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, they can occur at any age , and the clinical symptoms vary , ranging from asymptomatic laboratory abnormalities to life - threatening bleeding .
the presence of life - threatening factor v inhibitor cases underscores the need for prompt diagnosis and treatment ( 1 ) .
various causes of factor v inhibitors have been reported , and most of the cases described in japan developed after exposure to bovine thrombin preparations , which have been used frequently as topical hemostatic agents in various types of surgery .
however , due to the increasing surgical use of recombinant human or bovine forms of thrombin , at least in developed countries , the number of factor v inhibitor cases associated with these products appears to be in decline . in parallel , attention has lately been focused on other possible causes of factor v inhibitor development ( 2 ) .
we herein report the case of a patient who developed idiopathic acquired factor v inhibitor and died due to an intracerebral hemorrhage .
a 79-year - old japanese woman presented herself to another hospital with left pedal edema .
she also received oral cefcapene pivoxil hydrochloride hydrate to treat her lower urinary tract symptoms .
she was transferred to our hospital because a routine coagulation panel revealed a markedly prolonged prothrombin time of 60 s and an activated partial thromboplastin time of 120 s. her medical history included hypertension , diabetes mellitus , and coronary artery disease ( cad ) .
the cad first manifested as angina in june 2001 , at which time her coronary angiography demonstrated triple vessel disease . in july 2001 , she underwent coronary artery bypass grafting . in december 2012
, she was re - admitted to our hospital because of a worsening angina , and she underwent percutaneous coronary intervention .
subsequently , she underwent percutaneous coronary intervention with a drug - eluting stent in november 2013 .
no previous bleeding tendency was noted , and she had no significant family history of bleeding disorder .
her medication included clopidogrel sulfate , aspirin , cilnidipine , lisinopril hydrate , pravastatin sodium , and nicorandil .
on admission to our hospital in october 2014 , her height was 143 cm and weight was 43.1 kg ; her body temperature was 37.2 , blood pressure 109/47 mmhg , pulse 83/min , clear consciousness , no conjunctival pallor , and no icterus .
. left pedal tender swelling was observed and it was thought to be a hematoma .
the measurement of the coagulation factor profile revealed a marked decrease in factor v activity to 3% and somewhat reduced activities of factors ii , ix , x , xi , and xii .
the test for coagulation factor v inhibitor was positive ( 18 bethesda u / ml ) .
ast : aspartate - aminotransferase , alt : alanine - aminotransferase , -gtp : -glutamyl transpeptidase , ldh : lactate dehydrogenase , bun : blood urea nitrogen , cr : creatinine , ua : uric acid , wbc : white blood cells , rbc : red blood cells , hb : hemoglobin , hct : hematocrit , plt : platelets , pivka - ii : protein induced by vitamin k absence - ii , pt : prothrombin time , pt ( inr ) : prothrombin time international normalized ratio , aptt : activated partial thromboplastin time , fib : fibrin , atiii : antithrombin iii , fdp : fibrin / fibrinogen degradation products , tt : thrombotest , hpt : hepaplastin test , lupus ac : lupus anticoagulant she was given vitamin k and six units of fresh frozen plasma , while the administration of clopidogrel sulfate was stopped , but her coagulation panel did not improve .
on day 3 after admission she slipped into a coma , and an emergent brain computed tomography ( ct ) scan demonstrated she had suffered an intracerebral hemorrhage ( fig .
ct of the head of the patient , a 79-year - old woman , obtained on day 3 after admission . because platelets contain factor v , we transfused 10 units of platelets .
in addition , prednisone 1 mg / kg daily was initiated in an attempt to suppress possible autoantibody production against coagulation factor(s ) . despite these treatments ,
the patient 's plasma demonstrated prolonged phospholipid - dependent in - vitro clotting tests , such as aptt . mixing studies with pooled normal plasma failed to correct the abnormal aptt , in which the incubation time was two hours ( fig .
