Livedoid vasculopathy and popliteal artery occlusion in a patient with protein S deficiency

Livedoid vasculopathy (LV) is a chronic disease with recurrent reticularis and ulcers, mainly affecting the feet and lower legs. The pathogenesis of LV has not been yet thoroughly understood, but thrombosis is thought to play a major role because fibrin deposition within both the wall and lumen of affected vessels is pathologically detected. A 68-year-old woman first presented to our hospital in 2004 with a 6-year history of a reticular rash and ulceration on the lower legs. Screening tests for vasculitis and collagen disease were mostly normal, leading to diagnosis of LV. After failed treatment with steroid and aspirin, she was started on warfarin, to which she had a favorable response. However, she had to be admitted to the hospital because complication of swelling and infection in her left lower leg in 2004 + 10. Contrast-enhanced computed tomography showed thrombosis in the left popliteal artery. Screening tests for thrombotic tendency revealed that protein S activity was low (27%) although total protein S antigen was within normal range (73%). Analysis of protein S-alpha gene revealed 155 Lys>Glu mutation in exon VI, which was reported in 1994 and named as protein S Tokushima. Thus, we conclude that protein S deficiency could contribute to LV.