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.
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
- Breast ultrasound: dilated subareolar ducts
- Mammography: dilated, tortuous subareolar ducts, branching calcifications
- 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. 
Consider surgical duct excision for patients with: 
- Nipple discharge 
- Other persistent symptoms
- Nondiagnostic biopsy