P.14.10 Respiratory failure as presenting symptom of paraneoplastic necrotizing autoimmune myopathy

Abstract

Necrotizing autoimmune myopathy (NAM) is associated with cancer, connective tissue disorders, and statin use. Respiratory failure as a presenting symptom has been reported in rare cases of other inflammatory myopathies, but not in NAM. A 48-year-old woman was acutely admitted with severe hypercapnia which required immediate endotracheal intubation. History revealed that she experienced shortness of breath since one month. Her past medical history included a mastectomy 2years prior to admission, because of noninvasive ductal mammacarcinoma. On admission there was mild symmetrical proximal weakness of her arms and legs and slightly more pronounced distal weakness of her legs, as well as weakness of her neck flexor muscles, which in retrospect had been gradually progressive in the weeks before presentation. Serum creatine kinase activity was five times the upper limit of normal and electromyography exhibited extensive myopathic changes. Magnetic resonance imaging (T2 weighted images) showed hyperintensity of the pelvic girdle and proximal leg muscles. Muscle biopsy showed extensive muscle fibre necrosis in the absence of inflammatory cells. Myositis immunoblot did not show myositis specific antibodies. A diagnosis of paraneoplastic NAM was made and monthly courses of oral dexamethasone pulse therapy was started which led to prompt extubation and remarkable recovery of muscle strength in weeks. Acute respiratory failure can be a presenting symptom in paraneoplastic necrotizing autoimmune myopathy. Paraneoplastic NAM should be considered in all patients with (sub) acute onset of symmetrical and progressive limb weakness and a history of malignancy. Immunosuppressive therapy can lead to substantial recovery.