American Board of Internal Medicine (ABIM) Certification Practice Exam

What is a primary characteristic of Polyarteritis nodosa (PAN)?

1. It primarily affects small blood vessels.

2. It leads to systemic vasculitis affecting large arteries.

3. It causes nephron hypertrophy.

4. It is associated with direct renal infection.

The correct answer is: It leads to systemic vasculitis affecting large arteries.

Polyarteritis nodosa (PAN) is characterized by its effect on medium-sized muscular arteries, leading to systemic vasculitis primarily affecting these vessels rather than small blood vessels. This means that PAN can impact various organ systems, resulting in a wide range of symptoms due to the ischemia caused by the inflammation of the arteries. The involvement of medium-sized arteries distinguishes PAN from other forms of vasculitis that primarily affect small vessels, such as granulomatosis with polyangiitis or microscopic polyangiitis, thus highlighting the specific nature of PAN's vascular involvement. The systemic nature of PAN can lead to complications including organ damage and can potentially affect large arteries as part of the broader route of systemic vasculitis. While PAN can cause renal complications, it does not lead directly to nephron hypertrophy nor is it associated with direct renal infections, which are not defining characteristics of this condition. The focus on the inflammation of medium and large arteries helps clarify the understanding of PAN's pathophysiology.