P16. Overlap Myositis in Felty Syndrome with mitochondrial affection

Abstract

Overlap Myositis is a rare complication of auto-inflammatory disorders that presents as an add-on muscle weakness with increased creatin kinase. A 34 year old woman presented with myalgia in both thighs that increased with exercise and spread out to the lower extremities. She reported accompanying weakness of the proximal muscles of the upper and lower limbs that was objectified by clinical examination as paresis grade 4/5 in the MRC score. There was a history of rheumatic ailment for ten years with diagnosis of Felty Syndrome 2.5 years ago. Level of the creatine kinase presented normal with 2.47 μ kat/l (147.71 U/l); (normal μ kat/l, Histologically polymyositis with COX-negative fibers was diagnosed. That is most likely a presentation of an overlap myositis in the context of the rheumatological disease. This case demonstrates a rare finding of Felty syndrome that is associated with myositis. The massive inflammation despite immunosuppressive therapy and the extent of mitochondrial dysfunction are extraordinary features that suggest an ongoing disease with the need for a more aggressive immunosuppression.