An abscess is an accumulation of pus in breast tissue, which develops as a defensive reaction, usually against infection, but also due to the presence of foreign objects. An abscess can occur anywhere in the body. Most breast abscesses develop in association with lactation and breast feeding (mastitis ), but not all. Breast abscesses occuring in non-lactating and postmenopausal women are a bit more unusual and would be suspicious, at least initially, for malignant breast cancer. Because of this, a thorough evaluation ,including a fluid aspiration,is warranted. An abscess is ussually discovered clinically or by a woman herself as a 'lump', but it may also be revealed on a mammogram. A woman who has already undergone breast cancer treatments or biopsies may also develop an abscess in the following days or weeks. Abscesses are often accompanied by pain, fever, and breast tenderness. However, not all abscesses are accompanied by obvious signs of inflammation, so diagnosing them is not always a simple matter.
Release of cytokines can start an inflammatory response within the breast
When foreign organisms (bacteria) enter a wound, they can kill many of the local cells. These dying cells release cytokines ( cytokines are small proteins that are secreted by certain cells which signal an immune system response). The release of cytokines starts an inflammatory reponse, increasing blood flow and bringing large numbers of white blood cells to the region. As part of this immune system response, a fibrous 'wall' or 'capsule' is formed by the healthy cells next to the area. Pus accumulates within this capsule, often forming a palpable bulge, or a 'cavity' within the breast. The image below shows the fibrous tissue of the encapsulating abscess wall, with a few inflammatory cells, and small amounts of pus.
Specific causes of breast abscesses, possibility of breast cancer.
Staphylococcus aureus bacteria (a 'staph' infection) is a common cause for breast abscesses, especially in lactating and pregnant women. An abscess can be thought of as a 'skin' complication really, and many abscesses are caused by bacteria commonly found on normal skin. A 'break' or tear in the skin allows bacteria to enter beneath the skin, and pus and inflammation accumulate. Some breast abscesses are also caused by tuberculosis (normally a lung condition). In poorer parts of the world, up to 4% of all benign breast lumps examined are actually abscesses associated with tuberculosis. However, a breast abscess caused by TB would be considered extremely rare in non-third-world countries.
breast abscesses can be brought on by a variety of causes
There is speculation that steroid treatments, trauma, and even smoking can help bring about an abscess. Breast abscesses have also been associated with diseases like diabetes, rheumatoid arthritis, and there is always the rare possibiliy that breast carcinoma or inflammatory carcinoma can be an underlying cause. Essentially, the development of an abscess in the absence of a clear 'open wound' or opportunity indicates that something is causing the cells and tissues associated with immune responses in the area to be compromised. Or, it might mean that neoplastic cell growth or tissue destruction in tissues such as the breast ducts has caused a build up of fluids (secretions), and these stagnant fluids are prone to infection. In that instance, the presence of an absense could be a byproduct of gland and tissue changes caused by a developing breast cancer. However, the vast majority of potential underlying causes turn out to be benign.
Treatment of a breast abscess
Breast abscesses are usually drained, either by surgical incision (sometimes called 'lancing') for large, progressive abscesses or by needle aspriation. Usually an abscess is not drained until the lesion transforms from a 'harder' serous inflammation to 'softer' pus stage. Some breast abscesses will require multiple needle aspirations, but most show improvement and resolution with a single treatment. About 90% of breast abscesses can be managed by repeated needle aspirations rather than formal surgery. Many patients are also treated with antibiotics, depending on the individual and the type of bacteria found.
inflammatory breast lesions are more suspicious for malignancy
Any inflammatory breast lesion in a postmenopausal women would carry some suspicions of malignancy, so after the abscess has been drained an excisional biopsy is usually undertaken. If an inflammatory mass ( revealed by ultrasound) does not seem to tranfrom into pus (a thick, sticky pale yellow or yellow-green fluid) and does not seem to respond to antibiotics,(and get smaller or resolve), then the possibility of underlying breast carcinoma would have to be seriously considered.
Subareolar and peripheral breast abscesses
In non-lactating women, breast abscesses tend to develop either below the nipple (subareolar) or around the breast periphery. (Lactation-related abscesses tend to develop in and around the breast ducts). Subareolar breast abscesses are a bit more troublesome in terms of management, because they tend to last longer and tend to recur. Even though it is a rare condition, it tends to affect young women the most. Cosmetically, it can also cause deformation of the nipple and areola. Sub and periareolar (around the nipple) abscesses also frequently cause nipple discharges. Subareolar abscesses might even require a more extensive surgical intervention, including the removal of any damaged ducts,(depending on the situation and underylying cause) and reconstruction of the nipple.
Imaging studies for breast abscesses
Even though imaging studies are frequently undertaken to rule out malignancy, mammograms and ultrasounds of breast abscesses are not always conclusive. A breast abscess will likely appear on a mammogram as an ill-defined mass, typically with some areas of increased density and distortion. These types of features cannot be confidently differentiated from breast cancer lesions. Mammography is also less sensitive for the diagnosis of younger women and those with dense breast tissue.
Ultrasound can help distinguish between an abscess and breast cancer
Ultrasound tends to be useful in ruling out malignancy, though depending on the location of the abscess, the sonograph image may not always make the picture any clearer. A breast abscess will usually show on ultrasound as an ill-defined echogenic mass with central irregular hypoechogenecity or septations. There may or may not be posterior acoustic enhancement. Breast carcinoma on the other hand tends to show an as irregular hypoechoic mass, which may or may not have posterior acoustic shadowing. However, when the abscess is located right under the nipple and without a palpable mass, the abscess might not even show up on ultrasound at all. This might be a situation where MRI is used as it tends to provide a more comprehensive view of the lesion, even below the nipple.
The goal is to avoid surgery if possible
Obviously, the goal of imaging studies surrounding abscesses is to rule out carcinoma and avoid unneccesary major surgeries.carcinoma at mammography. Singapore Med J 2007; 48(10). 958