Thrombocytopenia in systemic-onset juvenile chronic arthritis: report of two cases with unusual bone marrow features.

Two children with systemic-onset juvenile chronic arthritis (S-JCA) suffering from severe, symptomatic thrombocytopenia are reported. Case 1 is a 10-year-old girl who had fever, chronic polyarthritis and hepatosplenomegaly for 6 months and severe gum bleeding and generalised petechiae for 1 week. Immune thrombocytopenic purpura (ITP) was indicated by bone marrow findings of megakaryocytic hyperplasia, and her thrombocytopenia responded well to steroid therapy without recurrence, but progressive, deforming polyarthritis with anaemia and thrombocytosis persisted. Case 2 is a 7-year-old girl who presented with spiking fever, arthritis and skin rashes and was suspected of having S-JCA. She developed a severe nosebleed with impending shock while receiving full-dose aspirin. Pancytopenia and elevated liver enzymes were also noted. Bone marrow aspiration revealed erythroid hyperplasia, maturation arrest of myeloid series with increased blasts, and adequate megakaryocytes. Her thrombocytopenia resolved in 1 week without specific treatment. Her subsequent clinical course confirmed the diagnosis of S-JCA, while thrombocytopenia did not recur during follow-up.