Temporal Association between Hampton's Hump Pulmonary Embolism and First-Dose ChAdOx1 nCov-19 Vaccine in a Patient with Activated Protein C Resistance.

A 58-year-old man presented to his practitioner with right-sided pleuritic chest pain, dyspnea, and fatigue 18 days following the first dose of the ChAdOx1 nCov-19 vaccine. Chest radiography showed a basal wedge-shaped consolidation indicative of a Hampton’s hump in the right lower lobe, which was confirmed by subsequent computed tomography pulmonary angiography. The major laboratory abnormalities were a markedly elevated D-dimer level of 7.53 µg/mL (normal range < 0.5 µg/mL), a CRP level of 62.8 mg/L (normal range < 5 mg/L), and a previously unknown activated protein C resistance of 1.3 (normal range ≥ 1.8). Genetic analysis identified the patient to be heterozygous for the FVLeiden mutation. Neither other errors of hemostasis nor antibodies against platelet factor 4-polyanion complexes could be observed. Moreover, we failed to demonstrate Severe Acute Respiratory Syndrome Coronavirus-2 infection. The patient fully recovered with no sequelae but is being continued on long-term anticoagulation given his risk of recurrent venous thromboembolism. Here we report on the temporal association between the first dose of the ChAdOx1 nCov-19 vaccine and extensive pulmonary embolism in an otherwise healthy patient with activated protein C resistance, however, further investigation is needed to prove causality.