Which of the following is considered a primary vasculitis?

• A. Giant-cell arteritis
• B. Hepatitis B–associated necrotizing vasculitis
• C. Drug-induced vasculitis
• D. Virus-associated vasculitis

Answer: (A)

Primary vasculitides are inflammatory diseases of blood vessels with no identifiable external trigger. Giant-cell arteritis is a classic example: it’s an idiopathic granulomatous inflammation of large arteries, typically in adults over 50, without a preceding infection or drug exposure driving the process. This lack of an external trigger is what makes it a primary (idiopathic) vasculitis.

In contrast, hepatitis B–associated necrotizing vasculitis arises as a secondary process, driven by immune complexes formed from hepatitis B antigens that deposit in vessel walls and provoke inflammation. Drug-induced vasculitis is another secondary form, resulting from a hypersensitivity reaction to a medication. Virus-associated vasculitis is also generally considered secondary, linked to an underlying viral infection that triggers vascular inflammation or immune-complex–mediated injury.

So, the condition involving temporal arteries in older adults is the primary vasculitis, whereas the others are secondary to an infectious or drug-related trigger.