By Drs Ibraheem M Tunau, Nora Abdulaziz and Anne Merrigank
Breast abscess is a painful and potentially destructive condition. It is a surgical emergency. It is an acute, painful condition that may cause breast destruction and may discourage breastfeeding. It is most common amongst pre-menopausal and lactating women in whom up to 80 per cent of breast abscesses occur. Breast abscess in non-lactating women is not as common but significant, because it is more likely to be chronic and rarely may be a sign of breast cancer.
GPs in Ireland have reported an increase of patients presenting with breast abscess despite Ireland’s abysmal rate of breastfeeding (1:450). This is probably due to the increase in number of immigrants in Ireland within the last decade. A recent study in the Coombe Hospital revealed more non-Irish national women than Irish women attempted breastfeeding.
We do not have the exact figures for breast abscess in Ireland, but it is important to make an early diagnosis and provide immediate and appropriate treatment.
Diagnosis of breast abscess usually starts as acute mastitis which, if untreated, progresses into an abscess. Abscess must be differentiated from mastitis, in which there is inflammation without pus. Early recognition of acute mastitis and prompt use of antibiotics prevents the development of an abscess. The incidence of sporadic mastitis is 2-10 per cent in lactating and less than 1 per cent in non-lactating mothers. Breast abscess develops in 5-11 per cent of women with mastitis.
A breast abscess can usually be managed without surgery, with simple needle aspiration, antibiotics and analgesia. This could be done in GP surgeries in patients with an obvious diagnosis. Some patients require ultrasound guidance for drainage, while a minority will need open surgical drainage. All cases of acute breast abscess should be referred to the next available breast clinic usually within 48 hours.
Breast abscess may be classified into primary or secondary (Table 1). Primary breast abscess is broadly divided into lactational and non-lactational and these typically occur in women aged 18 to 50 years. These abscesses could be central/periareolar or peripheral. Primary abscess may also occur in infants less than two months of age (neonatal breast abscess). Secondary breast abscess is mostly due to an underlying skin disorder e.g. sebaceous cyst or hidradenitis suppurativa.
The underlying causative organism in most breast abscesses is Staphylococcus aureus. Methicillin resistant S. aureus (MRSA) has been isolated in some hospital-acquired infections. Staphylococcus epidermidis and streptococci are occasionally isolated especially in the lactating woman. Enterococci, anaerobic streptococci and bacteroides species may be found in the non-lactating women.
In the lactating woman, infection usually occurs through an irritated or fissured nipple, especially where there are nipple cracks or skin abrasions. This may be precipitated by milk stasis due to plugging of the lactiferous ducts. Necrosis may also develop; producing fibrosis, scars and nipple retraction, a presentation that can mimic an underlying breast carcinoma.
There is a strong association of cigarette smoking with breast abscess in non-lactating women and it may predispose to anaerobic breast infection and the development of mammary fistulae. Also, in non-lactating women, abscess most commonly affects the skin of the lower half of the breast and often recurs in women who are overweight, have large breasts or have poor personal hygiene.
Complications of breast abscess include cessation of breastfeeding (in lactating women), bacteraemia and sepsis, destruction of breast tissue with loss of large volume resulting in disfigurement, recurrent or chronic infection, scarring and mammary fistulae.
Patients with acute mastitis present with pain, redness and swelling of the breast. Non-specific systemic symptoms such as fever, chills, fatigue and body aches may occur. Risk factors include maternal fatigue, poor nursing technique, nipple trauma or dryness. Women with non-lactational breast abscess are more likely to smoke.
Characteristic signs are pyrexia (usually high grade: 39-40 degrees centigrade), localised erythema, palpable heat over the area and tenderness. There may also be an area of induration. While leucocytosis is common, axillary lymphadenopathy is uncommon.
Patients who have developed an abscess will have an area of induration and often a firm mass in the breast, which may be fluctuant. The skin over this may be red, thin and shiny. Rarely, there may be spontaneous drainage from the mass or nipple. The nipple may be inverted or retracted. Sometimes an early sign may be a poor response to the antibiotic treatment of mastitis.
Lactational breast abscesses are more likely to be peripheral and more commonly in upper outer quadrants. Non-lactational abscesses are more commonly central/subareolar or lower quadrants. In the central breast, a fluctuant area may be hard to palpate. Peripheral non-lactating abscesses are less common than periareolar non-lactating abscesses and are often associated with an underlying condition such as diabetes, rheumatoid arthritis, steroid treatment, granulomatous lobular mastitis and trauma.
