Case Presentation: Case 1: A 38-year-old woman with no past medical history presented to the hospital with four days of fatigue, myalgias, and productive cough. On admission, she was febrile to 103 F, had a heart rate of 130 with ECG showing sinus tachycardia, saturating 95% on two liters of nasal cannula oxygen. Initial workup was notable for complete blood count and high-sensitivity troponin within normal limits, and chest radiograph showing bilateral airspace opacities consistent with multifocal pneumonia. A respiratory viral swab was positive for adenovirus. Tachycardia and hypoxemia persisted. A D-Dimer was elevated to 731 ng/mL; computed tomography pulmonary angiography (CT-PA) revealed a left upper lobe segmental pulmonary embolism (PE), and transthoracic echocardiogram (TTE) was without evidence of right heart strain. Therapeutic anticoagulation was initiated with apixaban and she was discharged home.Case 2: A 44-year-old woman with a history of mild intermittent asthma presented to the hospital with ten days of shortness of breath and cough. On admission, she was afebrile, with a heart rate in the 130s with sinus tachycardia on ECG, saturating 98% on six liters of nasal cannula oxygen. Complete blood count and high-sensitivity troponin were within normal limits, and D-dimer was elevated to 2224 ng/mL. CT-PA on admission (limited by mixing artifact) showed no definite PE; bilateral consolidative opacities were present, suggestive of multifocal pneumonia. PCR testing for COVID-19, influenza A, and influenza B and urine antigen testing for streptococcus pneumoniae and legionella were negative. Despite empiric treatment for community-acquired pneumonia and asthma with antibiotics, bronchodilators, and glucocorticoids, her hypoxemia persisted. A respiratory viral panel returned positive for adenovirus. Repeat CT-PA showed segmental and subsegmental PEs without right heart strain on TTE. She was started on apixaban and discharged home several days later.
Discussion: The potential association between adenovirus infection and thrombotic events is not well understood and prior case reports are limited (1). Some prior cases suggest an increased risk of venous thromboembolism (VTE) among recipients of adenovirus-based vaccine vectors against COVID-19 (2). Many of these cases have been in the context of vaccine-induced thrombocytopenic purpura (VITT), a thrombotic microangiopathy associated with adenovirus vectors related to autoantibody formation against platelet factor 4 (3-5). Previous work has postulated a complex interplay between adenovirus and activation of endothelial cells and components of both primary and secondary hemostasis pathways, providing a theoretical mechanism for adenovirus-associated VTE, even in the absence of thrombocytopenia (6).
Conclusions: Adenovirus is a common respiratory virus known to have interactions with platelets, clotting factors, and vascular endothelium. Though adenovirus-based vaccine vectors have been linked to cases of thromboembolism, fewer cases have been reported in the literature of VTE related to primary adenovirus pneumonia. Clinicians should remain vigilant for the possibility of thromboembolic complications including pulmonary embolism in the context of adenovirus infection.