Cancer-related thrombotic microangiopathy secondary to Von Willebrand factor-cleaving protease deficiency.

Cancer-related thrombotic microangiopathy (TM) is a serious complication with a short-term life-threatening prognosis. This complication shares certain similarities with thrombotic thrombocytopenic purpura and hemolytic uremic syndrome, both characterized by circulating platelet aggregates containing ultralarge multimers of Von Willebrand factor (VWF). We report a case of cancer-related thrombotic microangiopathy secondary to disseminated metastatic cancer with undetectable serum Von Willebrand factor-cleaving protease activity and no evidence of serum inhibitory antibody. A concomitant decrease of Ca 19-9 level and hemolysis was observed during chemotherapy, in parallel with normalization of Von Willebrand factor-cleaving protease activity. The role of ultralarge multimers of Von Willebrand factor in platelet aggregation in the context of metastatic disease is discussed with respect to our findings in this case of cancer-related thrombotic microangiopathy.