A 38-year-old woman reports intermittent blood-stained nipple discharge from one breast with no palpable mass. Imaging shows a small subareolar lesion. Biopsy shows papillary fronds with fibrovascular cores lined by a double layer of luminal epithelial cells overlying myoepithelial cells. What is the diagnosis?

• A Intraductal papilloma ✓
• B Papillary carcinoma
• C Duct ectasia
• D Mammary duct fistula

Explanation

Intraductal papilloma is the classic cause of serous or bloody nipple discharge in a premenopausal woman without a mass. The defining benign feature is the double cell layer: cuboidal to columnar epithelium overlying an intact myoepithelial layer on each fibrovascular frond. Loss of the myoepithelial layer would favor papillary carcinoma, making that the key distractor this finding kills.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.