Mammary duct ectasia

Mammary duct ectasia is a chronic inflammatory condition characterized by dilatation of the terminal (subareolar) lactiferous ducts, with a peak incidence in women between 40–50 years of age. Although often asymptomatic, mammary duct ectasia may manifest with unilateral or bilateral nipple discharge, nipple inversion, or a subareolar mass. The diagnostic workup is based on the age-appropriate evaluation for pathological nipple discharge and/or a palpable breast mass. A biopsy may be required if imaging is inconclusive or depicts features concerning for malignancy. The typical histopathological features of duct ectasia include periductal inflammation, luminal secretions with/without inflammatory infiltrate, and foamy histiocytes. As most cases resolve spontaneously, expectant management is usually appropriate. Surgical excision of the affected duct may be considered for symptomatic control.

• Most common in perimenopausal women
• Peak incidence: 40–50 years

Epidemiological data refers to the US, unless otherwise specified.

Inspissated luminal secretion → stasis → periductal inflammation → fibrous obliteration

• Often asymptomatic
• Unilateral or bilateral nonmilky gray, greenish, or bloody discharge
• Nipple inversion
• Firm, tender subareolar mass may be present (may mimic breast cancer)
• Noncyclic mastalgia

Mammary duct ectasia is the most common cause of greenish nipple discharge.

Approach ^[1][2]

• Pathological nipple discharge and/or palpable breast mass: Perform age-appropriate breast imaging.
  • Age < 30 years: breast ultrasound
  • Age ≥ 30 years: mammography with adjunctive breast ultrasound
  • See also “Palpable breast mass” and “Diagnostic approach to nipple discharge” for further detail.
• Imaging findings concerning for malignancy : biopsy

Imaging ^[3]

• Breast ultrasound: dilated subareolar ducts
• Mammography: dilated, tortuous subareolar ducts, branching calcifications

Biopsy ^[3][4]

• Periductal inflammation and/or fibrosis
• The ductal lumens may be obliterated or filled with inspissated secretions and inflammatory cells.
• Foamy histiocytes are characteristically present within the inflammatory infiltrate.

• Expectant management is usually sufficient as most cases resolve spontaneously. ^[1][5]
• Consider surgical duct excision for patients with: ^[2]
  • Nipple discharge ^[1][2]
  • Other persistent symptoms
  • Nondiagnostic biopsy