Thrombocytopenia and hemolytic anemia in a patient with mixed connective tissue disease due to thrombotic thrombocytopenic purpura.

A 33-year-old woman with mixed connective tissue disease (MCTD) presented with headache, fever, thrombocytopenia, hemolytic anemia, and renal involvement due to thrombotic thrombocytopenic purpura (TTP). She did not improve after treatment with prednisolone, fresh frozen plasma, antiplatelet agents, and prostacyclin, but a trial with vincristine resulted in a longlasting complete remission. TTP in autoimmune diseases probably results from immune mediated vasculopathy, which was demonstrated in our patient using nailfold capillary microscopy. Though TTP has many clinical and laboratory features in common with active MCTD, recognition of differences between the 2 conditions, i.e., microangiopathic hemolytic anemia and a negative Coombs' test in the former, is important because treatment in the 2 conditions differs.