Case Description
The patient presented due to new onset chest pain and persistent left
leg pain and swelling after a hyperextension injury of the knee 4 days
prior forced him to be immobilized. He was tachycardic on presentation
with otherwise normal vital signs. Physical examination was significant
for left lower extremity swelling from knee to ankle with limited range
of motion secondary to swelling and pain. Although he had erythematous
skin changes on his ankle, he had palpable pulses and normal capillary
refill. He had a normal cardiopulmonary examination. His known trauma,
immobilization, and obese body mass index (34 kg/m2)
were considered possible etiologies to provoke the thromboses, and his
family history was unremarkable for thrombosis. Doppler ultrasonography
showed extensive occlusive thrombosis of left femoral and popliteal
veins. May-Thurner syndrome was ruled-out given the limited proximal
extent of the left leg thrombus and venous anatomy. Chest computed
tomography angiography demonstrated saddle PE with thrombus extending
into the left and right pulmonary arteries (Fig. 1). Echocardiogram
showed no evidence of right ventricular systolic failure or dilation,
and brain natriuretic peptide and troponins were normal. He was
hemodynamically stable and his PE was categorized as low-risk. No
procedural interventions were indicated.
He was initially started on therapeutic anticoagulation with intravenous
unfractionated heparin titrated to achieve anti-Xa level between 0.3-0.7
units/mL. He required oxygen support via nasal cannula but was weaned to
room air within 48 hours of presentation. He was transitioned to
enoxaparin at pediatric therapeutic starting dose of 1 mg/kg and
titrated to achieve an anti-Xa level between 0.5-1 units/mL. Upon
discharge, he still had swelling and pain of the lower extremity but was
able to ambulate on crutches.
Despite his known preceding trauma, immobility, and obesity, he
underwent laboratory evaluations for underlying thrombophilia due to the
degree of thrombosis on presentation. Results were significant for
heterozygous mutations of both FVL and PT-G20210A, positive anti-beta 2
glycoprotein I (aβ2GPI) IgG antibody, and lupus anticoagulant (LA;
positive Staclot, negative diluted Russell viper venom time); his aβ2GPI
IgM and anti-cardiolipin (aCL) IgM/IgG antibodies were all negative. He
was discharged home on therapeutic enoxaparin due to concern for reduced
efficacy of direct oral anticoagulants in treatment of patients with
APS. Repeat testing at 3 months re-demonstrated the same findings for
his antiphospholipid antibody profile, which was consistent with a
diagnosis of APS based on the Sapporo criteria.Repeat Doppler
ultrasonography at 3 months demonstrated improvement but residual
non-occlusive thrombosis of left femoral and popliteal veins and
therapeutic enoxaparin was continued.