The ying and yang of fever in rheumatic disease.

Fevers are relatively common in rheumatic disease, largely due to the fact that the inflammatory process is driven by inflammatory mediators that function as endogenous pyrogens. Since the immune system's sensors cannot accurately distinguish between endogenous and exogenous (pathogen-derived) pyrogens a major challenge for physicians and rheumatologists has been to decipher patterns of clinical signs and symptoms to inform clinical decision making. Here we describe some of the common pitfalls and clinical challenges, and highlight the importance of a systematic approach to investigating the rheumatic disease patient presenting with fever.