Sandbox: Breast Abscess
Synonyms and keywords: Mammary abscess, Zuska's disease, lactiferous fistula.

# Overview

# Historic Perspective
In 1841, Dr. Jonathan Toogood reported a case of breast abscess out of only 5 cases at this time.

# Classification
Breast Abscess may be classified according to anatomical location and lactation state of the patient into subtypes.
- Anatomical location: subcutaneous, subareolar, interlobular, central and retromammary
- Lactation state: Lactational and Non-Lactational.

# Pathophysiology
Following untreated mastitis, breast abscess could occur. 
Breast abscess is usually caused by staphylococcus aureus bacterial infection to an injured breast skin. Staphylococcus aureus could form abscess by secretion of several killing agents like enzymes and toxins. In a reaction to these bacterial substances, assembled white blood cells in this tissue produces anti-bacterial anti-bodies that help in killing the bacteria. However, these cells cause damage to the soft tissue contributing in the abscess formation. 
As the breast abscess is the complicated form of mastitis, the pathophysiology is mostly like the mastitis pathophysiology.

## Pathogenesis
Breast abscess is the result of underlying inflammation (mastitis) in the breast skin. Injury may happen either during the lactation process from the infant or in the non-lactaion state of the patient as a cracking in the breast skin. This injury accelerates the entry of the causative bacteria which by its role form the abscess. In neglected cases, there may be necrosis in the abscess location leads to fibrosis, scarring and nipple retraction.
- Lactational:
Injured breast skin allows the entrance of the bacteria to the mammillary ducts. This bacteria can be from the infant or the mother herself. Overproduction of the breast milk with no flow to the infant forms an opportunistic field for the bacteria to cause infection.
Breast Duct Ectasia: metaplastic change of the duct cells can cause duct ectasia. This change causes widening of the ducts lining which leads to thickening of the ducts and obstruction. The ducts become filled with fluid which leads to nipple discharge and infection by the entrance of the bacteria and can form pus and abscess as a final result. 
- Injured breast skin allows the entrance of the bacteria to the mammillary ducts. This bacteria can be from the infant or the mother herself. Overproduction of the breast milk with no flow to the infant forms an opportunistic field for the bacteria to cause infection.
- Breast Duct Ectasia: metaplastic change of the duct cells can cause duct ectasia. This change causes widening of the ducts lining which leads to thickening of the ducts and obstruction. The ducts become filled with fluid which leads to nipple discharge and infection by the entrance of the bacteria and can form pus and abscess as a final result. 
- Non-Lactional:
Non lactational breast abscess is less common than lactational form. It can be subgrouped into central, peripheral and skin associating.
Cracking in the skin will overtly help the bacteria to enter and form the abscess.
- Non lactational breast abscess is less common than lactational form. It can be subgrouped into central, peripheral and skin associating.
- Cracking in the skin will overtly help the bacteria to enter and form the abscess.

## Associated Diseases
There is no associated diseases with breast abscess.

# Causes
Breast abscess is a bacterial infectious disease that is caused by many bacterial pathogens and it may also be caused by fungi mostly common candida through the infant mouth. It is almost caused by the same pathogens causing mastitis. To understand the common species causing breast abscess we can classify them into gram +ve and gram -ve bacteria. 

# Differentiating Breast abscess from other Diseases
Breast abscess should be differentiated from other diseases that cause swelling in the breast skin. These diseases are like mastitis, inflammatory breast cancer, galactocele, plugged duct, Mondor's syndrome and fibroadenoma. 
Other differential diagnosis of breast abscess can include:
- Cystosarcoma phyllodes
- Breast cyst
- Breast carcinoma
- Lymphangioma
- Hemangioma
- Lipoma

# Epidemiology and Demographics
Breast abscess is a rare disease that may occur due to improper treatment of the mastitis. There is no significant prevalence concerning the abscess.

## Incidence
- The incidence of breast abscess is 3,000-11,000 per 100,000 of patients with mastitis.
- The incidence of breast abscess is only 100-3,000 per 100,000 of the puerperal patients. 

## Age
- Patients of all age groups may develop breast abscess.
- Breast abscess is more common observed in the infants and the young more than the elder.
- It is common in neonates with mastitis as approximately 50 percent of the neonatal patients with mastitis can develop breast abscess.

## Gender
Breast abscess occurs commonly in women. It is very rare to be developed in men.

## Race
Breast abscess is more prevalent in the african american race.

# Risk Factors

## More common risk factors
- The most important risk factor of breast abscess is trauma.Trauma increases the possibility of the abscess formation as it facilitates the entrance of the causative bacteria into the soft tissue. Trauma can take place by different ways like shaving subareolar hair, piercing of nipple, infant's mouth during breastfeeding and picking acne lesions.
- Smoking: increases the chances of abscess recurrence.
- Obesity
- Diabetes mellitus
- Duct ectasia of the breast.
- Local skin infection

## Less common risk factors
These risk factors are related more to the non-lactational breast abscess.
- Insect bites
- Increasing age
- Surgical treatment: increases recurrence rate of the abscess.

