Which of the following vasculitis is ANCA negative
**Core Concept**
Vasculitis refers to inflammation of blood vessels, which can be classified into different types based on the size and location of the affected vessels. ANCA (Anti-Neutrophil Cytoplasmic Antibodies) negativity or positivity is a crucial diagnostic criterion for certain types of vasculitis.
**Why the Correct Answer is Right**
Polyarteritis nodosa (PAN) is a medium-sized vessel vasculitis characterized by necrotizing inflammation of the arterial walls, leading to aneurysm formation and organ damage. Unlike other forms of vasculitis, PAN is not associated with ANCA positivity. Instead, it is often linked to hepatitis B infection or other autoimmune disorders. The absence of ANCA in PAN is due to the distinct pathophysiology and immune mechanisms involved in this condition.
**Why Each Wrong Option is Incorrect**
**Option A:** Microscopic polyangiitis (MPA) is a small-sized vessel vasculitis associated with ANCA positivity, particularly p-ANCA (perinuclear ANCA) or c-ANCA (cytoplasmic ANCA). MPA is characterized by the presence of ANCA, which targets proteinase 3 or myeloperoxidase.
**Option B:** Churg-Strauss syndrome (CSS), also known as eosinophilic granulomatosis with polyangiitis (EGPA), is a small-sized vessel vasculitis linked to ANCA positivity, particularly p-ANCA. CSS is characterized by the presence of ANCA and eosinophilia, which distinguishes it from other forms of vasculitis.
**Option C:** Granulomatosis with polyangiitis (GPA), formerly known as Wegener's granulomatosis, is a small-sized vessel vasculitis associated with ANCA positivity, particularly c-ANCA. GPA is characterized by the presence of ANCA targeting proteinase 3 and granulomatous inflammation.
**Clinical Pearl / High-Yield Fact**
It is essential to remember that ANCA negativity does not rule out vasculitis, as certain forms like Polyarteritis nodosa do not exhibit ANCA positivity. However, ANCA negativity can help narrow down the differential diagnosis and guide further investigations.
**✓ Correct Answer:** D. Polyarteritis nodosa