[Difficulties in the diagnosis of familial hemophagocytic lymphohistiocytosis].

Familial hemophagocytic lymphohistiocytosis (FHL) is characterized by proliferation and non-malignant activation of histiocytes and T lymphocytes in the reticuloendothelial system. Diagnostic guidelines include fever, splenomegaly, cytopenia, hypertriglyceridemia and/or hypofibrinogenemia with hemophagocytosis in the bone marrow, spleen or lymph nodes. In many patients diagnosis is difficult due to the lack of diagnostic criteria, hemophagocytosis, variability of clinical presentation, spontaneous improvement and the absence of a specific marker of the disease. When there is strong clinical suspicion of FHL, chemotherapy and immunosuppressor treatment should be started early to achieve complete cure and should be followed by hematopoietic stem cell transplantation. We present the case of a 2-month-old girl who presented fever, anemia and thrombocytopenia, enlarged liver and spleen, hyperferritinemia, hypertriglyceridemia, and hypertransaminasemia without the finding of hemophagocytosis in bone marrow. Two of the girl's relatives had died of fulminant hepatic failure of unknown etiology. The patient improved spontaneously but presented reactivation of the disease 3 weeks later and died after splenic biopsy.