Management begins with first making the correct diagnosis. When there is no evidence of an abscess, appropriate antibiotics for mastitis are started early to prevent or reduce formation of an abscess. If the infection does not settle rapidly with one course of antibiotic treatment, hospital referral is indicated.
When an abscess is suspected, identification of the potential cause will aid optimum treatment. Symptoms, especially pain and fever, should be managed and immediate aspiration or drainage of abscess undertaken. Ultrasound guided aspiration may be required. Failure to recognise the need for drainage may lead to complications and litigation.
1) Antibiotic treatment
The antibiotic of choice for treating most breast infections is flucloxacillin or co-amoxyclav. Flucloxacillin is more appropriate in lactational infections; co-amoxyclav is better in non lactational. Where there is penicillin allergy, erythromycin or clarithromycin may be used — a combination of erythromycin and metronidazole is recommended in non-lactational and skin-associated infections. It may be necessary to change the antibiotics according to microbiological sensitivity of the causative organisms.
Care must be taken not to give certain antibiotics to breastfeeding mothers such as ciprofloxacin, chloramphenicol and tetracycline as these may enter the breast milk.
2) Needle aspiration
Percutaneous aspiration of breast abscess is minimally invasive and has a high success rate. This may be done in the GP surgery, emergency department or OPD and most patients do not require hospital admission. It is effective especially in small abscesses.
Repeated attendance and aspirations in OPD may be necessary to achieve cure. Ultrasound scan (USS) is sometimes used to guide the needle, especially in deep-seated abscesses. USS is very useful in accurately demonstrating the presence or absence of a fluid collection in the acutely inflamed breast.
Where resources exist, all patients should have serial percutaneous needle aspirations under USS guidance. This is the best method to drain breast abscesses. A wide bore needle such as 14-gauge or 16-gauge is preferred for aspiration.
Most patients may require local anaesthesia (LA). One per cent lignocaine with 1:200,000 adrenaline is used. The LA is infiltrated through the skin. The abscess is then aspirated with a wide bore needle. All aspirates should be sent for microscopy culture and sensitivity. The abscess cavity may be irrigated with LA and up to 50ml of 1 per cent lignocaine with 1:200,000 adrenaline can be used. This helps dilute thick pus, which reduces pain, bleeding and bruising. In large cavities, more than 50ml LA may safely be used provided this is all aspirated later.
Patients should be reviewed every two to three days with or without USS and aspiration repeated until there is no further fluid visible in the abscess cavity or no further pus aspirated. This should be combined with appropriate antibiotic cover.
3) Incision and drainage
Large incisions are not necessary for drainage. Obvious abscesses with very thin overlying skin require a small stab incision only. The abscess may be irrigated with LA and adrenaline solution. This may be repeated every two to three days in the breast clinic. Incised breast abscesses do not require drains or packs. Almost all patients requiring open incision and drainage for breast abscess can have it done under LA.
Even patients with necrotic skin overlying the abscess can have the skin excised under LA and the abscess drained as above.
Patients with abscesses developing from non-lactating infections are managed in a similar fashion.
4) Definitive surgery
This is required in patients with recurrent abscesses. It is more common in non-lactating abscesses, especially in patients with periductal mastitis with recurrence and/or development of mammary duct fistula.
Excision of the diseased ducts is indicated in these cases and sometimes a complete total duct excision is required to significantly reduce the chance of recurrence. Where a fistula is present, excision of the fistula combined with total duct excision is usually effective. Very rarely, the nipple needs to be excised as part of the surgery.
All patients with breast abscess must be offered an ultrasound and, if above 35 years, a bilateral mammogram when the infection has resolved. Smokers should be advised of the association with recurrent breast infection and abscesses.
Breast infection must be recognised early and prompt treatment with appropriate antibiotics started to prevent progression to an abscess.
Current treatment is by repeated percutaneous aspirations under radiological control and appropriate antibiotic therapy. When ultrasound scan is not readily available, abscesses must be aspirated without preliminary ultrasound. In recent times, surgical incision and drainage is rarely required and when indicated mini stab incision and drainage is sufficient.
It is safe practice to offer all patients mammogram and/or ultrasound scan when their infections have resolved to rule out an underlying breast cancer.