Three cases of immune‐mediated necrotizing myopathy with anti‐signal recognition particle antibodies: Extramuscular symptoms preceding progressive muscle weakness

Abstract

Immune‐mediated necrotizing myopathy with an anti‐signal recognition particle antibody (anti‐SRP myopathy) is generally refractory to treatment. Anti‐SRP myopathy is characterized by muscle weakness as the main symptom, but is often complicated by extramuscular symptoms. Rarely, the extramuscular symptoms precede muscle weakness. In the present report, we describe the clinical presentation and medical history of three patients with extramuscular symptoms. Focusing on the extramuscular symptoms, anti‐SRP antibody‐positive myopathy can be diagnosed at an early stage. It might therefore be treatable before muscle weakness progresses.