Mammary Duct Ectasia

A benign condition characterised by dilation and, over time, inflammation and fibrosis of the major subareolar milk ducts. It typically occurs in perimenopausal and postmenopausal women.

It is a common cause of nipple discharge and, in some cases, a palpable, ill-defined subareolar mass or nipple retraction.

Careful clinical distinction is required from periductal mastitis and from malignancy. Periductal mastitis is a closely related but distinct condition with overlapping features, sometimes considered part of the same disease spectrum. Nipple retraction and subareolar induration can closely mimic malignant change.

Pathophysiology

• Progressive dilation of the major subareolar ducts, with accumulation of thick, stagnant secretions in the dilated system, produces the characteristic clinical findings.
• The cause of the initial ductal dilation remains incompletely understood. It is believed to reflect age-related changes in ductal and periductal tissue.
• Stagnant, retained secretions can trigger a secondary inflammatory response (periductal mastitis, a closely related condition sometimes considered to lie on the same disease spectrum).
• Chronic, recurrent inflammation causes progressive periductal fibrosis. Fibrotic tethering of the overlying nipple and areolar tissue produces the nipple retraction seen in more established or advanced disease.
• The condition is distinct from periductal mastitis, though some features overlap. Periductal mastitis is more classically associated with younger women and has a stronger, well established association with cigarette smoking. Some clinical overlap and shared pathophysiology between the two is recognised.

• Nipple discharge is a common, characteristic presenting feature. It is typically thick, sticky and variable in colour (clear or white through to green, brown or, in some cases, blood-tinged), and often bilateral from multiple ducts.
• A palpable, ill-defined, sometimes tender subareolar mass or thickening may be present, reflecting dilated, inflamed ductal tissue.
• In more established disease there may be nipple retraction. In this condition it is typically slit-like and often reflects a gradual, longstanding process, rather than the more acute, progressive retraction characteristic of malignancy.
• Periareolar pain and tenderness are particularly relevant where periductal inflammation is present. Secondary infection can produce more significant acute inflammatory changes and, occasionally, abscess formation.
• The condition typically occurs in perimenopausal or postmenopausal women. This distinguishes the typical presentation from periductal mastitis, which more characteristically affects younger women, though some overlap in age of presentation is recognised.

• Clinical overlap with malignancy, particularly nipple retraction and a palpable subareolar mass, makes triple assessment essential for confident diagnosis. This applies especially in the typically older age group, where malignancy risk is higher.
• Mammography and ultrasound may show dilated, tubular structures corresponding to the affected ducts and, in some cases, associated calcification.
• Imaging alone cannot always confidently exclude malignancy because of overlapping features. Histological or cytological confirmation is frequently required.
• Where nipple discharge is the predominant presenting feature, cytological examination of the discharge, with the broader structured diagnostic approach to nipple discharge, supports evaluation.
• Core needle biopsy or, where surgical excision is undertaken, formal histopathological examination gives definitive confirmation where clinical or imaging findings do not provide sufficient reassurance in isolation.

• Reassurance and observation is appropriate for women with mild, non-troublesome symptoms once malignancy has been confidently excluded by full assessment. The natural history is generally benign, though sometimes chronic and recurrent.
• Symptomatic management, including simple analgesia for discomfort and warm compresses, gives supportive relief during episodes of more significant inflammation.
• Antibiotic therapy is indicated where secondary infection is present, following broadly similar principles to those for periductal mastitis. Any associated abscess requires incision and drainage.
• Surgical excision of the affected, symptomatic subareolar ducts may be considered. Options are microdochectomy or total duct excision, according to the pattern of ductal involvement.
• Indications for excision are persistent, troublesome symptoms not controlled by conservative measures, diagnostic uncertainty not resolved by standard non-surgical assessment, or recurrent infection that is a significant ongoing concern.
• Patient education is part of management. Discuss the benign nature of the condition, the findings that led to the diagnosis, and the confidence with which malignancy has been excluded.