Acquired factor v inhibitor developing after treatment with dabigatran etexilate methanesulfonate: a case report and review of the literature.

A 90-year-old man presented with subcutaneous ecchymoses. He had been under treatment with dabigatran etexilate methanesulfonate (DEM). Prolonged APTT and decreased PT was developed 2 months after the start of DEM, more prolonged 6 months later. DEM was discontinued, the coagulopathy did not improve. Factor V activity was decreased, along with appearance of coagulation factor V inhibitor (FVI). He did not have antiphospholipid syndrome or malignancy. He was diagnosed as having acquired FVI caused by DEM. Steroid pulse therapy was effective. There have been 74 reported cases of AFVI induced by drug treatment, but none after treatment with DEM.