S3939 Disseminated Intravascular Coagulation: A Rare Hematologic Complication of Newly Diagnosed Colon Cancer

Introduction: Disseminated intravascular coagulation (DIC) involves simultaneous bleeding and thrombosis due to activation of clotting and fibrinolytic pathways. While typically associated with trauma, sepsis, or hematologic malignancies, solid tumor-associated DIC is rare, particularly as the initial presentation of colorectal cancer. Case Description/Methods: A 69-year-old man presented with hematochezia and coffee-ground emesis. One month prior, he was admitted for right-sided weakness and rectal bleeding, diagnosed with multifocal ischemic stroke, carotid stenosis, bilateral deep vein thrombosis, and a 5 cm ulcerated ascending colon mass. Interventions during that admission included carotid endarterectomy, thrombectomy, inferior vena cava filter placement, and biopsy-confirmed adenocarcinoma. Imaging revealed thoracolumbar metastases. He was discharged on rivaroxaban. On readmission, he was tachycardic and hypotensive. Labs showed severe anemia (Hb 5.6 g/dL), thrombocytopenia (137 × 10³/µL), and coagulopathy (international normalized ratio [INR] 13, aPTT 36.4). He received packed red blood cells, PCC, and vitamin K; anticoagulants were held. Magnetic resonance imaging confirmed vertebral/sacral metastases, and CEA was elevated (11,743 ng/mL). Platelets dropped to 18 × 10³/µL, and he developed livedo reticularis (microvascular occlusion) and a small PE. Hemolysis labs revealed elevated LDH (2235 U/L), undetectable haptoglobin, and hyperbilirubinemia. DIC was confirmed: fibrinogen <60 mg/dL, FDP >20 µg/mL, and persistent INR elevation (3.65). Schistocytes without blasts were seen on smear. The findings supported DIC secondary to metastatic adenocarcinoma, exacerbated by liver dysfunction and residual rivaroxaban. Discussion: DIC in solid tumors is rare (<15% of metastatic cases) and carries a poor prognosis. Tumor-expressed tissue factor activates coagulation via factor VII. This case illustrates colorectal cancer presenting as DIC—only 13 similar reports exist. Concurrent bleeding (GI hemorrhage) and thrombosis (stroke, PE) complicated management amid severe coagulopathy (INR 13, platelets 18 × 10³/µL) and microvascular occlusion. Balancing anticoagulation with transfusion support was critical during rapid multiorgan failure. Chemotherapy was not pursued given the grave prognosis of malignancy-associated DIC. This underscores DIC as a potential first sign of occult malignancy, necessitating clinical vigilance, individualized anticoagulation, and timely goals-of-care discussions.