Late-onset rheumatoid arthritis vs polymyalgia rheumatica: making the diagnosis.

Differentiating polymyalgia rheumatica from the onset of rheumatoid arthritis in the elderly has been the cause of much unnecessary confusion. Differential diagnosis of these disorders can be straightforward. A strategy is outlined, comprising a complete history, attention to clinical signs, and appropriate use of laboratory diagnostics. The clinical picture of each disorder is discussed, as are common obstacles to diagnosis.