7 months increased the risk of bleeding by 8 (95% CI: [0·67-97], P = 0·075). Prothrombin time at diagnosis and time for clearance of FV inhibitor during follow-up are both associated with bleeding in patients with AFVI.

This case report highlights the challenges in controlling bleeding and correcting coagulation tests through the use of bypassing agents in patients with FV inhibitors.

Factor V deficiency is a rare hemostatic disorder. It may present with a diverse spectrum of symptoms due to a variety of mechanisms including development of autoantibodies associated with a number of conditions. We report a first case of factor V deficiency in Tunisian hemodialysis patient due to an autoantibody most likely secondary to antibiotic exposure responsible for an arteriovenous shunt thrombosis rather than bleeding. We discuss here the clinical and biological features of acquired factor V inhibitor and provide a short review of the current literature.

We herein report a patient with a high bleeding tendency as a result of acquired factor V inhibitor and immune thrombocytopenia (ITP). The administration of prednisolone increased the platelet count, but a fatal bleeding event occurred before platelet levels had sufficiently increased. Factor V is stored in not only plasma but also platelets, and platelet-derived factor V might play a local hemostatic role. Bleeding tendency may be high in rare cases where factor V inhibitor is complicated with severe thrombocytopenia. In such patients, physicians should consider aggressive hemostatic therapy, including plasma exchange, in addition to immunosuppressive therapy.

We report a very high factor V inhibitor affecting the measurement of all coagulation factors besides fibrinogen, all these factors being dramatically decreased. This inhibitor could be linked to antibiotic use. The patient died of massive hemorrhage before a plasma exchange could be initiated.

Acquired coagulation factor inhibitor is a rare coagulation disorder. We herein report a patient with acquired factor V inhibitor showing a decrease in multiple coagulation factor activities. A high titer of factor V inhibitor presumably led to a marked inhibition of factor V activity in the specific factor-deficient plasma used in coagulation factor activity assays based on either an activated partial thromboplastin time (APTT) or prothrombin time (PT) clotting assay, resulting in false low values of the coagulation activity. We re-examined the coagulation factor activity using several dilutions of the patient's plasma and confirmed that the high factor V inhibitor titer had caused an apparent decrease in multiple coagulation factor activities.

Rationale: Acquired inhibitors of coagulation are antibodies that either inhibit the activity or increase the clearance of a clotting factor. Acquired factor V deficiency is a rare coagulation disorder, and it can sometimes be life threatening. Patient concerns: We describe a case of a 90-year-old Japanese male with acquired factor V deficiency. He was previously misdiagnosed with congenital factor V deficiency when he presented with hemoptysis and a negative factor V inhibitor test result at a different hospital 5 years earlier. Coagulopathy recurred with ecchymosis when he sustained a bruise after falling on a bush. Diagnosis: Although the factor V inhibitor test result was negative and a mixing study suggested a deficiency pattern, we diagnosed the patient with acquired factor V deficiency on the basis of no history of bleeding diathesis, a lack of response to multiple fresh frozen plasma transfusion, and clinical response to corticosteroid therapy. Interventions: Intravenous methylprednisolone was administered at 500 mg/day for 3 days, followed by oral prednisolone at 1 mg/kg/day. Outcomes: Coagulation test results improved and symptoms resolved 2 weeks after corticosteroid administration. Lessons: This case report suggests that clearance-facilitating antibodies exist without the presence of neutralizing inhibitors. When patients present with coagulation factor V deficiency in the absence of coagulation inhibitors, acquired factor V deficiency should also be considered.

Inhibitors directed against factor V rarely occur, and the clinical symptoms vary. We herein report the case of a patient who presented with a decreased factor V activity that had decreased to 10 years earlier might have caused the development of a factor V inhibitor. The treatment of acquired factor V inhibitors is mainly the transfusion of platelet concentrates and corticosteroids. Both early detection and the early initiation of the treatment of factor V inhibitor are thus considered to be important.

We report a case of acquired factor V inhibitors (AFVIs) in a patient with end-stage renal disease receiving warfarin therapy for atrial fibrillation. A 72-year-old Japanese man was admitted to our hospital complaining of tarry stools and abdominal pain. The laboratory findings revealed eosinophilia (52.1%), prolonged activated partial thromboplastin time (APTT) (98 s), PT (84 s), a factor V (FV) activity of

The occurrence of an inhibitor against coagulation factor V (FV) is a rare but challenging condition, which may span from asymptomatic laboratory abnormalities to potentially life-threatening bleeding. The onset of FV inhibitors has been associated most frequently in the past with the patients' exposure to topical bovine thrombin administered during surgery procedures. However, since this preparation is no longer used, in this systematic review we have only focused on non-bovine thrombin-related FV inhibitor cases.

