A subset of systemic lupus erythematosus with progressive cystic bone lesions.

Clinical and serological findings of 16 patients with systemic lupus erythematosus (SLE) who had progressive cystic bone lesions were compared with a control group of 19 patients with SLE without radiological evidence of bone cysts. Central nervous system manifestations, synovitis, and other radiologically observed skeletal abnormalities were more prevalent in the patients with cysts than in the control group. Higher concentrations of C reactive protein, and a greater incidence of rheumatoid factor positivity were seen in the patients with cysts than in the control patients, but no other serological differences were found. It is suggested that patients with SLE with progressive cystic lesions form a subgroup of the syndrome characterised by an increased acute phase reaction.