Hemophagocytic Lymphohistiocytosis - Diagnostic and Therapeutic Dilemma

Overview

Syndrome of hemophagocytic lymphohistiocytosis (HLH) is characterized by uncontrolled proliferation of Tlymphocytes and macrophages. HLH develops in patients with primary or secondary immunodeficiency. Overproductionof cytokines plays a major role in the tissue damage and in the development of typical clinical andlaboratory features - persistent fever, hepatosplenomegaly, peripheral blood cytopenia, hypertriglyceridemia,hypofibrinogenemia and bonemarrow hemophagocytosis.Two forms ofHLHexist: primaryHLH - a heterogenousgroup of rare genetic disorders and a secondary form, associated with systemic infections, malignancies or systemicautoimmune diseases. HLH is a life-threatening acute illness frequently progressing into the multiorgan failureand death. Establishment of diagnosis and the appropriate choice of therapy are often difficult. Both forms ofHLHrespond well to the immunosuppressive therapy. Stem cell transplantation offers the only curative treatmentstrategy for children with the primary HLH. Diagnostic and therapeutic dilemma is demonstrated on case-reportsof patients suffering from familial hemophagocytic lymhohistiocytosis, Chediak-Higashi syndrome, fatal infectiousmononucleosis, visceral leishmaniasis, large cell anaplastic lymphoma, secondary malignant histiocytosis andmacrophage activation syndrome associated with juvenile idiopathic arthritis. Awarness of differential diagnosisof HLH, application of modern diagnostic methods and an early initiation of the efficient treatment improve theprognosis of these unfavourable disorders.

Key words:
hemophagocytic lymphohistiocytosis, immunodeficiency, infection, macrophage activation syndrome,stem-cell transplantation