Question

In which of the following conditions is granulomatous vasculitis NOT seen?

• A. Microscopic Polyangiitis
• B. Wegener's Granulomatosis
• C. Giant Cell Arteritis
• D. Churg-Strauss Syndrome

Hint:

Of the ANCA-associated vasculitides, this one is pauci-immune without granuloma formation.

Answer 1

The Correct Option is A

Step 1: Recall what granulomatous vasculitis means.
Granulomatous vasculitis is inflammation of blood vessel walls with granuloma formation, clusters of macrophages, giant cells, and lymphocytes trying to wall off an injury.

Step 2: List the vasculitides that are granulomatous.
Giant cell (temporal) arteritis shows granulomas with multinucleated giant cells in the media of large arteries. Wegener's granulomatosis, now called granulomatosis with polyangiitis, has necrotising granulomas in the respiratory tract along with small vessel vasculitis. Churg-Strauss syndrome, now called eosinophilic granulomatosis with polyangiitis, also forms granulomas, along with heavy eosinophil infiltration and asthma.

Step 3: Check microscopic polyangiitis.
Microscopic polyangiitis is a pauci-immune, ANCA-associated small vessel vasculitis. It causes necrotising inflammation of capillaries, venules, and arterioles, but it does not form granulomas. This is the key feature that separates it from Wegener's and Churg-Strauss, both of which are also ANCA-associated but do form granulomas.

Step 4: Rule out the other options.
Since giant cell arteritis, Wegener's granulomatosis, and Churg-Strauss syndrome all show granuloma formation, the only condition left without granulomas is microscopic polyangiitis.

Step 5: Final answer.
Granulomatous vasculitis is not seen in microscopic polyangiitis.
\[ \boxed{\text{Microscopic Polyangiitis}} \]