[A case of polymyalgia rheumatica with excessive increase of rheumatoid factor]

A 76 year-old woman suffered from muscle pain and stiffness of acute onset in her shoulder girdle and pelvic girdle, which were followed by mild left temporal headache and transient arthralgia. Neither joint swelling nor sicca symptom was observed. Laboratory data showed high ESR (128 mm/hr), positive CRP (12.9 mg/dl), increased fibrinogen (485 mg/dl) and high titer of rheumatoid factor (RF) (RAHA x 640). Other autoantibodies examined were negative. Muscle enzymes and electromyogram were within normal limits. Joint X ray didn't reveal the finding suggestive of RA. After the treatment with prednisolone (PSL) 15 mg/day, clinical symptoms and laboratory data improved dramatically. Though she had excessive increase of RF (RAHA x 10240) during therapy, no recurrence of articular symptoms were recognized. She continues to be well with PSL 5 mg/day after 1 year 5 months from onset. As for polymyalgia rheumatica (PMR) followed by RA, the appearance or exacerbation of arthritis corresponding to the elevation of RF occurred in all previously reported 17 cases. Recurrence of arthralgia corresponding to the elevation of RF was not recognized in this case. In addition, Hunder et al reported that PMR with little or no observable joint swelling after several weeks of symptoms is unlikely to develope RA. Therefore, it is speculated that this case in unlikely to develope RA and assessment of arthritis corresponding to the elevation of RF is important to differentiate PMR and elderly-onset RA. This case of PMR is the 5th case with excessive increase of RF in Japan.