A case of an acquired inhibitor of Factor XIII

Abstract number: P0297

Xiarchopoulou^* P., Andreopoulos† A., Kotsi^* P., Kouramba^* A., Anastasopoulou^* J., Katsarou^* O., Tsoukala^* C., Karafoulidou^* A.

^*2nd BTC Hemostasis Unit, Greece; †A Department of Internal Medicine, Greece

The presence of FXIII circulating autoantibodies is an extremely rare, yet severe bleeding disorder, since FXIIIa is responsible for the covalent cross-linking of a- and b-fibrin chains during the terminal phase of blood coagulation (clot stabilization). Clinical manifestations include spontaneous muscle and subcutaneous hematomas as well as intracranial hemorrhages and require prompt treatment. A 71-year-old man was admitted to Laikon General Hospital with a large muscle hematoma of the right scapula region (Hct: 13%). The patient had no personal nor familial history of bleeding disorders. Both clinical and laboratory evaluation revealed no objective findings. The coagulation screening assay results (PT, APTT, FIB) were also normal. The determination of the activity of FXIII in plasma demonstrated a severe FXIII deficiency (photometric determination of enzymatic activity of FXIIIa on a synthetic substrate, DADE-BEHRING). The presence of aquired inhibitor of FXIII was suspected and confirmed.The patient was initially treated with IV IgG immunoglobulin and Prendisolone with no success. Endoxan (150 mg) was then started daily for a 6-week period of time together with a bolus high dose FXIII substitutive treatment (150 IU kg^-1 BW of FXIII concentrate, Fibrogammin, Behningher). An improvement of patient's clinical condition and Hct stabilization was noted 2 days after the administration of FXIII concentrate. Five days after the initial dose of FXIII concentrate, a repeated dose (100 IU kg^-1 BW) was administrated. The re-evaluation of the patient's clinical condition after 1 month, showed that the hematoma was at 1/3 its initial size. Six months later the patient remains uneventful.