A 58-year-old man with newly diagnosed pancreatic cancer presents to the emergency department with acute dyspnea and chest pain. His vital signs show BP 95/60, HR 110, RR 28. D-dimer is markedly elevated at 8.5 μg/mL (normal <0.5). CT pulmonary angiography confirms bilateral pulmonary emboli. His PT is 18 seconds (control 12), aPTT is 52 seconds (control 32), platelet count is 65,000/μL, and fibrinogen is 150 mg/dL (normal 200–400). What is the most likely underlying coagulation disorder?

Explanation

## Pathophysiology of Cancer-Associated DIC This patient presents with the classic pentad of DIC: thrombosis (PE), bleeding tendency, thrombocytopenia, prolonged coagulation times, and hypofibrinogenemia. ### Diagnostic Criteria for DIC **Key Point:** DIC is a consumptive coagulopathy triggered by release of tissue factor (TF) from malignant cells, leading to simultaneous activation of coagulation and fibrinolysis. ```mermaid flowchart TD A[Pancreatic cancer cells]:::outcome --> B[Release of Tissue Factor]:::outcome B --> C[Activation of extrinsic pathway]:::action C --> D[Thrombin generation]:::action D --> E[Fibrin deposition in microvasculature]:::action E --> F[PE, DVT, microvascular thrombosis]:::urgent D --> G[Platelet consumption]:::action D --> H[Fibrinogen consumption]:::action D --> I[Activation of fibrinolysis]:::action G --> J[Thrombocytopenia]:::outcome H --> K[Hypofibrinogenemia]:::outcome I --> L[Elevated D-dimer, FDP]:::outcome ``` ### Laboratory Findings in DIC | Parameter | Finding | Mechanism | |-----------|---------|----------| | PT | ↑ (18 sec) | Consumption of factors II, V, VII, X | | aPTT | ↑ (52 sec) | Consumption of factors II, V, VIII, IX, X, XI, XII | | Fibrinogen | ↓ (150 mg/dL) | Consumption by thrombin + fibrinolysis | | Platelet count | ↓ (65,000/μL) | Consumption in microthrombi | | D-dimer | ↑↑ (8.5 μg/mL) | Fibrinolysis of deposited fibrin | | Schistocytes | Present | Mechanical hemolysis from fibrin strands | | Prothrombin time | ↑ | Factor consumption | **High-Yield:** The **combination of prolonged PT + aPTT + low fibrinogen + low platelets + high D-dimer** is pathognomonic for DIC. No other single disorder produces this pentad. **Clinical Pearl:** Pancreatic cancer is one of the most common malignancies associated with DIC (~10% of cases), followed by acute promyelocytic leukemia (APL), lung cancer, and gastric cancer. The malignant cells express tissue factor on their surface, directly triggering the coagulation cascade. **Warning:** Do not confuse DIC with simple vitamin K deficiency or liver disease. In vitamin K deficiency, fibrinogen is normal and platelets are normal; in DIC, both are consumed.