Microangiopathic haemolytic anaemia in metastasizing malignant tumours is not associated with a severe deficiency of the von Willebrand factor-cleaving protease

Complete deficiency of von Willebrand factor-cleaving protease (VWF-cp) has recently been identified as a pathogenetically important factor for thromb otic thrombocytopenic purpura (TTP). Microangiopathic haemolytic anaemia (M AHA) with thrombocytopenia in patients with metastasizing neoplasms is clin ically similar to TTP, however, the pathogenesis of the condition is unclea r. Partial deficiency of VWF-cp in metastasizing malignancy has recently be en reported in patients without MAHA, Our study shows normal or subnormal V WF-cp activity in four patients with metastasizing neoplasia-associated MAH A but, in contrast to classical TTP, no complete deficiency of VWF-cp despi te the full clinical picture of MAHA.