This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: NEET Jan 2020, Subject name: Pathology
Which of the following is true about polyaeritis nodosa? 
Select and explain. 
A. It shows fibrinoid necrosis in large blood vessels, B. It has ANCA positivity, C. HBsAg is positive in 30% patients, D. Affected individuals have involvement of pulmonary circulation.
C: HBsAg is positive in 30% patients
Answer: C: HBsAg is positive in 30% patients 
Explanation: This condition is characterized by necrotizing immune complex inflammation of small- and medium-sized aeries. It is marked by the destruction of aerial media and internal elastic lamella, resulting in aneurysmal nodules. There is an association with hepatitis B viral infection in 30% of patients. Clinical manifestations often include fever, weight loss, malaise, abdominal pain, headache, myalgia, and hypeension. Polyaeritis nodosa is seen in the following sites: Kidneys, with immune complex vasculitis in the aerioles and glomeruli; renal lesions, and hypeension cause most deaths from polyaeritis nodosa. Coronary aeries, resulting in ischemic hea disease Musculoskeletal system, resulting in myalgia, ahralgia, or ahritis Gastrointestinal tract, manifesting as nausea, vomiting, or abdominal pain Central nervous system (CNS) or peripheral nervous system, the eye, or skin