An elderly female presents to the emergency depament with history of fever, headache and double vision. Biopsy of temporal aery revealed panaeritis. The most likely diagnosis is
**Core Concept**
Granulomatosis with polyangiitis (GPA), formerly known as Wegener's granulomatosis, is a form of vasculitis that primarily affects small- and medium-sized vessels, often presenting with systemic symptoms and granulomatous inflammation. The condition is characterized by the presence of anti-neutrophil cytoplasmic antibodies (ANCA), particularly c-ANCA (PR3-ANCA), which targets proteinase 3.
**Why the Correct Answer is Right**
The patient's symptoms, including fever, headache, and double vision, suggest a systemic inflammatory process. The biopsy of the temporal artery revealing panarteritis is a hallmark of GPA, indicating inflammation of the blood vessel walls. The presence of granulomatous inflammation and vasculitis in the biopsy sample points towards GPA. The involvement of the temporal artery is a classic feature of GPA, which can lead to symptoms such as double vision due to orbital involvement.
**Why Each Wrong Option is Incorrect**
* **Option A:** Giant cell arteritis (GCA) is a form of vasculitis that primarily affects large vessels, particularly the temporal arteries, but it typically presents with pain and tenderness over the affected area, not double vision.
* **Option B:** Polyarteritis nodosa (PAN) is a form of vasculitis that affects medium-sized vessels and can present with systemic symptoms, but it is less likely to involve the temporal arteries and does not typically present with granulomatous inflammation.
* **Option C:** Microscopic polyangiitis (MPA) is a form of vasculitis that primarily affects small vessels and can present with systemic symptoms, but it is less likely to involve the temporal arteries and does not typically present with granulomatous inflammation.
**Clinical Pearl / High-Yield Fact**
GPA is a classic example of a condition where the presence of ANCA, particularly c-ANCA (PR3-ANCA), can aid in diagnosis. Remember that GPA often presents with a triad of symptoms: upper respiratory tract symptoms, renal involvement, and systemic symptoms.
**Correct Answer:** C