A patient presents with respiratory symptoms i.e. cough, hemoptysis and glomerulonephritis. His C-ANCA levels in serum were found to be raised. The most likely diagnosis is –
**Core Concept**
Granulomatosis with polyangiitis (GPA), previously known as Wegener's granulomatosis, is a systemic vasculitis that affects small and medium-sized vessels. It is characterized by the presence of c-ANCA (cytoplasmic anti-neutrophil cytoplasmic antibodies) and granulomatous inflammation in multiple organs, including the lungs and kidneys.
**Why the Correct Answer is Right**
The presence of c-ANCA is a hallmark of GPA, which is a type of ANCA-associated vasculitis. The antibodies target the proteinase 3 (PR3) enzyme in neutrophils, leading to activation of the neutrophils and subsequent inflammation in affected organs. In GPA, the granulomatous inflammation in the lungs (manifesting as cough and hemoptysis) and kidneys (manifesting as glomerulonephritis) is a result of this immune-mediated process.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not specify a systemic vasculitis with granulomatous inflammation and c-ANCA positivity. Other conditions like sarcoidosis may present with similar symptoms but lack c-ANCA positivity.
**Option B:** This option is incorrect because it is a type of vasculitis that primarily affects medium-sized vessels and is associated with p-ANCA (perinuclear anti-neutrophil cytoplasmic antibodies) positivity.
**Option C:** This option is incorrect because it is a type of vasculitis that primarily affects small vessels and is associated with anti-GBM (anti-glomerular basement membrane) antibodies.
**Option D:** This option is incorrect because it is not a specific diagnosis, and the symptoms described are not typical for this condition.
**Clinical Pearl / High-Yield Fact**
GPA is a classic example of a systemic vasculitis that requires prompt recognition and treatment to prevent organ damage and improve patient outcomes. The presence of c-ANCA is a key diagnostic clue, and treatment typically involves a combination of immunosuppressive medications.
**Correct Answer:** C.