Hip abductor weakness in anti-signal recognition particle antibody-positive myopathy

A 40-year-old man presented with a 3-month history of progressive weakness of the four limbs. On examination, weakness of the hip abductor was marked. While walking, shoulder sway was noted as a compensation for hip abductor weakness. Blood tests showed a marked elevation of creatine kinase (CK) level and the presence of anti-signal recognition particle (SRP) antibodies. Thigh muscle MRI demonstrated the presence of inflammation in various muscles including the gluteus medius. Clinicians should consider the possibility of anti-SRP antibody-positive myopathy in patients presenting with hip abductor weakness in a subacute onset.