Systemic-onset juvenile chronic arthritis and bone marrow hypoplasia.

A two- and-a-half-year-old girls with systemic-onset JCA developed pancytopaenia 21 days after her illness began. Bone marrow examination revealed hypoplasia, with no evidence of erythrophagocytosis. Two weeks later peripheral blood specimens showed evidence of bone marrow regeneration. No definite cause for the hypoplasia was found subsequently. Persistent haematological abnormalities after resolution of the hypoplasia included anaemia of chronic inflammation, leucocytosis and thrombocytosis. Unexplained bone marrow hypoplasia has not previously been described in systemic-onset JCA.