Background: A 39-year-old woman with no relevant medical or family history was admitted to hospital with episodic fever, which persisted despite antibiotic therapy. Other notable findings at admission were splenomegaly, pancytopenia, hyponatremia, elevated levels of liver enzymes, hyperferritinemia and hypofibrinogenemia.
Investigations: Physical examination, laboratory tests, rheumatic marker serology, pathogen detection assays, complete blood counts, measurement of levels of ferritin, fibrinogen, triglycerides and soluble CD25, natural killer cell functional studies, PRF1 mutation analysis, renal biopsy, bone marrow biopsy, CT imaging of the chest and abdomen.
Diagnosis: Idiopathic, atypical hemophagocytic lymphohistiocytosis.
Management: Initial treatment with antibiotics was followed by immunosuppressive therapy (including intravenous immunoglobulin, ciclosporin, infliximab, corticosteroids and etoposide). Remission was achieved by treatment with the anti-CD52 monoclonal antibody, alemtuzumab, after which allogeneic stem-cell transplantation (with reduced-intensity conditioning treatment and graft-versus-host disease prophylaxis) resulted in a definitive cure.