The development of necrotizing myopathy after<unk>  exposure is insufficient to make the diagnosis. Testing must first exclude other causes of myositis and necrotizing myopathy. A muscle biopsy consistent with SAAM will demonstrate muscle cell death with muscle fiber regeneration and typically has few inflammatory cells. Immunohistochemistry testing may demonstrate additional pathologic features of SAAM. Such findings include the presence of endothelial cell membrane attack complex in non-necrotic muscle fibers and MHC class I expression. Antibodies against HMG-CoA reductase occur in 94% of affected individuals. These antibodies are known to also occur in people who do not take<unk>  medications. Conversely, these antibodies are absent in people who take<unk>  medications but do not have myopathy. Thus, the presence of anti-HMG CoA reductase antibodies in someone who uses a<unk>  and has myopathy strongly supports the diagnosis. CK levels increase to 10-100 times above normal (2000-20,000 IU/L) in more than 90% of cases. Electromyography (EMG) typically demonstrates a myopathic pattern of findings. Muscle swelling may be seen on MRI imaging.
Statin-associated autoimmune myopathy
Desmin-related myofibrillar myopathy
Acquired non-inflammatory myopathy
Dermatopolymyositis
Inclusion body myositis
Scleromyositis
Dermatomyositis
Hereditary inclusion body myopathy