Thrombotic Microangiopathy in the Setting of Colorectal Cancer: A Therapeutic Challenge with a Bad Prognosis.

While most cases of thrombotic microangiopathic hemolytic anemias are idiopathic, some can occur in the setting of a malignancy. Differentiating both conditions is crucial to initiate the appropriate treatment. In this case report and literature review, we discuss the occurrence of a thrombotic microangiopathy in a 61-year-old male patient with a treatment-refractory metastatic colorectal cancer invading his bone marrow. Plasmapheresis does not constitute the mainstay of treatment in this setting, as targeting the primary disease is the ultimate management. Treating the condition of our patient has been challenging as multiple lines of treatments of his primary disease had been exhausted. The discrepancy in KRAs status obtained between PCR and later NGS offered a new treatment line with Cetuximab. In this article, we will discuss the different factors that differentiate between idiopathic and cancer-induced microangiopathy. We will emphasize on the fact that the treatment of the primary disease constitutes the most important step in the treatment of cancer-induced thrombotic microangiopathy. We will also raise several explanations to target the disagreement in KRAS status obtained by the different technical modalities.