[An atypical skin rash in a setting of antiphospholipid syndrome].

Antiphospholipid syndrome (APS) is characterised by arterial or venous thrombosis combined with the presence of specific antibodies known as antiphospholipids. It is commonly associated with cutaneous signs. Herein we report a case of atypical cutaneous eruption occurring during the course of APS and we discuss the possible mechanism. A 45-year-old woman consulted twice within six months for an erythematosus papular eruption around the neckline. She was being followed-up for antiphospholipid syndrome treated with fluindione (Préviscan®), and her International Normalized Ratio (INR) was consistent with the prescribed anticoagulation target. Blood tests confirmed the presence of anticardiolipin and antiphospholipid antibodies, but no laboratory evidence of lupus was seen. Histopathological examination of a skin biopsy demonstrated the presence within the vascular lumen of a weakly eosinophilic anhistic substance positive for PAS stain. The patient was given acetone salicylic acid (Kardégic®) combined with fluindione, and four years later, she had presented no relapses. Despite a clinically evocative appearance, the diagnosis of lupus tumidus was ruled out in our patient by histopathological features, and associated systemic lupus erythematosus was repeatedly refuted on the basis of clinical and laboratory data. We suggest that the specific histological images of intraluminal deposits within the dermal vessels seen in this patient, although not typical of thrombosis, are associated with APS. The clinical remission seen from the start of antiplatelet treatment could be due to the action of these drugs against the obstruction of small-calibre dermal vessels.