Mastitis refers to the inflammation of the breast which is sometimes, but not always, accompanied by an infection and abscess. It most commonly occurring in the puerperal period - the period up until 6 weeks after delivery of the placenta where the maternal anatomy returns to its pre-pregnant state. However, it can occur in women who are not lactating as well.
Breast abscess is a complication of mastitis but is not always preceded by mastitis. Ultimately it is a collection of pus within the breast which needs drainage and antibiotics for resolution.
🔢 Pathophysiology and classification
We can classify mastitis as 2 main types:
- Lactational/puerperal mastitis - if related to breastfeeding. This is primarily due to stasis of milk which results in an inflammatory response that can sometimes lead to infection. When combined with trauma to the nipple (due to
- Non-lactational mastitis - if unrelated to breastfeeding. Occurs in smokers. It can be sub-classified by it’s location:
- Central/subareolar - often secondary to periductal mastitis or, rarely, duct ectasia.
- Peripheral - associated with diabetes rheumatoid arthritis, trauma, corticosteroid use, granulomatous mastitis.
- Childbirth
- Oral contraceptives
- Trauma
- Hyperprolactinaemia
- TB
- Sarcoidosis
- Diabetes mellitus
A rare inflammatory breast disease affecting pre-menopausal women usually. It is believed to be autoimmune in aetiology and is idiopathic or sometimes follows corynbacterium infection.
Other risk factors for granulomatous mastitis include:
🦠 Causative agents
- 🥇 Staph. aureus (gram positive)
- Streptococcal spp. (gram positive)
- Enterococcus spp. (gram positive)
- Bacteroides spp. and other anaerobic bacteria
Simple penicillins (such as flucloxacillin) are likely to be effective against gram positive bacteria, but with anaerobes they are not as effective. Co-amoxiclav covers anaerobic bacteria and metronidazole of course.
If allergic to penicillins, clarithromycin/erythromycin may be used.
⚠️ Risk factors
- Smoking
- Nipple damage (eczema, piercings, candida infection)
- Breast cancer or other underlying breast abnormalities as it can cause poor drianage → infection.
- Immunosuppression
- Poor hygiene
😷 Presentation
It is usually an acute onset of puerperal mastitis with infection. This may present as:
- Fluctuant lump (able to move fluid within the lump during palpation)
- Localised pain & tenderness
- Purulent discharge
- Nipple changes
It is usually unilateral.
- Hardening of breast tissue or skin
- Warmth redness, swelling.
As with any infection there may be systemic symptoms such as fever, malaise, or signs of sepsis.
🔍 Investigations
- It is usually made clinically with history and examination.
- USS may aid diagnosis
Breast milk culture should be sent in cases of lactational mastitis if it is:
- Severe, recurrent or unusual presentation
- The infection is likely to be hospital-acquired.
- Deep, burning breast pain is felt as this may indicate a ductal infection.
🧰 Management
⭐️ The most definitive management is incision and drainage with ultrasound-guided needle aspiration.
Women should continue breastfeeding if possible, and this does includes feeding from the affected breast. If it is too difficult or painful, women should be advised to manually express the milk until breastfeeding is possible once more.
- Oral antibiotics are indicated if symptoms have not improved after 12-24 hours and milk removal has been trialled, or if there is a positive breast milk culture.
- 🥇 Flucloxacillin is the first-line option.
- 🥇 Erythromycin/clarithromycin is an alternative if allergic to penicillin.
- 🥈 Co-amoxiclav is the second-line choice.
- Analgesia may aid the mastitis pain.
- Broad-spectrum antibiotics should be prescribed to all women with non-lactational abscess.
- Co-amoxiclav
- Erythromycin/clarithromycin + metronidazole
⛔️ Complications
- Mammary duct fistula - when the skin has a connection to the subareolar breast duct
- Sepsis
- Scarring