American Board of Internal Medicine (ABIM) Certification Practice Exam

Polymyositis and dermatomyositis are idiopathic inflammatory myopathies characterized by muscle weakness and, in the case of dermatomyositis, distinctive skin rashes. The presence of specific autoantibodies helps in diagnosing and understanding the underlying pathophysiology of these conditions.

The correct answer is centered around the autoantibodies known to be associated with polymyositis and dermatomyositis. Anti-Jo-1, Anti-SRP, and Anti-Mi-2 are particularly significant.

- Anti-Jo-1 antibodies are directed against histidyl-tRNA synthetase and are often present in patients with polymyositis or dermatomyositis, often associated with interstitial lung disease. Their prevalence underscores the autoimmune nature of these conditions.

- Anti-SRP (signal recognition particle) antibodies are also associated with polymyositis. The presence of these antibodies indicates a more severe form of the disease and has implications for long-term outcomes and treatment approaches.

- Anti-Mi-2 antibodies, specific for dermatomyositis, are associated with the characteristic skin manifestations as well as muscle weakness, emphasizing the link between autoimmunity and the dermatological features of the disease.

In contrast, the other options include