Patient Story
A 23-year-old woman, who is currently breastfeeding and 6 weeks postpartum, presents with a hard, red, tender, indurated area medial to her right nipple (Figure 92-1). She also has a low-grade fever. Because there is a local area of fluctuance, incision and drainage is recommended. The area is anesthetized with 1% lidocaine and epinephrine and drained with a #11 scalpel. A lot of purulence is expressed and the wound is packed. The patient is started on cephalexin 500 mg qid for 10 days to treat the surrounding cellulitis and seen in follow-up the next day. The patient was already feeling better the next day and went on to full resolution in the following weeks.
Introduction
Mastitis, defined as an infection of the breast, and breast abscesses are typically found in breastfeeding women (Figure 92-1). A breast abscess and mastitis unrelated to pregnancy and breastfeeding can occur in older women (Figure 92-2).
Figure 92-2
Breast abscess and cellulitis in a 40-year-old woman. Pus was already draining at the time of presentation, but a further incision and drainage through the openings yielded another 30 cc of pus. The patient was treated with oral antibiotics and scheduled to get a mammogram when the infection is cleared. (Courtesy of Richard P. Usatine, MD.)
Epidemiology
Etiology and Pathophysiology
- Mastitis is most commonly caused by Staphylococcus aureus, Streptococcus species, and Escherichia coli.
- Recurrent mastitis can result from poor selection or incomplete use of antibiotic therapy, or failure to resolve underlying lactation management problems. Mastitis that repeatedly recurs in the same location, or does not respond to appropriate therapy, may indicate the presence of breast cancer.3
Risk Factors
- Risk factors for mastitis include a history of mastitis with a previous child, cracks and nipple sores, use of an antifungal nipple cream in the same month, and use of a manual breast pump.4
- Risk factors for breast abscess include maternal age older than 30 years, primiparity, gestational age of 41 weeks, and mastitis.2,3 Breast abscess develops in 5% to 11% of women with mastitis, often caused by inadequate therapy.3
Diagnosis
- Mastitis causes a hard, red, tender, swollen area on the breast (Figures 92-1, 92-2, and 92-3). Erythema is less visible in darker skin but the swelling is still prominent (Figure 92-3).
- Usually unilateral, so the breast size difference can be obvious (Figure 92-3).
- Fever is common.
- Pain usually extends beyond the indurated area.
- It is often associated with other systemic complaints, including myalgia, chills, malaise, and flu-like symptoms.
- Breast abscess can occur with mastitis, except a fluctuant mass is palpable. (In Figure 92-2, the fluctuant mass is close to the midline with two openings of spontaneous drainage. The remainder of the erythema is the mastitis.)