Abstract
Anti-signal recognition particle (SRP) myopathy that is recognized as different from PM/DM is a severe, necrotizing, immune-mediated disease characterized by rapidly progressive proximal muscle weakness and markedly elevated serum creatine kinase (CK) levels. Anti-SRP myopathy does not usually associate with skin rash and has poor responsiveness to steroid therapy. Herein, we describe a case of anti-SRP myopathy overlapping with localized morphea, which was diagnosed by histopathologic features and laboratory studies. A 44-year-old man presented with a two year history of erythema on his left upper arm and both cheeks. Although his CK level was high in the laboratory data, an initial biopsy of skin and muscle showed no histological changes consistent with DM. Six Months later, new symptoms, including muscle weakness and pain, appeared; however, no Gottronʼs papules or heliotrope rash was yet observed. At that time, a skin biopsy of cheek showed features consistent with a diagnosis of morphea, and histological examination of muscle revealed necrotizing myopathy without inflammatory cell infiltration. Notably, the anti-SRP antibody was positive in the serum. Based on these findings, we diagnosed this case as localized morphea overlapping with antiSRP myopathy. The systemic corticosteroid therapy was insufficient for controlling his symptoms; therefore cyclosporine A was added to improve his muscle weakness.
