This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
Platelet count is decreased in all of the following condition except: 
Select and explain. 
A. H. S. Purpura, B. Idiopathic thrombocytopenic purpura, C. Thrombotic thrombocytopenic purpura, D. Systemic lupus erythematosus
A: H. S. Purpura
Answer: A: H. S. Purpura 
Explanation: Answer is A (H. S. Purpura) The mechanism of ecchymosis or purpura in Henoch Schonlein is vasculitis. There is no thrombocytopenia. All other options are known causes of thrombocytopenia.