Necrotizing autoimmune myopathies (NAM) are typically a subacute course with symmetric and proximal weakness described in the upper and lower extremities.   CKs are often elevated in the thousands and two antibodies are isolated in seropositive cases: Anti-HMGCR and anti-SRP.  Systemic Lupus Erythematous (SLE) has been previously associated with overlap syndrome but has only been described in a single case report of necrotizing myopathy though antibody status was not confirmed.   We present the case of a 21-year-old woman with nascent SLE with severe and acute nephritis and myocarditis who developed a proximal necrotizing myopathy.

21-year-old woman with no past medical history was admitted to the hospital with acute gastritis.  Over a several week period, she developed nephritis requiring frequent dialysis, myocarditis and cerebritis necessitating aggressive immunotherapy including rituximab, hydroxychloroquine, cyclophosphamide and methylprednisolone.  Serology revealed elevated anti-double stranded DNA antibodies and other autoimmune markers meeting criteria for SLE.  On her 26^th day of admission, she developed weakness in all extremities and mild pain/tenderness in her shoulders/calves.  Exam was notable for symmetric, proximal upper and lower extremity weakness with preserved sensation and reduced reflexes globally.  CKs were first noted as normal on admission but were seen as high as 3042 after weakness began.  MRI of the femur revealed inflammatory changes.  Quadriceps muscle biopsy demonstrated florid myophagocytosis with absence of inflammatory cells and connective tissue invasion.  There were no biopsy findings to support a hydroxychloroquine myopathy.  Antibody testing demonstrated a negative myositis panel and anti-SRP antibodies.  Her anti-HMGCR is pending.  Her weakness improved and CKs normalized within seven days of treatment with IVIG and steroids. 

This case represents a rare, biopsy proven NAM induced by SLE without meeting criteria for overlap myositis. These findings suggest that SLE be considered as a possible etiology for NAM cases.