Familial haemophagocytic lymphohistiocytosis: two case reports (original) (raw)

Abstract

Haemophagocytic lymphohistiocytosis (HLH) is a life threatening inflammatory syndrome, which presents a highly stimulated but ineffective immune response with severe hypercytokinaemia. HLH, primary or secondary, is characterised by prolonged fever and hepatosplenomegaly associated with pancytopenia, hypertriglyceridaemia and hypofibrinogenaemia. However, the hallmark of HLH is impaired or absent function of natural killer cells and cytotoxic T lymphocytes. HLH presents major diagnostic difficulties, since it may have an incomplete and/or late onset and with many conditions leading to the same clinical picture. When untreated, it is fatal in all primary cases and in a high percentage of acquired cases. Awareness of the clinical picture and diagnostic criteria is thus important to start life saving treatment. We describe two cases of primary HLH, with significant differences in their clinical presentation and evolution. Background Haemophagocytic lymphohistiocytosis (HLH) is a severe hyperinflammatory condition, with uncontrolled proliferation of activated lymphocytes and histiocytes secreting high amounts of inflammatory cytokines. However, this is an ineffective immune response, since there is an impaired function of lymphocytes.1 HLH occurs in association with a variety of conditions (genetic or acquired) leading to the same inflammatory phenotype. Whether primary or secondary, it is characterised by prolonged fever and hepatosplenomegaly associated with pancytopenia, hypertriglyceridaemia and hypofibrinogenaemia.2 Increased concentrations of cytokines and impaired or absent function of natural killer cells (NK) and cytotoxic T lymphocytes are biological markers of HLH. The non--specific signs and symptoms, with multiorgan involvement and sometimes with an incomplete and/or late onset, make HLH a disease with major diagnostic and therapeutic difficulties. Diagnostic and therapeutic guidelines, based on common clinical, laboratory and histopathological findings, were presented by the HLH Study Group of the Histiocyte Society (revised in

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