Mastitis and abscesses 

So, first day of surgery and after a ward round I sat in on a breast clinic. I felt a malignant breast lump (surprisingly obvious), saw a lady who was pleasantly cheerful about her upcoming breast cancer surgery, another who had scars from axillary breast tissue removal (seems super painful), a few post-cancer treated ladies, and two cases of mastitis.

One lady had idiopathic granulomatous mastitis- i.e. We have no idea what is causing your mastitis. TB (not just a lung disease) tests came back negative and so did sarcoidosis, both associated with granulomatous disease. She was pretty unhappy with everything but trying to keep in good spirits because recurrent breast infections can’t be very pleasant. She had lots of scars from previous abscess drainage.

The second lady presented with lactating mastitis, baby and all. Cute baby, not so cute Staphylococcus aureus colonising his mouth and infecting his milk machine by inappropriate latching.


Mastitis & Breast Abscesses

DImage result for anatomy of the breastefinitionMastitis is inflammation of the breast, with or without infection. Mastitis with infection may be lactational (puerperal) or non-lactational (non-puerperal). A breast abscess is a localised area of infection with a walled- off collection of pus, which may or may not be associated with mastitis.

Aetiology/ risk factors:

Lactational mastitis/ abscess:

-due to acute staphylococcal (S.aureus) infection of mammary ducts associated with milk stasis.

-Tend to start soon after starting breast-feeding and on weaning, when incomplete emptying of breast results in stasis and engorgement.

Non-puerperal mastitis/ abscess:

-often recurrent

– associated with mammary duct ectasia (central ducts become blocked and dilated with secretions → leakage occurs into periductal tissue  →  inflammatory reaction, prone to infection→periductal mastitis.)

-associated with wound infections after breast surgery, diabetes and steroid therapy

-associated inflammatory breast cancer should be excluded

S.auereus and mixed anaerobes, often enterococci or Bacteroides spp. TB and actinomycosis are rare causes.

Non-infectious mastitis includes idiopathic granulomatous inflammation (very rare) and other inflammatory conditions e.g. foreign body reaction (nipple piercing, breast implant). May result from underlying duct ectasia.

 

-Risk factors: poor breastfeeding technique, lactation, milk stasis, nipple injury, previous mastitis or breast abscess, removing areolar hair, breast cancer, nipple piercing, breast implants, skin infection, immunosuppression, cigarette smoking, breast trauma etc.

Epidemiology:

-Global prevalence of mastitis in lactating women is ~1-10%. Duct ectasia occurs in 5-9% of non-lactating women.

-Much more common in women

-Breast infection typically affects women 15-45 yrs, infants < 2 months and adolescent girls. Women > 30 yrs, have a higher risk of mastitis, possibly due to milk stasis.

Symptoms:

breast discomfort and pain

-may feel unwell, feverish, malaise, myalgia

-decreased milk outflow

Signs:

-breast swelling and tenderness

-overlying skin may be inflamed, erythema

-breast firmness

-abscess presents as acute, severe localized pain,  associated with hot, tender swelling and redness in area of the breast  (lactational- tend to be peripheral, non-puerperal- tend to be sub-areolar)

-nipple may reveal cracks or fissures

-in non-puerperal cases: may be evidence of scars or tissue distortion from previous episodes (e.g. drainage incisions) or signs of ductal ectasia: nipple retraction, lump, green/brown/ bloody nipple discharge

-yellow/ green nipple discharge (seropurulent- watery pus) (uncommon- usually associated with duct ectasia)

-breast mass (uncommon- may occur with tender area of localised mastitis or breast abscess)

-lymphadenopathy, tender axillary lymph nodes (uncommon)

-pyrexia, tachycardia

Investigations:

-Breast U/S, especially to diagnose abscess

-Diagnostic needle aspiration drainage (purulent fluid indicates abscess)

Cytology of nipple discharge or sample from fine-needle aspiration (demonstrate malignancy or infection)

-Aspirate (or milk, discharge, tissue biopsy) for microscopy, culture and sensitivity (positive culture indicates infection)

Histopathological examination of biopsy tissue (demonstrate infection, granulomatous inflammation or malignancy)

Other tests to consider:

-pregnancy test

-blood culture and sensitivity (look for systemic infection)

-mammogram

-milk for leucocyte count and bacteria quantification

-culture from swab/aspirate from infant’s and mother’s oral pharynx and nasal cavity

-Full Blood Count (leucocytosis with infection, neutropenia with immune suppression)

-tuberculin skin test/ Elipsot test for TB

Management:

-Primary prevention: good breastfeeding habits, proper nipple hygiene, sterile equipment for nipple piercing

-may need analgesia e.g. NSAIDS- DICLOFENAC

-oral antibiotics

-lactational: including flucloxacillin

-non-puerperal: including metronidazole or co-amoxiclav

-Breast-feeding should continue on non-affected breast and the affected side emptied either manually or with a breast pump to prevent milk stasis.

-For abscesses repeated needle aspiration  under local anaesthetic. Open incisions and drainage may be necessary (e.g. for large > 5cm abscess) but often avoided, especially in lactational abscesses.

-With non-puerperal cases, after the infection has settled the involved duct system can be surgically excised.

Complications: slow wound healing, difficulties in breast-feeding, poor cosmetic outcome, mammary fistula formation (communication of duct with skin surface), skin undergoes necrosis (rare)

Prognosis: 

-if untreated, breast abscess will spontaneously discharge onto skin surface

-non-puerperal abscesses tend to recur

 

References: Cheese and Onion (surgery version), Rapid Surgery, BMJ Best Practice
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