A 53-year-old woman presents with unilateral bloody nipple discharge. Mammography is normal. What is the most definitive next step to establish histology?

• A. Duct excision
• B. MRI
• C. Cytology
• D. Observation

Answer: (A)

Unilateral bloody nipple discharge with a normal mammogram raises concern for intraductal pathology, and the definitive way to establish histology is to obtain tissue from the ductal system. Duct excision (major duct excision or microdochectomy) removes the involved duct and any intraductal lesion, allowing complete histologic evaluation. Cytology from the discharge often misses pathology because it lacks architectural context and has limited sensitivity. Imaging like MRI can detect abnormalities but does not provide tissue for histology. Observation would risk missing a malignancy or premalignant process. Therefore, duct excision is the best step to obtain a definitive histologic diagnosis and guide management.