Anti-Signal Recognition Particle (SRP) associated myopathy is a clinically and histopathologically distinct subgroup of Juvenile Idiopathic Inflammatory Myositis (JIIM), which is under-recognised in children and fails to respond to conventional first line therapies. Thus far, the paediatric literature has demonstrated a picture consistent with the adult population, however only a handful of cases have been reported. Currently the limited number of cases precludes definitive conclusions to guide clinicians in their management and thus a variety of therapies have been trialled on an individual basis, with variable success. In this paper, the authors present three new cases of anti-SRP myositis and relate this to the published literature. This report highlights the use of an aggressive induction regime where standard therapy failed, including combination of intravenous immunoglobulin (IVIG), cyclophosphamide and rituximab, with intensive physical therapy, which resulted in positive outcomes in each case. This paper supports the hypothesis that anti-SRP myositis is distinct from other JIIM. It is an important differential to JDM and should be considered where there is severe weakness without rash or if highly elevated muscle enzymes (CK > 10,000 U/l) are found. Early identification is essential to initiate aggressive medical and physical therapy. Greater international collaboration and long-term follow-up data is needed to establish the most effective treatment strategy for this rare group of patients.
