Syndromes de microangiopathie thrombotique et oncologie

[Breast cancer-related thrombotic microangiopathy: A review]

Thrombotic Microangiopathies (TM) have been described since the 1960s. They are characterized by presence of mechanical haemolytic anemia associated with peripheral thrombocytopenia. TM in cancer can be related to several causes, whose cancer himself: cancer-related microangiopathic haemolytic anaemia (MAHA). Incidence of cancer related MAHA remains unknown. Cancer-related MAHA are mainly observed in mucin-producer adenocarcinomas, such as gastric (half of reported cases) and breast cancer. We conducted a review of all original published cases of TM reported in breast cancer, and we specifically investigated BC-MAHA cases. A Medline search identified 158 MAHA cases including 118 BC-MAHA, and 40 drug-related MAHA. Most of BC-MAHA occur in disseminated cancers, mainly with medullar involvement, and/or bone metastasis. Patients typically suffer from poor general state, bone pain, and/or dyspnea. Laboratory abnormalities such as myelemia or erythromyelemia in peripheral blood are frequently observed. Incidence of coagulation disorders is increased, compared to other MAHA causes. BC-MAHA prognosis is dramatically poor. Treatments classically used in other MAHA causes, such as plasmapheresis or immunoglobulins, are inefficient. Urgent anti-neoplastic therapy may be the only effective treatment, associated to symptomatic therapies (transfusions, blood pressure control).

[Pulmonary tumor thrombotic microangiopathy]

Pulmonary tumor thrombotic microangiopathy syndrome is a rare clinicopathological entity in which tumor cell micro-emboli in the pulmonary microcirculation induced thrombotic microangiopathy. This can cause respiratory failure, and acute or sub-acute right heart failure. Histological features include micro tumor emboli in the small arteries and arterioles of the lung associated with thrombus formation and fibro-cellular and fibro-muscular intimal proliferation. The diagnosis is however extremely difficult to make before death. Thus, most of the observations reported are based on autopsy data. Very rare diagnostic observations made before death suggest the potential effectiveness of chemotherapy. Many details remain to be elucidated, interdisciplinary research is a priority with close collaboration between pathologists and clinicians to better understand this, often fatal, syndrome. It may be that the use of targeted therapies will improve the very poor prognosis allowing survival of several weeks or months after diagnosis.