6 Nipple discharge

Definition
Any fluid (which may be physiological or pathological) emanating from the nipple.
KEY POINTS
• Milky discharge is rarely pathological.
• Purulent discharge is usually benign.
• Bloody discharge is often associated with neoplasia.
• If a lump is present, always investigate ‘for the lump’ rather than ‘for
the discharge’.
Differential diagnosis
Physiological discharges
Milky or clear
• Lactation.
• Lactorrhoea in the newborn (‘witches’ milk’).
• Lactorrhoea at puberty (may be in either sex).
Pathological dischargcs
Serous yellow-green
• Fibrocystic disease: cyclical, tender, lumpy breasts.

• Mammary duct ectasia: usually multiple ducts, intermittent, may be associated with low-grade mastitis.
Bloody
• Duct papilloma: single duct, ?retro-areolar, ‘pea-sized’ lump.
• Carcinoma: ?palpable lump.
• Mammary duct ectasia: usually multiple ducts, intermittent,
may be associated with low-grade mastitis.
Pus ± milk
• Acute suppurative mastitis: tender, swollen, hot breast, multiple ducts discharging.
• Tuberculous (rare): chronic discharge, periareolar fistulae,
‘sterile’ cultures on normal media.

KEY INVESTIGATIONS
• MC+S: acute mastitis, TB (Lowenstein—Jensen medium, Ziehl—Neelsen
stains).
• Discharge cytology: carcinoma.
• Mammography: tumours, fibrocystic disease, ?ectasia.
• Ductal excision: maybe needed for exclusion of neoplasia.