Non-puerperal mastitis

Definition

• Inflammation of the breast arising independently of lactation, distinguished as nonlactational (non-puerperal) mastitis from the lactational (puerperal) form.

Classification

• Forms include periductal mastitis, nonlactational infectious mastitis, idiopathic granulomatous mastitis and tuberculous mastitis.
• Recurrent subareolar abscesses with mammary duct fistulas are called Zuska disease after the original description of 1951.
• Whether duct ectasia and periductal mastitis are stages of the same disease or separate entities is debated.

Occurrence & epidemiology

Epidemiology

• Periductal mastitis mainly affects women under 30 years of age or perimenopausal women; granulomatous lobular mastitis usually occurs in women of childbearing age between 30 and 40 years, often within a few years after childbirth.

Aetiopathogenesis

Aetiology and pathogenesis

• Smoking is the best-documented risk factor for periductal mastitis: squamous metaplasia of the ductal epithelium leads to keratin production, duct obstruction, stasis and secondary bacterial infection.
• Nipple inversion promotes periductal mastitis through impaired outflow of secretions; nonlactational breast infections are also associated with obesity and diabetes mellitus.
• The most common pathogen is Staphylococcus aureus, followed by coagulase-negative staphylococci; mixed infections with anaerobes are frequent, especially in chronic or recurrent abscesses, and more so in heavy smokers.

Clinical features

Inflamed breast

• Puerperal mastitis characteristically presents with a wedge-shaped erythema, warmth, fever, and chills, most often caused by Staphylococcus aureus.
• Non-puerperal mastitis has a frequently chronic-recurrent course, often with duct ectasia and a history of smoking.

• Typical features are intermittent or noncyclical breast pain, purulent or serous nipple discharge, nipple retraction or inversion and a subareolar mass.
• Subareolar abscesses may rupture spontaneously, recur and progress to periareolar cutaneous fistulas.

Diagnosis

• Ultrasound is the initial examination to confirm inflammation and identify abscesses; mammography has a limited role in the acute phase.
• In abscesses, atypical course, uncertain diagnosis or recurrence, tissue sampling serves to exclude malignancy and uncommon pathogens, as noninfectious forms can mimic cancer; granulomatous lobular mastitis is confirmed histologically after exclusion of other causes.

Keep learning in the app

Further reading (selection)

1. Identification of periductal mastitis and granulomatous lobular mastitis: a literature review (Ann Transl Med 2023, PubMed Central)
2. MSD Manual Professional: Breast Masses
3. DocCheck Flexikon, Mastitis non-puerperalis

Cross-references