The pale and limping child.

A 13 year old girl presented with a two month history of recurrent episodes of arthritis of the metacarpophalangeal, wrist, knee, ankle, and metatarsophalangeal joints. The arthritis seemed to follow a migratory and symmetric pattern. The arthritis lasted for a week, resolved spontaneously, only to recur a few days later in another joint. Apart from having intermittent low grade fever, she was well. There was no history of sore throat, diarrhoea, or rash. On examination she was pyrexial (temperature 37.6°C). There was pallor, hepatomegaly (liver span measuring 17 cm), and moderate splenomegaly. The left and right first metacarpophalangeal joints were swollen and tender while there were residual swellings of the ankles. Initial investigations revealed a haemoglobin of 89 g/l, leucocyte count of 7.3 × 10/l with normal diVerential count and platelet count of 82 × 10/l. Erythrocyte sedimentation rate was 125 mm/hour. Levels of complement and immunoglobulins were normal. Rheumatoid factor, HLA B27, antinuclear, anti-double stranded DNA, and antistreptolysin O antibodies were negative. Culture results were unremarkable. The patient received non-steroidal anti-inflammatory drugs and two units of red cells. Two weeks later she returned with worsening of the arthritis and generalised lymphadenopathy. The platelet count dropped to 16 × 10/l. Peripheral blood and bone marrow smears are shown in fig 1A and B respectively.