Hi practo user , You have not mentioned about the type of discharge from your nipple which can be : 1) blood 2) serous 3) pus 4) Milky And USG suggestive of cyst of size 4 mm in left breast with birad 2 suggestive of a benign lesion but if you have noticed any increase in size of your cyst or any lump in your breast consult your doctor Do a regular self breast examination and in any doubt kindly consult a surgeon to get it examined so that it can be managed properly and timely . For further assistance kindly connect .. Hope this helps