[Conditions mimicking polymyalgia rheumatica]

To examine the main clinical and laboratory data of patients initially diagnosed with polymyalgia rheumatica (PMR), which then developed another conditions.

We reviewed the clinical records of patients diagnosed with PMR in three hospitals in Argentina. Patients had a diagnosis of PMR if they met the following criteria: age ≥ 50 years, erythrocyte sedimentation rate (ESR) at the time of diagnosis > 40 mm, persistent pain and stiffness of at least one month of evolution in two of the following areas: neck, shoulders or proximal arms, hips or proximal lower limbs. Special attention was paid to symptoms or signs of "alarm" (beginning or during disease progression) for suspecting the presence of other non PMR disease within a period of ≤ 12 months.

Sixteen of the 200 patients (8%) had other diseases during follow up. Malignancies (n=4) and rheumatic diseases (n=4) were the most common entities, in addition to infective endocarditis (n=1), narrow cervical canal (n=1), Parkinson's disease (n=1), statin-related myalgia (n=1), hypothyroidism (n=1), vitamin D deficiency (n=1) and Calcium Pyrophosphate Deposition Disease (CPDD) (n=2). The average length change of diagnosis was 4.5±3 months. Ten patients had no response to steroids and two had persistently elevated ESR.

In this study we highlight the importance of recognizing signs and symptoms along with laboratory data and lack of response to treatment as suspects for the diagnosis of other disease manifestations in patients with PMR symptoms.