Lupus anticoagulant and the skin. A longterm follow-up study of SLE patients with special reference to histopathological findings.

Skin manifestations were described in lupus anticoagulant (LA) positive and in LA negative SLE patients. Necrotic ulcers appearing at the beginning of the disease process characterized the 33 LA positive patients. Thirteen patients had a "peripheral vascular syndrome"; small leg ulcers of livedoid vasculitis type following deep venous thromboses, in 3 patients developing into pyoderma gangrenosum like ulcers and in 2 patients into pseudo-sarcoma Kaposi. The lesions were histologically characterized by capillary angiogenesis with extravasated red blood cells, sparse inflammatory cell infiltrates and microthromboses. Three patients had ulcers clinically and histologically resembling those seen in Degos' disease. Five patients had anetoderma showing elastic tissue depletion and microthromboses histologically. A different pattern of skin changes was seen in the LA negative patients. Our findings suggest that antiphospholipid antibodies play a pathogenetic role in the described skin manifestations of LA positive SLE patients.