We evaluated clinical characteristics and prognosis for adult-onset Still's disease (AOSD) complicated by hemophagocytic lymphohistiocytosis (HLH). We retrospectively identified cases of AOSD with (n = 10) and without (n = 305) HLH complications. We reviewed their medical records, completed follow-up through outpatient clinic and telephone interviews, and analyzed their clinical symptoms, signs, laboratory test results, treatments, and prognosis. More AOSD patients with HLH developed hepatomegaly, bleeding, serositis, and neurologic symptoms than those without HLH, and they more commonly presented with leukopenia, thrombocytopenia, severe anemia, severe liver function abnormalities, decreased fibrinogen, elevated immunoglobulin, and bone marrow hemophagocytosis. The ten patients with AOSD complicated by HLH were treated with high-dose steroids or pulse steroid therapy, and eight of them also received cytotoxic drugs, while biological agents showed poor response. Follow-up results indicated that AOSD patients overall had good prognosis, while those with HLH showed worse prognosis, including higher relapse and readmission rates and increased mortality. In patients with AOSD, unexplained decreased blood cells, severe liver dysfunction, and/or hemophagocytosis in the bone marrow should be considered as signs of HLH complication. Patients with AOSD complicated by HLH have worse prognosis and higher relapse rates compared to AOSD patients without HLH complications. Thus, these patients should undergo frequent and careful follow-up.
Keywords: Adult-onset Still’s disease; Complication; Follow-up; Hemophagocytic lymphohistiocytosis.