Recurrent macrophage activation syndrome associated with heterozygous perforin W374X gene mutation in a child with systemic juvenile idiopathic arthritis.

Background: Recurrent macrophage activation syndrome (MAS) is rarely reported.

Aim: To describe recurrent MAS in a 2.5-year-old girl with systemic juvenile idiopathic arthritis and heterozygous perforin mutation, which may have a role in the patient's first recurrence despite use of the HLH-2004 treatment protocol.

Observations: In the presented case, MAS was initially controlled after the addition of etoposide to the treatment regimen. However, recurrence occurred 6.5 months after cessation of the HLH-2004 protocol. Subsequent recurrences may have occurred because of the family's noncompliance with treatment.

Conclusions: The patient's extremely high serum ferritin level (267,054 ng/mL) and the recurrent course of MAS may have been because of the coexistence of juvenile idiopathic arthritis and heterozygous perforin W374X mutation. We suggest to search for mutations in HLH genes in recurrent MAS cases.