Relapsing catastrophic antiphospholipid antibody syndrome: a mimic for thrombotic thrombocytopenic purpura?

The catastrophic antiphospholipid antibody syndrome (CAPS) is an uncommon disorder characterized by widespread micro- and macrovascular changes due to intravascular thrombosis. This complication of the antiphospholipid antibody syndrome is often fatal and recurrences are very rare. The differential diagnosis of CAPS includes thrombotic thrombocytopenic purpura (TTP) and this distinction may be difficult, but essential, for appropriate therapy. Plasmapheresis is effective in both conditions, but anticoagulation, a mainstay in the treatment of CAPS, could be disastrous in TTP. We present the case of an elderly woman who survived two episodes of CAPS four years apart and whose clinical findings were also suggestive of TTP. The characteristics of TTP and CAPS are compared and the importance of accurate diagnosis is emphasized.