Question

Consider the following statements regarding classic polyarteritis nodosa:
1. It is multi-system necrotising vasculitis
2. Small and medium vessels are involved
3. Pulmonary artery involvement is a characteristic feature
4. Up to 30% patients may test positive for Hepatitis B surface antigen.

Which of these statements are correct?

• A. 1 and 2
• B. 2 and 3
• C. 1, 2 and 4
• D. 2, 3 and 4

Hint:

Remember which organ classic PAN is taught to spare.

Answer 1

The Correct Option is C

This question tests how well the definition of classic polyarteritis nodosa (PAN) is remembered, by asking which of four statements about it are true.

1. Statement 1, multi-system necrotising vasculitis: true. PAN damages arteries feeding many different organs at once, including kidney, gut, skin, nerve and muscle.
2. Statement 2, small and medium vessels involved: true. Classic PAN is a disease of medium sized muscular arteries, with some small artery involvement, though it spares the tiniest vessels like arterioles and capillaries.
3. Statement 3, pulmonary artery involvement is characteristic: false. One of the defining features taught about classic PAN is that the lungs are typically spared. Lung disease points more toward microscopic polyangiitis or ANCA associated vasculitis, not classic PAN.
4. Statement 4, up to 30% test positive for Hepatitis B surface antigen: true. Chronic Hepatitis B infection is a recognised trigger for PAN through immune complex mediated vessel injury, and this figure is a commonly quoted association.

Three of the four statements, 1, 2 and 4, hold up against the standard description of classic PAN, while statement 3 contradicts the well known fact that the lungs are spared.

Let's summarize:

• Classic PAN affects small and medium arteries across multiple organs, and is linked to Hepatitis B in up to 30% of cases.
• It characteristically spares the lungs, so pulmonary artery involvement is not a feature.

So the statements that are correct are 1, 2 and 4.