C0168 The APCR ratio is differently influenced by warfarin therapy when different assays are used

the onset of classical varicella zoster infectionwith an extensive purpuric rash covering both legs. The patient had leukocytosis with neutrophilia, thrombocytopenia (76.000X109/L), altered coagulation tests and DDimerN2000 ng/ml). Initially it was treated with broad-spectrum antibiotics, IV acyclovir and free fresh plasma (FFP). The lesions spread rapidly towards the abdomen forming painful ecchymotic plaques with necrotic-bullous areas and hypovolemic shock 48 hours after. Laboratory tests showed a disseminated intravascular coagulation (actived partial thromboplastinN180”, IQb10%, fibrinogenb0.5 g/l, D-Dimer 9000 ng/ml) and Hb 7.2 g/dl. She was treated with enoxaparin (1 mg/kg/12 h) and FFP (15–20 ml/kg). Subsequent result confirmed the diagnosis, as she had a free protein S (PS) of 6.1 IU/dl, total PS antigen 26.4 IU/dl and positive anti-PS antibodies (IgG 138 U/ml and IgM 28 IU/ml). After 22 days treatment, the girl had functional PS levels of 34%,with skin necrosis extended to 25% of the body surface. The patient required periodic surgery to remove necrotic tissue and skin graft. After 2 months of onset of treatment, the rate of PS reached normal levels (144%), with negative anti-PS antibodies. The patient required rehabilitation therapy to improve joint mobility and muscle mass in the lower extremities. At present, the functional recovery is complete. Comment: Purpura Fulminans secondary to varicella infection, mediated by antibodies against PS, is a rare entity. The severity and the extent of it will depend on the speed of the diagnosis and therapy. The clinical picture of PF is so characteristic that it is by itself diagnostic and should be suspected in any child with a rapidly progressive purpura and antecedents of chickenpox.FFP performance in terms of increased levels of PS, can be decreased by the presence of anti-PS antibodies. Treatment should be maintained until the disappearance of the anti-PS antibodies.