Inflammatory myopathy with anti-SRP antibodies: case series of a South Australian cohort

• Published in: Clinical rheumatology Vol. 34; no. 3; pp. 603 - 608
• Main Authors: Basnayake, Sajini K, Blumbergs, Peter, Tan, Ju Ann, Roberts-Thompson, Peter J, Limaye, Vidya
• Format: Journal Article
• Language: English
• Published: London Springer London 01-03-2015; Springer Nature B.V
• Subjects: Aged, 80 and over; Case Based Review; Humans; Male; Medicine; Medicine & Public Health; Middle Aged; Muscles - pathology; Myositis - immunology; Myositis - pathology; Rheumatology; Signal Recognition Particle - immunology; Necrotizing myopathy; Myositis; Polymyositis; Histopathology; SRP antibodies; Muscle biopsy
• DOI: 10.1007/s10067-014-2512-7
• EISSN: 1434-9949
• ISSN: 0770-3198

Myopathy associated with anti-signal recognition particle (SRP) antibodies is a rare form of myopathy, which is thought to be distinct from classic polymyositis. We sought to determine the demographic, clinical and histopathological features of patients with anti-SRP antibodies. Hence we undertook an audit of patients with histologically-confirmed myositis who had anti-SRP antibodies. Of 144 patients with inflammatory myositis tested for myositis-specific and myositis-associated antibodies between 2007 and 2011 inclusive, five with anti-SRP antibodies were identified. All five were male, four had severe proximal weakness, one was asymptomatic and three had dysphagia. None had cardiovascular involvement. All patients showed isolated anti-SRP positivity and absence of antinuclear antibodies. Muscle histopathology showed variable myofibre necrosis, and most had an inflammatory infiltrate. Majority showed a favorable response to combination immunosuppressive therapy. Myopathy associated with anti-SRP antibodies is clinically heterogeneous in presentation. Muscle histopathology shows a mixture of necrotic and inflammatory features.