Hemophagocytic lymphohistiocytosis (HLH) is a rare non-neoplastic, frequently fatal disease of childhood. It has been divided into two categories, familial and secondary, but the distinction between the forms is not easily made2. J.I. Henter, G. Elinder and A. Ost, FHL Study Group of the Histiocyte Society. Diagnostic guidelines for hemophagocytic lymphohistiocytosis. Semin Oncol 18 (1991), [...]