Breast abscess
A breast abscess is a localized, walled-off pus collection within breast parenchyma, most often complicating unresolved lactational mastitis from Staphylococcus aureus entering through a cracked nipple. Diagnosis is clinical, confirmed by ultrasound when fluctuance is uncertain, and first-line treatment pairs an oral antistaphylococcal antibiotic such as dicloxacillin with drainage, needle aspiration for a small collection or incision and drainage for a larger one, plus continued milk removal.
- Topic reviewThe full article, organized the way the exam asks it.
- ABIM-format MCQsVignettes with an explanation for every wrong answer.
- Key factsThe numbers and thresholds worth memorizing, up front.
- AI tutorMedBrain answers the question you're stuck on.
What this article covers
- Overview
A breast abscess is a localized, walled-off collection of pus within breast parenchyma, most often complicating lactational mastitis when periglandular cellulitis is not cleared by antibiotics and milk stasis persists.
- Epidemiology
Breast abscess is overwhelmingly a disease of breastfeeding women, complicating lactational mastitis that typically begins 2 to 4 weeks postpartum; it is more likely when mastitis is treated late…
- Risk factors
Nipple trauma: cracked, fissured, or bleeding nipples from a poor latch or infant positioning give Staphylococcus aureus direct access to the duct system.
- Pathophysiology
Staphylococcus aureus, including methicillin-resistant Staphylococcus aureus (MRSA), is the dominant pathogen; it reaches the ductal system through a fissure created by suckling trauma and…
- Clinical features
Timing: lactational abscess most often develops 2 to 4 weeks postpartum, usually complicating unresolved mastitis rather than a first presentation.
- Differential diagnosis
Lactational mastitis without abscess: the same tenderness, erythema, and fever, but no discrete fluctuant mass; resolves with oral antibiotics and milk removal alone.
- Diagnosis
What establishes the diagnosis: breast abscess is diagnosed clinically when a tender, erythematous breast harbors a discrete fluctuant mass, confirmed by ultrasonography showing a hypoechoic or…
- Management
First action: start empiric oral antistaphylococcal antibiotics and continue frequent, effective milk removal from the affected breast, either by continued direct breastfeeding or with a breast pump…
- Complications
Recurrence or reaccumulation: occurs when loculations are missed or drainage is incomplete, most often within days.
- Prognosis
Most breast abscesses resolve fully within 1 to 2 weeks of combined antibiotics and drainage, with an excellent prognosis and low mortality when treated promptly.
- Prevention
Correct latch and positioning: reduces nipple trauma, the main portal of entry.
Read the whole article
Subscribing to Internal Medicine opens every article, the full question bank and MedBrain, on the web, iPhone and Android.
Related articles
- Mastitis
Mastitis is inflammation of the breast parenchyma, most often infective and lactational, caused by milk stasis behind a blocked duct with secondary invasion by Staphylococcus aureus through a cracked nipple. Diagnosis is clinical; first-line treatment is continued milk removal plus an oral antibiotic such as dicloxacillin, with ultrasonography reserved for suspected abscess.
- Benign breast disease
Benign breast disease covers the nonmalignant conditions, fibrocystic change, fibroadenoma, phyllodes tumor, intraductal papilloma, and fat necrosis, that present as a breast mass, cyclical pain, or nipple discharge. Age-based imaging and, when indicated, core needle biopsy establish the diagnosis; most lesions are observed, while a fibroadenoma over 3 cm, a phyllodes tumor, or a papilloma is treated with surgical excision.
- Evaluation of a breast mass
Evaluation of a palpable breast mass follows an age-stratified imaging algorithm rather than a single test: women under 30 start with ultrasound, women 30 and older get mammography plus ultrasound, and the resulting BI-RADS category channels management toward observation, antibiotic therapy for mastitis, or core needle biopsy and surgical excision.
- Cutaneous abscess and furuncle
A cutaneous abscess is a collection of pus in the dermis or subcutaneous tissue, and a furuncle (boil) is a perifollicular abscess most often caused by Staphylococcus aureus that can coalesce with adjacent furuncles into a carbuncle. Diagnosis is clinical from a tender, fluctuant nodule, and the essential first treatment for any fluctuant collection is incision and drainage, with oral antibiotics reserved for systemic signs, extensive surrounding cellulitis, immunocompromise, or an inadequate response to drainage alone.
- Cellulitis
Cellulitis is a nonpurulent, spreading infection of the deep dermis and subcutaneous fat, usually caused by beta-hemolytic streptococci, diagnosed clinically and treated with antibiotics alone since there is no collection to drain.
- Breastfeeding
Breastfeeding is driven by prolactin-mediated milk production and oxytocin-mediated let-down, and its clinically important complication is lactational mastitis, treated with dicloxacillin or cephalexin 500 mg PO four times daily for 10 to 14 days while breastfeeding continues, alongside engorgement, nipple injury, plugged ducts, and galactocele.
- Inflammatory breast cancer
Inflammatory breast cancer is a clinically diagnosed, rapidly progressive form of locally advanced breast cancer causing diffuse erythema, edema, and peau d'orange from dermal lymphatic tumor emboli, often mistaken for mastitis. It is at least T4d (stage IIIB) at diagnosis and requires neoadjuvant chemotherapy followed by modified radical mastectomy and postmastectomy radiation; breast-conserving surgery is contraindicated.