Acquired Hemophilia After a Spider Bite

Abstract 4637

A 59 year old white female with no history of bleeding diathesis presented with swelling of her left forearm two days after a brown recluse spider bite. Hematology was consulted for uncontrolled bleeding from the fasciotomy site after compartment syndrome. The hand surgeons did not see any vascular abnormality at the site of surgery. Due to ongoing bleeding for days from the surgical site, she required 8 PRBCs, 6 FFPs and 6 apheresis platelets units. PT, PTT, and platelet count were normal, ristocetin cofactor was 339% and vWF antigen 306% and vW Factor VIII binding capacity was normal. Her platelet functional assay was normal. Factor levels of II, V, VII, XI, X, XI and lupus anticoagulant were all with in normal range. A Bethesda assay however showed a low titer of antibody against factor VIII (1.25 BU). Factor VIII was low at 6% and remained low at 16% with no significant response to recombinant factor VIII.The bleeding however responded well to recombinant factor VIIa. She was maintained on high dose steroids for few months and tapered. She eventually had a skin graft to the site of injury and is now followed in our hemophilia clinic with no further bleeding complications.

To our knowledge only one case of spider bite resulting in factor VIII inhibitor has been documented in the literature. We hypothesize that direct antigenic stimulation by spider venom can transiently develop factor VIII inhibitor in individuals.