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Acute cancer-associated pulmonary embolism with chemotherapy-induced severe thrombocytopenia — ABIM Board MCQ

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HardVenous ThromboembolismAcute cancer-associated pulmonary embolism with chemotherapy-induced severe thrombocytopeniaABIM Board

A 48-year-old man with relapsed diffuse large B-cell lymphoma develops pleuritic chest pain and dyspnea 8 days after receiving myelosuppressive chemotherapy. CT pulmonary angiography shows a saddle pulmonary embolus extending into both lobar pulmonary arteries. The right ventricular-to-left ventricular diameter ratio is 1.2, and serum troponin is elevated. His blood pressure is 124/76 mm Hg, pulse is 112/min, oxygen saturation is 93% on 2 L/min of oxygen, and lactate is 1.4 mmol/L. His platelet count is 28,000/µL and is expected to remain between 25,000 and 40,000/µL for the next 5 days. Hemoglobin, fibrinogen, PT, and aPTT are normal. He has no active bleeding, severe kidney dysfunction, or planned invasive procedure. Platelet transfusions can reliably maintain a selected threshold. Which of the following is the most appropriate initial anticoagulation strategy?

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Correct answer: B — Full-dose low-molecular-weight heparin with platelet transfusions to maintain 40,000–50,000/µL

This patient has acute cancer-associated thrombosis with severe chemotherapy-induced thrombocytopenia. Although he is normotensive, the central clot location, large embolic burden, right ventricular dilation, and myocardial injury identify a high risk of early thrombus progression or clinical deterioration. In acute, high-progression-risk VTE with platelets below 50,000/µL, full-dose LMWH or UFH with platelet transfusion support to maintain approximately 40,000–50,000/µL is suggested. LMWH is an appropriate parenteral choice here because kidney function is preserved and rapid procedural interruption is not anticipated. Half-dose LMWH is attractive at a platelet count of 28,000/µL, but dose modification without transfusion support is better suited to lower-risk events, such as distal DVT, catheter-associated thrombosis, or isolated subsegmental PE. Apixaban is used for cancer-associated VTE in selected patients, but patients with severe thrombocytopenia were inadequately represented in pivotal DOAC evidence; an adjustable parenteral regimen is preferred during this phase. Complete interruption would expose this patient to substantial early recurrence or progression risk and is generally reserved for very low platelet counts, active bleeding, or lower-risk thrombosis. An inferior vena cava filter does not treat the existing PE and is reserved for an absolute inability to administer anticoagulation; transfusion-supported anticoagulation is feasible here.

Reference: Evidence-Based Minireview: Full dose, modified dose, or no anticoagulation for patients with cancer and acute VTE and thrombocytopenia (December 9, 2022) — https://pubmed.ncbi.nlm.nih.gov/36485075/ Anticoagulant therapy in patients with cancer and thrombocytopenia (2025) — https://pubmed.ncbi.nlm.nih.gov/41099929/