10 nov. 2022 · Black liquid (black nipple discharge) coming out of the breast may indicate blood is present, which can have several causes, such as a benign (non-cancerous) growth within a milk duct (papilloma), a persistently dilated milk duct (duct ectasia), or a chronic abscess near the nipple. Causes of abnormal nipple discharge that may be black or other colors include duct ectasia, duct papilloma.