Secondary hemophagocytic lymphohistiocytosis possibly induced by interferon beta-1a therapy.

A 57-year old woman with a history of multiple sclerosis, treated with interferon beta-1a in the last 5 months, was referred for hyperpyrexia (>40°C) that persisted for 15 days. At admission, there was elevation of transaminases, anemia (hemoglobin 8.9 g/dL), thrombocytopenia (platelet 135,000/mm3), and hypofibrinogenemia (fibrinogen 1.26 g/L). C-reactive protein was 10.7 mg/dL, lactate dehydrogenase 1270 U/L and ferritin 2380 ng/ mL, with hepatosplenomegaly and linfoadenomegaly. Hemophagocytic lymphohistiocytosis induced by direct stimulation of macrophages by interferon (IFN) was suspected. IFN was withdrawn as only measure and onemonth later signs and symptoms disappeared, with complete normalization of laboratory examinations