Systemic juvenile idiopathic arthritis, Kikuchi's disease and haemophagocytic lymphohistiocytosis.

SIR, I read with interest the case report of a 1-yr-old girl with systemic juvenile idiopathic arthritis and Kikuchi’s disease, who later developed haemophagocytic lymphohistiocytosis (HLH), and its successful management [1]. Diagnostic criteria for HLH were published in 1991 [2]. The diagnosis of HLH requires the presence of all five criteria (fever >38.5 C for 7 or more days, palpable splenomegaly, cytopenia involving two or more cell lines, hypertriglyceridaemia or hypofibrinogenaemia and haemophagocytosis). The case reported by Ramanan et al. [1] satisfies the diagnostic criteria. In a recent study of 122 children with HLH enrolled from 11 countries, the rate of parental consanguinity was 24% and there was a positive family history in 49% of cases [3]. Ramanan et al. have not commented on the parental consanguinity and the family history of their patient. The prognosis of HLH has improved significantly since the advent of the HLH-94 protocol from the Histiocyte Society [3]. The protocol includes induction with dexamethasone and etoposide and intrathecal methotrexate in selected cases, followed by continuous treatment with cyclosporin along with pulses of dexamethasone and etoposide for 1 yr. However, haematopoietic cell transplantation appears to provide the best cure rate, of about 60% [4]. The 40-page HLH-94 protocol can be obtained from the Histiocytosis Association of America through their website (http://www.histio.org/society/protocols/trials-protocols.shtml). However, treating physicians and potential patients must be registered before the protocol can be released. Epstein–Barr virus and parvovirus B19 infections can be associated with both HLH and Kikuchi’s disease [5–7]. Ramanan et al. do not mention whether their patient was tested for these infections.