# Natural history, complications and prognosis

## Natural History
There is no significant natural history regarding the breast abscess. However, the abscess generally if not treated it will burst around its site or necrosis will take place.

## Complications
Complications that can develop in cases of breast abscess are:
- Inflammatory breast cancer
- Milk fistula
- Antibioma

## Prognosis
Breast abscess prognosis is good with treatment but it has a high recurrence rate. In non lactational abscess has a high chance of recurrence (more than 50% of the cases).. In the lactational abscess the chance of recurrence is around 35-50% of the cases.

# Diagnosis

## History and Symptoms
Breast abscess can be noticed first by the patient like a breast mass or lump. The patient usually has current breast infection(mastitis) or history of the infection. 
In order to get precise diagnosis of breast abscess, these items should be put in consideration: 
- Local painful breast lump
- History of mastitis
- Nipple discharge
- Risk factors of the breast abscess like trauma, duct ectasia or insect bites.
- If lactating patient: breast-feeding history
- If non-lactating history: diabetic history

### Most common symptoms
Breast abscess has a typical abscess symptoms which are:
- Fever and fatigue
- Redness
- Warmth
- localized swelling
- Breast skin induration

### Less common symptoms
- Nipple discharge
- Fistula
- Mass in the breast

## Physical examination
Patients with breast abscess are remarkable for the breast tenderness, swelling, redness and warmth of the skin.

## Laboratory findings
Breast abscess diagnosis depends only on the clinical manifestations of the abscess not the laboratory findings. However, a culture could be taken from the milk and the pus just to decide the antibiotics needed for the treatment.

## Electrocardiogram
There is no significant changes in the EKG of breast abscess patients.

## Chest X ray
There is no x-ray changes in the chest of breast abscess patients.

## CT Scan
CT scan is not used to diagnose the breast abscess. However, it can be performed to exclude other diseases like breast cancer.

## Ultrasound
- Ultrasonography is an important imaging approach for diagnosis of the breast abscess. It is mainly used to differentiate between the different diseases causing breast lumps. It is also used in abscess needle aspiration guiding.
- Breast abscess on chest ultrasonography appears like medium sized collections with not well defined margins and may have some areas with increased density.
- There is no vascularity in the US image.

## Other Imaging Findings
Mammography is not indicated to be used in diagnosis of the breast abscess. However, it is strongly recommended in these cases to be used to differentiate between the breast abscess and other breast diseases and cancer.

# Treatment
Breast abscess treatment regimen includes both abscess drainage (surgically and by aspiration) and antibiotic medical therapy.It is treated mainly surgically through abscess drainage and suction.The patient should be referred immediately to the breast surgeon to start the abscess drainage.

## Medical therapy
Medical treatment is important alongside the surgical treatment.Breast abscess is treated with antibiotic medical therapy as a supportive line to the surgical measures and to prevent the abscess recurrance. The choice of the antibiotic medications depends on the pathogen type however, the high possibility of the pathogen to be staphylococcus aureus leads to start the antibiotic medications before the result of the discharge culture..

### General measures
Breast abscess is painful so providing analgesics like profen is indicated to the patients. In order to relieve the pain and decrease the edema, breast support is indicated also.

### Lactaitonal breast abscess
- Preferred regimen: Flucloxacillin 500 mg BID if there is no allergy to penicillin.
- Preferred regimen: Dicloxacillin 500 mg PID if there is no allergy to penicillin.
- Alternative regimen: Erythromycin 500 mg BID in case of penicillin allergy.

### Non lactational breast abscess
- Preferred regimen: Co-amocyclave 375 TID if there is no allegy to penicillin.
- Alternative regimen: Combination of Erythromycin 500 mg BID and Metronidazole 200 mg TID in case of penicillin allergy.

## Surgery
The first line of breast abscess treatment is US guided needle aspiration and surgical drainage of the abscess.

### Aspiration
Needle aspiration is used particularly in the small and medium sized abscesses. It can be US-guided aspiration or without the US. Local anesthesia is required in order to reduce the pain of the abscess location. It is preferred in case the breast skin is not affected with the abscess. This process is preferably done two or three times to ensure that the abscess location is completely clean from all the pus.

### Surgical drainage
If there is no response after several times of needle aspiration to the abscess then surgical drainage is the best line of treatment in this case. If there is no response to the surgical drainage then the last line of treatment is to do excision to the lactiferous duct of the affected breast.
Abscess surgical drainage is the best line of treatment in these cases:
- The skin is included in the abscess.
- Unresponsive abscess to medical therapy or the aspiration.
- Large abscesses.
Video explaining how the breast abscess is drained: 

## Prevention
Breast abscess prevention depends on the prevention of the risk factors and the patients hygiene specially in the lactating patients:
- Patients should be taught to keep the nipple area clean especially if there is injury
- Complete emptying of the breast after feeding the infant in order to prevent milk stasis
- Keep the infant in a good contact during breastfeeding
- Avoid dehydration in the nipple and the surrounding to prevent cracking
- Keep the infant clean
- Infection control through washing hands frequently
- It is advised to continue breastfeeding after the drainage to prevent recurrence and help healing.