This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immunology and Rheumatology, Subject name: Medicine
A 24-year-old woman presents with abdominal pain, joint discomfort, and lower limb rash. She was well until 1 week before presentation. On examination, she has a palpable purpuric rash on her legs, nonspecific abdominal discomfort, and no active joints. She has 3+ proteinuria, normal WBC, no eosinophils, and elevated creatinine of 1.6 mg/dL. Biopsy of the rash confirms vasculitis with immunoglobulin A (IgA) 3+and C3 (complement 3) deposition on immunofluorescence.For the above patient with vasculitis syndrome, select the most likely diagnosis. 
Select and explain. 
A. polyarteritis nodosa (PAN), B. Churg-Strauss disease, C. Henoch-Schonlein purpura, D. vasculitis associated with infectious diseases
C: Henoch-Schonlein purpura
Answer: C: Henoch-Schonlein purpura 
Explanation: Henoch-Schonlein purpura, characterized by palpable purpura, arthralgias, GI symptoms, and glomerulonephritis, can be seen in any age-group but is most common in children. It can resolve and recur several times over a period of weeks or months and can resolve spontaneously.