Rheumatic fever and disorders of the musculoskeletal system.

New information provided on the pathogenesis and management of rheumatic fever is of current interest. Invasive disease by group A streptococci has been shown to be due to production of toxin A. The natural history and immunopathologic basis for chronic Lyme arthritis are reported. Attention is drawn to pyomyositis and clinical presentation of chronic fatigue syndrome in children. Patients with Sweet's syndrome often have antineutrophil cytoplasmic autoantibodies. Biopsy specimens of panniculitis should be taken to aid treatment. Long-term outcome in chronic osteomyelitis is favorable; recommendations on the rational use of imaging have been reported.