症例は82歳，男性．40年前から尋常性乾癬に罹患している．2008年11月に転倒し，右前腕，右下腿を受傷したが，受傷部位からの出血が持続するために近医を受診した．血小板数 正常，PT＜5％，APTT＞200秒で，凝固第V因子活性を測定したところ3％未満で，インヒビターは7Bethesda U/mlであった．後天性凝固第V因子欠乏症と診断し，新鮮凍結血漿の投与を行い止血が得られた．その後，第V因子活性は徐々に増加してきたため経過をみていたが，2009年10月，下血をきたしたため再度受診した．第V因子活性の低下とインヒビター力価の上昇を認めた．この時，急性ラクナ梗塞を併発した．下血と梗塞後出血予防のためプレドニゾロンの投与を行ったところ，第V因子活性は速やかに正常となり，インヒビターも消失した．後天性第V因子インヒビターは，数ヶ月以内に自然消失することが多く，免疫抑制剤の効果は確立していない．本例は約1年にわたり凝固異常が持続したが，プレドニゾロンの投与で極めて速やかに改善し，免疫抑制療法の著効例と考えられたため報告する．

Acquired inhibitor of factor V is a rare condition with a variety of clinical manifestations, from extremely mild to life threatening haemorrhage. We present a case from our intensive care unit as a reminder of the less common causes of elevated prothombin and activated partial thromboplastin times, and how knowledge of the variable presentation may aid management.

Coagulation factor V (FV) is an essential component of the prothrombinase complex, which activates the zymogen prothrombin to thrombin. Acquired FV inhibitor is rare and clinical symptoms are quite variable. The aim of this study was to summarize the spectrum of the bleeding presentation of acquired FV deficiency and characterize the underlying causes of the clinical symptoms. This study was designed as a descriptive retrospective and 30 case reports were included for further analysis. At least 33 cases of acquired FV inhibitor were investigated. Most patients have a presentation of bleeding and most of those are from hematuria and bleeding at surgical sites. Seven cases of asymptomatic acquired FV inhibitor were also detected. A total of 39.4% (19 of 33) of those cases with acquired FV inhibitor have an unknown cause. For those with known etiologies, chemical and drug-induced causes are the most common (30.8%).

An 82-year-old man referred to our medical ward because of epistaxis and melena was found to have 12 Bethesda units of factor V inhibitor. He was managed for bleeding with supportive care, followed by corticosteroid therapy. The bleeding completely stopped 1 week after corticosteroid therapy. Medical history revealed dysphagia during the past 6 months and further evaluation brought to light a squamous cell carcinoma (SCC) in the esophagus. This is the first case of an acquired factor V inhibitor developing in a patient with esophageal SCC without any other risk factors such as surgery.

著明な出血傾向を示し, 血液凝固第V因子インヒビターの存在を確認しえた一例を経験したので報告する. 症例は55歳, 男性. 慢性糸球体腎炎による末期腎不全のため1994年から維持血液透析を受けていたが, 2002年6月から出血傾向が出現した. PT, APTTが著明に延長しており, 第V因子活性が1.4%と著明に低下していたため当院に紹介入院となった. PIVKA-IIは正常であり, 正常血漿添加補正試験で補正されなかったため, 先天的な第V因子インヒビターにビタミンK欠乏を合併した可能性は否定され, 第V因子インヒビターの存在が疑われた. 著明な貧血と筋肉内への出血がみられ, 第V因子インヒビターが17ベセスダ単位/mLと高値であったため凍結血漿の輸注や血小板輸血, ステロイドホルモンの投与と血漿交換を行ったが, 第6病日, 突然死した. 透析患者における第V因子インヒビター発現の報告はなく, まれな症例であると考えられた.

Factor V inhibitor is in itself a rare entity. We are reporting a case of an elderly male who presented with symptoms of bleeding and was later found to have developed factor V inhibitors. He had been on amiodarone for atrial fibrillation and developed hemorrhagic manifestations due to factor V inhibitors within a few months of initiating amiodarone therapy. Most of the cases of factor V inhibitors reported in the literature were found to be associated with exposure to bovine coagulation factors. However, in our case there was no evidence of bovine thrombin use during surgery. Furthermore, bovine thrombin-associated factor V inhibitors commonly emerge within 1-2 weeks after exposure during surgery versus several months later in our patient. There was dramatic improvement in the coagulation profile 6 weeks after discontinuation of amiodarone and institution of steroids and cyclophosphamide. We propose the consideration of amiodarone as a contributing agent in inhibitor generation even though a spontaneous development of factor V inhibitor could not be ruled out.