Late onset undifferentiated spondyloarthritis presenting with polymyalgia rheumatica features: description of seven cases

To underline the importance of considering a diagnosis of undifferentiated spondyloarthritis (uSpA) in patients presenting polymyalgia rheumatica (PMR) features. All patients with late onset uSpA meeting criteria for PMR at the onset of their disease seen in the Rheumatology Division of Xeral-Calde Hospital of Lugo, Spain during a 5 year period, and in the Rheumatology Department of Lucania, Italy in a two and a half year period, were studied. Six patients with late onset uSpA showing PMR symptoms at the onset were seen during the study periods in the two centres. Another patient had previously been observed in Lugo in a study dealing with the spectrum of conditions mimicking PMR. Of the seven patients, five had manifestations of SpA at the beginning of the disease and two developed these in the following 6 months. All seven met the Amor and/or the ESSG criteria for classifying and diagnosing SpA. The possibility that late onset uSpA may have PMR-like features at the beginning of the disease should be taken into account. The diagnosis is not difficult if the entire clinical spectrum of SpA is considered.