Breast Abscess

Etiology

Lactational breast abscesses are most often caused by Staphylococcus aureus and Streptococcal species. Methicillin-resistant S. aureus is becoming increasingly common. Typically, non-lactational breast abscesses are a result of a mixed flora with S. aureus, Streptococcus, and anaerobic bacteria.[4][5]

Epidemiology

Lactation is the most common association with breast infections, present in 10% to 33% of these women. Lactational mastitis is present in 2% to 3% of lactating women, and 5% to 11% of these patients may develop an abscess. This is most common in women of childbearing age, with a mean age of 32 years. Nonlactating breast abscesses have a wider age range, with a peak incidence in the fourth decade of life. There is a strong association between diabetes and smoking with non-lactational breast abscesses. Obese patients and African Americans have a greater incidence of breast abscess. Nipple piercings have also been associated with subareolar breast abscesses in the nonlactating population.[6]

Pathophysiology

To understand the pathophysiology of breast abscesses, you must understand the anatomy of the breast. The breast contains breast lobules, each of which drains to a lactiferous duct, which in turn empties to the surface of the nipple. There are lactiferous sinuses which are reservoirs for milk during lactation. The lactiferous ducts undergo epidermalization where keratin production may cause the duct to become obstructed, and in turn, can result in abscess formation. Abscesses associated with lactation usually begin with abrasion or tissue at the nipple, providing an entry point for bacteria. The infection often presents in the second postpartum week and is often precipitated in the presence of milk stasis. The most common organism known to cause a breast abscess is S. aureus, but in some cases, Streptococci, and Staphylococcus epidermidis may also be involved. Women are encouraged to continue breastfeeding or using a breast pump to continue draining milk from the affected ducts.[7]

History and Physical

The patient will usually provide a history of breast pain, erythema, warmth, and possibly edema. Patients may provide lactation history. It is important to ask about any history of prior breast infections and the previous treatment. Patients may also complain of fever, nausea, vomiting, purulent drainage from the nipple, or the site of erythema. It is also important to ask about the patient's medical history, including diabetes. The majority of postpartum mastitis are seen within 6 weeks of while breast-feeding

The patient will have erythema, induration, warmth, and tenderness to palpation at the site in question on the exam. It may feel like there is a palpable mass or area of fluctuance. There may be purulent discharge at the nipple or site of fluctuance. The patient may also have reactive axillary adenopathy. The patient may have a fever or tachycardia on the exam, although these are less common.

Evaluation

The cornerstone of diagnosis of a breast abscess is the physical exam. A complete blood count may be obtained to evaluate for leukocytosis, but it is not necessary. If there is any frank drainage, cultures can be obtained to help guide antibiotic treatment. A breast ultrasound may be obtained if there is a question of cellulitis versus abscess, to evaluate for a drainable fluid collection. On ultrasound, abscesses may appear as ill-defined masses with internal septations.

In some cases, to confirm the presence of a  breast abscess, needle aspiration is done and the fluid analyzed.

Treatment / Management

Incision and drainage are the standard of care for breast abscesses. If the patient is seen in a primary care setting by a provider that is not comfortable in performing these procedures, the patient may be started on antibiotics and referred to a general surgeon for definitive treatment. Needle aspiration may be attempted for abscesses smaller than 3 cm or in lactational abscesses. Non-lactational abscesses have a higher rate of recurrence and often require multiple drainage procedures. Incision and drainage have lower recurrence rates, but they are more invasive than needle aspiration and may lead to scarring and possible poor cosmesis. If there is a recurrence of an abscess after needle aspiration, incision and drainage should be performed. If there is a large cavity, follow incision and drainage, packing of the cavity may be done to promote further drainage and prevent the skin incision from healing before drainage is complete. Typically, these wounds heal fairly quickly. If the cause of the abscess is an obstructed or ectatic lactiferous duct, surgical excision may be necessary.[2][8]

A course of antibiotics may be given before or following drainage of breast abscesses. There are many options for treatment, and consideration must be given to the possible pathogens involved based on the patient's history. It is also important to consider if the patient is breastfeeding and whether the antibiotics given are safe in breastfeeding patients. Cultures should be obtained to guide antibiotic therapy, especially in recurrent breast abscesses. Some of the antibiotics to be considered are nafcillin, Augmentin, doxycycline, Trimethoprim, clindamycin, or vancomycin. Antibiotics may be required for 4-7 days.

Patients with large breast abscesses or signs of sepsis should be considered for admission to the hospital. Large breast abscesses may need incision and drainage in the operating room, packing of the wound for healing by secondary intention, and possibly intravenous antibiotics.

Pain control with NSAIDs and/or prescription narcotics should also be considered.

If a breast abscess has been diagnosed, the infant should not be breastfed on that breast to prevent transmission of the infection.

Differential Diagnosis

• Benign or malignant breast mass
• Inflammatory breast cancer
• Cellulitis

Prognosis

The majority of isolated cases of breast abscess have good outcomes, but it can lead to pain, scarring, and a poor quality of life in women with recurrent infections.

Most patients have recovery within 2-3 weeks following mastitis. Any patient that continues to have features of mastitis after 5 weeks should be evaluated for malignancy or infection.

The majority of breast abscess tend to occur in the postpartum period, and if it is seen in a nonlactating female, the onus is on the clinician to rule out inflammatory breast cancer, new-onset diabetes, or infection with mycobacterium.

Complications

• Scarring
• Breast asymmetry
• Pain
• Fistula
• Retraction of nipple-areola complex leading to cosmetic deformity