DefinitionIntraductal papilloma is a small, noncancerous (benign) tumor that grows in a milk duct of the breast.Causes, incidence, and risk factorsIntraductal papilloma occurs most often in women ages 35 - 55. The causes and risk factors are unknown.SymptomsBreast enlargementBreast lumpBreast painNipple dischargeSigns and testsIntraductal papilloma is the most common cause of spontaneous nipple discharge from a single duct.The health care professional might feel a small lump beneath the nipple, but this lump cannot always be felt (palpable). A mammogram often does not show papillomas. Ultrasound may be helpful.Other tests include:A breast biopsyto rule out cancerAn examination of the discharge to see if the cells are cancerous (malignant)An x-ray with contrast dye injected into the affecte