Which vasculitis affects both aerial and venous system
**Core Concept**
Polyarteritis nodosa (PAN) is a type of systemic vasculitis that affects medium-sized arteries, but it can also involve smaller arteries and veins. This condition is characterized by necrotizing inflammation of the blood vessel walls, leading to vascular damage and organ dysfunction.
**Why the Correct Answer is Right**
The correct answer is associated with PAN, which is known to affect both arterial and venous systems. PAN is a form of necrotizing vasculitis that affects the medium-sized arteries, but it can also involve smaller arteries and veins, leading to a wide range of systemic symptoms. The exact pathogenesis of PAN is not fully understood, but it is thought to involve an immune-mediated response to an unknown antigen, leading to the activation of various cellular and molecular pathways that result in vascular inflammation and damage.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because Microscopic polyangiitis (MPA) primarily affects small-sized arteries and capillaries, but it is not typically associated with involvement of the venous system.
**Option B:** This option is incorrect because Giant cell arteritis (GCA) primarily affects large and medium-sized arteries, but it is not typically associated with involvement of the venous system.
**Option C:** This option is incorrect because Eosinophilic granulomatosis with polyangiitis (EGPA) primarily affects small-sized arteries and capillaries, but it is not typically associated with involvement of the venous system.
**Option D:** This option is incorrect because Wegener's granulomatosis (now known as Granulomatosis with polyangiitis) primarily affects small-sized arteries and capillaries, but it is not typically associated with involvement of the venous system.
**Clinical Pearl / High-Yield Fact**
PAN is a classic example of a systemic vasculitis that can affect multiple organ systems, and it often presents with a wide range of nonspecific symptoms such as weight loss, fever, and fatigue. A high index of suspicion is necessary for diagnosis, and biopsy of an affected organ or vessel is often required to confirm the diagnosis.
**Correct Answer: C. PAN**