the levels of phospholipid - dependent clotting factors ( factors ii , v , ix , x , xi and xii ) were low , and we evaluated the possibility of lupus anticoagulant hypoprothrombinemia syndrome , but the dilute russell viper venom time was not measurable in this case .
a laboratory diagnosis of la requires careful adherence to the following criteria : ( i ) the prolongation of at least one phospholipid - dependent clotting test , ( ii ) a failure to correct prolonged screening coagulation test upon mixing with pooled normal plasma , ( iii ) evidence that an inhibitory activity is dependent on phospholipids , and ( iv ) ruling out any other coagulopathies ( such as factor viii inhibitor , heparin ) ( 3 ) .
our patient 's laboratory data were consistent with criteria ( i ) , ( ii ) and ( iii ) , but the level of factor v activity was remarkably low , which was inconsistent with criterion ( iv ) .
in addition , the positivity of factor ii inhibitor might be a false - positive result , due to cross - reactivity with factor v inhibitor .
cross mixing test of the patient , a 79-year - old woman . according to the review by franchini and lippi ( 2 ) , among the conditions associated with
the development of factor v inhibitors , autoimmune disorders were present in 13% of the cases examined , whereas 22% were associated with cancer .
the most common associated condition was the use of antibiotics , such as -lactams , aminoglycosides ( especially streptomycin ) , cephalosporins , tetracyclines and fluoroquinolones ( especially ciprofloxacin ) , which accounted for 42% of the reported cases .
however , it is difficult to establish whether these latter conditions play a causative role in the development of the inhibitor because concomitant antibiotic therapy was also present in almost all cases ( 2 ) .
cases of an acquired factor v inhibitor due to medications , such as rifaximin , dabigatran etexilate methanesulfonate and warfarin have been described ( 1,4,5 ) .
however , our patient 's medications , except for furosemide and cefcapene pivoxil hydrochloride hydrate , had been continually taken for many years without developing any inhibitors .
furthermore , furosemide and cefcapene pivoxil hydrochloride hydrate were initiated after the development of symptoms .
bovine factor v acts as a potent immunological stimulus for the development of anti - bovine factor v inhibitors , which can then cross - react with human factor v. most patients with bovine thrombin - induced autoantibodies showed only coagulation laboratory abnormalities without any hemorrhagic complications , and the antibodies were frequently transient ( 2 ) .
our patient underwent coronary artery bypass grafting about 10 years earlier , and it is unlikely that the surgery had been the cause of the later factor v inhibitor .
ongoing dapt at the time of development of afvi might have contributed the catastrophic outcome in this patient . according to the aforementioned systematic review
, the treatment of acquired factor v inhibitors is based on two steps : the control of the bleeding and the eradication of the antibody .
although treatment is usually unnecessary for asymptomatic patients , a number of therapeutic options have been used in bleeding patients . in a systematic review , 71% had a satisfactory clinical response to the transfusion of platelet concentrates ( 2 ) .
in the same review , immunosuppressive regimens with corticosteroids alone or in association with cyclophosphamide or other immunosuppressants had been used successfully to suppress autoantibody production in 63% , with remission in 76% .
the median time to remission was 6 weeks . in our patient , it is possible that the coagulation profile was not corrected because she had only been treated for 5 days ( 2 ) .
recent studies have demonstrated the effectiveness of rituximab in a number of autoantibody - mediated diseases , including thrombotic thrombocytopenic purpura , autoimmune hemolytic anemia , immune thrombocytopenia and acquired hemophilia due to factor viii inhibitors .
rituximab has been used in three patients with severe pulmonary hemorrhage due to acquired factor v inhibitor ( 6 ) . the early recognition and initiation of treatment for factor
we herein presented a case of factor v inhibitor that resulted in fatal intracranial bleeding .
the earlier recognition of this condition and timely initiation of treatment therefore appear to be of critical importance .
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 <3 % . 
 we administered vitamin k and 6 units of fresh frozen plasma , but she thereafter developed an intracerebral hemorrhage . 
 it is unclear whether surgery > 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 .