Cancer-related thrombotic microangiopathy and disseminated intravascular coagulation in a patient with bone marrow carcinomatosis of unknown primary origin: A case report.

Background: Cancer-related thrombotic microangiopathy (CR-TMA) is a rare type of Coombs-negative hemolytic anemia, which is caused by malignancy and has a poor prognosis.

Case: A 76-year-old female was referred to our hospital due to Coombs-negative hemolytic anemia, which was causing fatigue and dyspnea on exertion, accompanied by schistocytosis. A bone marrow examination demonstrated bone marrow carcinomatosis, and the tumor cells were morphologically suspected to be signet-ring cell carcinoma cells. As we failed to find the primary tumor site before the patient died, she was diagnosed with CR-TMA due to bone marrow carcinomatosis of unknown primary origin. Thrombotic thrombocytopenic purpura (TTP) was rapidly ruled out based on her PLASMIC score. In addition, immunohistochemical staining of a clot section of the bone marrow and tumor marker data were useful for narrowing down the likely primary tumor site.

Conclusion: Although CR-TMA is an extremely rare phenomenon, clinicians who suspect CR-TMA should quickly rule out TTP and decide whether to provide appropriate chemotherapy or plan for palliative care.