Pauci immune glomerulonephritis is seen in the following condition:
**Core Concept**
Pauci-immune glomerulonephritis is a type of glomerulonephritis characterized by minimal or absent immune complex deposition on immunofluorescence microscopy. This condition is often associated with the presence of antineutrophil cytoplasmic antibodies (ANCA) and is typically seen in small vessel vasculitides such as granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA).
**Why the Correct Answer is Right**
The pathogenesis of pauci-immune glomerulonephritis involves the activation of neutrophils and the release of proteases, leading to endothelial injury and glomerular damage. The absence of immune complex deposition is thought to be due to the rapid clearance of immune complexes by neutrophils, rather than a lack of immune complex formation. The presence of ANCA is believed to contribute to the activation of neutrophils and the perpetuation of the inflammatory response.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not specify a condition associated with pauci-immune glomerulonephritis. While some forms of lupus nephritis may exhibit minimal immune complex deposition, it is not a hallmark of this condition.
**Option B:** This option is incorrect because it is a type of immune complex glomerulonephritis, characterized by the presence of immune complexes on immunofluorescence microscopy.
**Option C:** This option is incorrect because it is not typically associated with pauci-immune glomerulonephritis. While some forms of vasculitis may exhibit immune complex deposition, it is not a characteristic of this condition.
**Clinical Pearl / High-Yield Fact**
It is essential to distinguish between pauci-immune and immune complex glomerulonephritis, as the former is often associated with ANCA-positive vasculitides and requires a different treatment approach.
**Correct Answer: C. Granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA).**