In children with bi- or pancytopenia, hemophagocytosis is known as life-threatening hemophagocytic lymphohistiocytosis (HLH). The purpose of the study is to find out whether adult patients with bicytopenia or pancytopenia fulfilling the clinical HLH criteria used in children reflect life-threatening hemophagocytosis and whether hemophagocytosis is associated with responsiveness to recombinant human granulocyte colony-stimulation factor (rhG-CSF) or not.