A rare syndrome in the differential diagnosis of hepatosplenomegaly and pancytopenia: report of identical twins with Griscelli disease.

White, identical twin boys aged 3 months were referred to our centre with persisting fever, mouth ulcers, hepatosplenomegaly, pancytopenia and failure to thrive. The parents were first cousins and there was a history of a sibling with similar manifestations who had died. The infants had silvery-grey hair and pigment clumps on the hair shafts, and skin biopsy showed accumulation of melanocytes on melanosomes. Bone marrow revealed hypercellularity and haemophagocytosis. HLH-94 chemotherapy (initial therapy with daily dexamethasone and etoposide, maintenance with dexamethasone pulses, etoposide and cyclosporin A) was started. Though partial haematological remission was achieved, one of the boys died on the 34th day following aspiration pneumonia. No pathogen could be identified. The second boy responded to therapy but had a haematological relapse and died 68 days after first being admitted. Genetic study revealed a 5 bp deletion in the RAB27A gene (510 del AAGCC in exon 5). Transient haematological remission can be achieved with chemotherapy but allogeneic bone marrow transplantation is the only curative therapy in Griscelli disease, as in other familial haemophagocytic syndromes. Identification of the mutation also provides an opportunity for prenatal diagnosis.