A 62-year-old woman with newly diagnosed adenocarcinoma of the lung completed her second cycle of chemotherapy 2 weeks ago. She presents to the emergency department with acute dyspnea, pleuritic chest pain, and unilateral leg swelling that developed over 2 days. Vital signs: BP 128/82 mmHg, HR 112 bpm, RR 22/min, SpO2 88% on room air, temperature 37.2°C. Laboratory values show: PT 12 seconds (normal 11-13.5), aPTT 28 seconds (normal 25-35), platelet count 185,000/μL, D-dimer 2500 ng/mL (normal <500). CT pulmonary angiography confirms bilateral pulmonary emboli with right lower lobe wedge-shaped infarction. Which of the following mechanisms most directly explains the hypercoagulable state underlying this patient's thromboembolism?
- A)Loss of protein C production by malignant hepatic infiltration
- B)Acquired antithrombin III deficiency from urinary losses
- C)Tissue factor and cancer procoagulant released by tumor cells activating the extrinsic pathwayGABARITO
- D)Prothrombin gene G20210A polymorphism increasing prothrombin levels
- E)Factor V Leiden mutation impairing activated protein C inactivation
Explicação
Cancer cells actively produce tissue factor (TF) and cancer procoagulant, which directly activate factor VII and trigger the extrinsic coagulation pathway. This is the primary mechanism of thrombosis in malignancy, particularly in adenocarcinomas like lung can... Ver explicação completa e trilha adaptativa →