RESUMO
Hemophagocytic lymphohistiocytosis [HLH] 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 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 familial hemophagocytic lymphohistiocytosis [FHL], chemotherapy and immunosuppressor treatment should be started early to achieve complete cure and should be followed by hematopoietic stem cell transplantation. We present a case of a 13 months old boy who presented with fever, anemia and thrombocytopenia, enlarged liver and spleen, hyperferritinemia, hypertriglyceridemia and hypertransaminasemia without the finding of hemophagocytosis in the bone marrow. The patient improved spontaneously but presented with reactivation of the disease six weeks later and died after few weeks