Extensive Apparently Unprovoked Bilateral Proximal Deep Vein Thrombosis in a Young Woman with Antiphospholipid Antibody Positivity: A Case Report

Background

Deep vein thrombosis (DVT) in a young individual without an identifiable provoking factor warrants evaluation for acquired and inherited thrombotic risk factors. Antiphospholipid antibody (aPL) positivity may suggest antiphospholipid syndrome (APS), but diagnosis requires appropriate clinical and laboratory correlation and demonstration of persistent antibody positivity. Case Presentation: A 36-year-old woman presented with a few days of bilateral pedal edema, more prominent on the left side, associated with mild tenderness, erythema and warmth. There was no history of recent surgery, trauma, prolonged immobilization, pregnancy, oral contraceptive use or previous thrombotic event. Bilateral lower-limb venous Doppler demonstrated extensive thrombosis involving the proximal deep venous system, with complete thrombosis of the left femoral, common femoral and external iliac veins and associated great saphenous vein thrombosis. The right lower limb showed partial femoral vein thrombosis with thrombosis of the proximal great saphenous vein extending to the saphenofemoral junction. D-dimer was elevated at 5.2 µg/mL. Renal and hepatic functions were preserved. Thrombophilia evaluation revealed positive antinuclear antibody (ANA) by immunofluorescence at a titre of 1:320 with a spindle apparatus pattern, negative anti-double-stranded DNA antibodies and normal complement levels. Anticardiolipin IgM was 38 MPL and anti-β2-glycoprotein I IgM was 42 U/mL, with negative IgG antibodies. Homocysteine was normal and MTHFR A1298C was heterozygous. She was treated initially with therapeutic enoxaparin followed by apixaban.