Experience with Hemophagocytic Lymphohistiocytosis at a Single Institution.

Hemophagocytic lymphohistiocytosis/macrophage activation syndrome (HLH/MAS), whether primary or secondary, is a serious and potentially life- threatening histiocytic disorder and generally fatal without immune modulating chemotherapy. This study aimed to define the clinical spectrum and treatment outcome in Korean children.

Patients who were diagnosed with HLH/MAS at Asan Medical Center between October 1997 and April 2009 were identified and charts were reviewed.

Twenty-six patients (16 male, 10 female) were evaluated during 13 - year period. Median age at diagnosis was 29.5 months (range: 0 - 180 months). Twelve patients had HLH secondary to underlying disorders, including viral infection, autoimmune disease. Epstein-Barr virus (EBV) - associated HLH was present in 9 patients, 1 of whom died, while 4 of 17 non-EBV associated patients died. Initial treatment with intravenous immunoglobulin (IVIG) was given to 9 patients and they had no response to IVIG. Eventually, all the patients except two underwent full protocol therapy (HLH 1994/2004) and the 2 patients died of rapid disease progression with delayed diagnosis. Seven patients revealed disease reactivation, median 3 months from HLH protocol therapy, and further treatment using the same regimen induced second remission of short duration. Seven patients (26.9%) had evidence of central nervous system disease at the time of diagnosis and neurological symptoms consisted of seizure, irritability, vomiting. Five of them are long-term survivors including one who received allogeneic stem cell transplantation (SCT) and all 5 patients show normal neurological function after treatment. The familial form of HLH was identified in 3 patients and all received allogeneic SCT from unrelated donor in second remission. They are still alive without relapse. At a median follow-up of 17.5 months, the estimated one-year overall survival rate was 82.8 ± 7.9 %.

Treatment outcomes using HLH 1994/2004 protocols in Korean children have become comparable to those reported in an international collaborative study. And allogeneic SCT represents a curative treatment for familial form of HLH. Further studies are required to more precisely define clinical spectrum and treatment outcome.

No relevant conflicts of interest to declare.