[A Case of Thrombotic Thrombocytopenic Purpura in a Patient Undergoing FOLFOX6 plus Panitumumab Therapy for Unresectable Recurrent Rectal Cancer with a Rapidly Progressive Course].

A 71-year-old male patient began FOLFOX6 plus panitumumab treatment for unresectable recurrent rectal cancer. He developed thrombocytopenia after 2 courses of treatment and therefore a platelet transfusion was performed. The day after transfusion, the patient developed jaundice and hematuria. His lactate dehydrogenase levels had increased and a peripheral blood smear review revealed the presence of schistocytes. Anti-ADAMTS13 antibodies were present, and there was a reduction in ADAMTS13 activity. The patient was diagnosed with thrombotic thrombocytopenic purpura and treated with a plasma exchange. The day after the plasma exchange, his clinical condition rapidly worsened and he died. Thrombocytopenia due to chemotherapy often appears as myelosuppression. If conditions such as jaundice, indirect bilirubinemia, or hematuria appear during the course of chemotherapy, this condition must be considered as a differential diagnosis.