Rituximab therapy in necrotizing autoimmune myopathy associated with anti-SRP antibody: A clinical case review.

Necrotizing autoimmune myopathy (NAM) is a rare and emerging entity of idiopathic inflammatory myopathy (IIM). They have been associated with connective tissue disorders, viral infections, malignancy, anti-signal recognition particle (SRP) and anti-3-hydroxy-3-methylglutaryl-coenzyme A reductase protein (with or without the use of statins). Anti-SRP associated NAM has different clinical and histological characteristics that differentiate them from other IIM, resulting in a poor prognosis. Very few cases treated with rituximab have been published, with varying clinical response. Here we describe a case of anti-SRP associated NAM refractory to conventional immunosuppressants and its successful long-term management with the combination of rituximab, corticosteroids and methotrexate.