Editing Breast abscess

Localised collection of inflammatory exudate in the breast tissue.

== '''Risk factors''' ==

* Obese
* Smokers
* Maternal age >30 years
* First pregnancy
* Problems with breastfeeding

== '''Pathophysiology''' ==

* Complication of mastitis (cellulitis with breast parenchymal inflammation and swelling)
* Mastitis can develop in two ways
** Lactational infections
*** Something inhibits milk drainage (nipple trauma and oedema, dehydration and inspissation, oversupply, feeding difficulties, rapid weaning, maternal malnutrition)
*** Collections of stagnant milk
*** Organisms infiltrate through nipple and grow in the stagnant milk
** Chronic subareolar infections associated with duct ectasia (also called periductal mastitis/non-lactational infections)
*** Risk factors
**** Smoking (majority of patients - 89% in one study)
**** Diabetes
*** Pathophysiology
**** An inflammatory condition of the subareolar ducts
**** Likely caused by toxins, microvascular damage by lipid peroxidases, and altered bacterial flora
**** Duct ectasia and squamous metaplasia ensue, causing stasis of ductal secretions
**** Secondary infections and abscess formation
***** Most often mixed infections with anaerobes and skin flora
***** Infections frequently recur, because the underlying duct is diseased
**** Inflammatory changes can eventually lead to retraction or inversion of the nipple, subareolar masses, and chronic fistula to peri-areolar skin

== '''Classification''' ==

*
* Central usually due to periductal mastitis
* Peripheral less common, sometimes associated with underlying disease states or trauma

== '''Microbiology''' ==

* Mostly Staph aureus
* Patients with recurrent abscesses have an increased incidence of mixed flora and anaerobic infection
* Culture of breast milk can guide antibiotics if aspirate is not available
* Blood cultures only helpful if there is evidence of systemic sepsis

== '''Differential diagnosis''' ==

* Lactating women:
** Plugged duct
** Galactocoele - soft cystic mass that won't be tender. Can diagnose based on aspiration of milk.
* All women:
** Inflammatory breast cancer. Consider this if the infection does not resolve with appropriate treatment (one week antibiotics), or in non-lactating post-menopausal women without any precipitating factors or systemic signs of infection. Skin thickening due to oedema, erythema, peau d'orange appearance.
*** Investigate with imaging and a punch biopsy of affected skin and possibly core biopsy from deeper masses - if this is negative, doesn't exclude the diagnosis though. May need MRI.
** Idiopathic granulomatous mastitis (IGM)
*** Rare chronic inflammatory breast disease with unclear cause
**** Possibly related to corynebacterium infection
*** Non-caseating granulomas and microabscesses confined to a lobule
*** Painful mass associated with fistulas, abscesses, inflammatory changes
*** No association with smoking
*** Clinical presentation and radiological findings similar to breast cancer
*** Don't excise it - often followed by persistent wound discharge and failure to heal
*** Steroids and immunomodulators have been used, but variable efficacy
*** The condition tends to resolve spontaneously over 6-18 months, so best to treat supportively, especially treating the episodes of infection and abscess formation, through as minimal an intervention as possible

== '''Management''' ==

* Approach
** Antibiotics and frequent emptying of the breast (step up approach)
* Simple advice:
** Continued milk draining is important - essentially drains the abscess, resulting in reduced duration of symptoms and improved outcome
** Not a contraindication to breastfeeding on that side
** Warm soaks are helpful for mastitis
* Antibiotics
** Flucloxacillin 
** Consider anaerobic organisms if subareolar location, hidradenitis suppuritiva, recurrent abscess - Augmentin DF would be a good option for a non-lactational infection
** MRSA is possible but uncommon
* Percutaneous drainage
** Appropriate first-line when skin is viable
** Repeat every 2-3 days until no collection remains or the fluid aspirated is serous
** Few abscesses require more than 2-3 drainages
** Pigtail catheters can be placed if desired, but not normally necessary
** Technique
*** Can be USS-guided if desired
*** First try with a 21 gauge needle and inject LA + adrenaline
*** If pus is too thick, use a 19 or 17 gauge needle
*** Wash out cavity until clear
*** Irrigate with LA solution
** Risk factors for failure of aspiration:
*** Abscess >5cm in diameter
*** Unusually large volume of aspirated pus
*** Delay to treatment
* Surgical drainage
** Indications
*** Compromised overlying skin (ischaemia/pressure necrosis) - see bottom for examples of compromise
*** Skin overlying abscess is very thin and shiny, or if it appears like the abscess is about to burst through the skin
*** Not responsive to percutaneous aspiration
*** Repeated infections requiring excision of subareolar duct complex, and sometimes the entire NAC
** Technique
*** See separate topic
* Follow-up
** MMG and USS six weeks post-presentation for all women to exclude IBC

== '''Complications''' ==

* Recurrence
* Mammary duct fistula
** Communication between major subareolar duct and the skin, usually in the periareolar region
** Can occur after I+D of a central abscess or after spontaneous drainage
** Seen in smokers, recurrent abscesses
** Fistulotomy or fistulectomy can be done. Fistulectomy gives a better result - see topic under 'breast operations'.
* Milk fistula
** Tract between skin and lactiferous duct after surgical intervention
** Milk drains through skin
** Mainly occurs with big incisions or large drains
** Usually resolves spontaneously
** If persistent, usually resolves with cessation of lactation - wean from that breast and only nurse from other side
* Antibioma
** When treated with antibiotics but not drained, it can become a sterile collection - firm, painless, smooth swelling
** Aspirate it, don't excise it



^ischaemic skin

^pressure necrosis

^thinned skin
[[Category:Breast]]
[[Category:Intern education]]