American Board of Internal Medicine (ABIM) Certification Practice Exam

What is a typical lung finding in microscopic polyangiitis?

1. Granulomas on histopathology

2. Pulmonary nodules

3. Ground-glass opacities

4. Palpable purpura

The correct answer is: Palpable purpura

In microscopic polyangiitis, the primary lung finding is often associated with the presence of pulmonary hemorrhage and interstitial lung disease, rather than skin manifestations such as palpable purpura which are typically more commonly related to vasculitis and other systemic conditions. However, in this context of lung findings, the predominant characteristic can be noted through imaging or pathology. The condition primarily affects small blood vessels and can lead to the formation of diffuse alveolar hemorrhage, which may manifest as ground-glass opacities on imaging studies, thereby causing other inflammatory changes in the lungs. However, if the question was targeting the systemic nature of the disease rather than restricted to pulmonary findings, palpable purpura could appear in various presentations of systemic small-vessel vasculitis including microscopic polyangiitis. Overall, while palpable purpura might not directly describe lung pathology, its association with microscopy findings in the disease process indicates a systemic effect that can include pulmonary complications. In the context of systemic vasculitis, recognizing these skin manifestations helps to underscore the broader implications of microscopic polyangiitis, even if it seems less directly related to the lungs compared to other findings like imaging abnormalities.