Diagnostic errors in polymyalgia rheumatica and temporal arteritis.

Incomplete clinical response or persistence of a rapid ESR despite corticosteroid treatment of polymyalgia rheumatica or temporal arteritis should always arouse suspicion and prompt a search for other diagnoses. Lumbar spinal stenosis and Pancoast's tumor are two unusual entities that can complicate or compete for the diagnosis of polymyalgia rheumatica and temporal arteritis.