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**
The patient's presentation of respiratory symptoms, such as cough and hemoptysis, in conjunction with glomerulonephritis, suggests an autoimmune disorder affecting the kidneys and lungs. The elevated c-ANCA levels indicate the presence of anti-neutrophil cytoplasmic antibodies, which are a hallmark of certain vasculitides.
**Why the Correct Answer is Right**
The patient's symptoms and laboratory findings are consistent with Granulomatosis with Polyangiitis (GPA), formerly known as Wegener's Granulomatosis. GPA is a form of ANCA-associated vasculitis that affects small- to medium-sized vessels, leading to inflammation and damage in various organs, including the kidneys (glomerulonephritis) and lungs (cough, hemoptysis). The presence of c-ANCA antibodies, specifically PR3-ANCA, is a key diagnostic criterion for GPA.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is not provided, but if it were a distractor, it might imply a different diagnosis, such as Goodpasture syndrome, which also presents with glomerulonephritis and pulmonary symptoms. However, Goodpasture syndrome is typically associated with anti-GBM antibodies, not c-ANCA.
* **Option B:** This option might suggest a diagnosis of Microscopic Polyangiitis (MPA), another form of ANCA-associated vasculitis. While MPA can present with similar symptoms to GPA, it is more commonly associated with p-ANCA (MPO-ANCA) rather than c-ANCA.
* **Option C:** This option might imply a diagnosis of Eosinophilic Granulomatosis with Polyangiitis (EGPA), formerly known as Churg-Strauss syndrome. EGPA is also a form of ANCA-associated vasculitis, but it is more commonly associated with asthma and eosinophilia, rather than the respiratory symptoms described in the question.
**Clinical Pearl / High-Yield Fact**
In patients presenting with respiratory symptoms and glomerulonephritis, a high index of suspicion for ANCA-associated vasculitis, such as GPA, is essential. Prompt recognition and treatment can significantly improve outcomes in these patients.
**Correct Answer:** C.