This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology and breast, Subject name: Surgery
Serous or serosanguinous nipple discharge may be suggestive of all of the following except 
Select and explain. 
A. Mastitis, B. Carcinoma, C. Duct ectasia, D. Intraductal papilloma
A: Mastitis
Answer: A: Mastitis 
Explanation: Mastitis usually associated with purulent nipple discharge