American Board of Internal Medicine (ABIM) Certification Practice Exam

What condition is defined as dermatomyositis with cutaneous involvement without evidence of myositis?

1. Myositis

2. Inclusion body myositis

3. Amyopathic dermatomyositis

4. Polymyositis

The correct answer is: Amyopathic dermatomyositis

The condition defined as dermatomyositis with cutaneous involvement but without evidence of myositis is known as amyopathic dermatomyositis. This condition presents with the characteristic skin manifestations associated with dermatomyositis, such as a heliotrope rash or Gottron's papules, but patients do not exhibit the muscle weakness or inflammation typically seen in myositis. In amyopathic dermatomyositis, the absence of myositis can be particularly challenging since patients might initially present with skin findings leading to misdiagnosis or oversight of muscle involvement. However, distinguishing this condition is crucial for appropriate management and understanding the clinical spectrum of dermatomyositis. In contrast, conditions such as myositis, inclusion body myositis, and polymyositis involve muscular inflammation and weakness, which are not present in amyopathic dermatomyositis. The specificity of amyopathic dermatomyositis lies in its isolation of cutaneous features without concurrent muscle pathology, making it a distinct entity within the myositis family.