[Secondary thrombotic microangiopathies]

Thrombotic microangiopathies (TMA) are termed secondary when associated to a specific context favouring their occurrence. They encompass mainly TMA associated with pregnancy, allogeneic hematopoietic stem cell transplantation, cancer, drugs, or HIV infection. Secondary TMA represent a heterogeneous group of diseases which clinical presentation largely depends on the associated context. It is therefore mandatory to recognize these conditions since they have a significant impact in TMA management and prognosis. A successful management still represents a challenge in secondary TMA. Significant progresses have been made in the understanding of pregnancy-associated TMA, allowing an improvement of prognosis; on the opposite, other forms of secondary TMA such as hematopoietic stem cell transplantation-associated TMA or TMA associated with chemotherapy remain of dismal prognosis. A better understanding of pathophysiology in these forms of TMA, in association with a more empirical approach through the use of new therapeutic agents that can also help in the understanding on new mechanisms a posteriori, should improve their prognosis. The preliminary encouraging results reported with complement blockers in this field could represent a convincing example.