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.
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What this article covers
- Overview
Mastitis is inflammation of the breast parenchyma and periglandular connective tissue, most commonly an infective process in a breastfeeding woman.
- Epidemiology
Typical patient: A breastfeeding woman, most often primiparous, with unilateral breast symptoms beginning 2 to 4 weeks postpartum, though onset can occur at any point during lactation.
- Risk factors
Nipple trauma or cracking: The portal of entry for skin flora into the ductal system; poor latch and improper infant positioning are the usual precipitants.
- Pathophysiology
Milk stasis is the initiating event: an incompletely drained duct lets retained milk provoke a local inflammatory reaction, and the resulting edema narrows the duct further, worsening the obstruction.
- Clinical features
Localized pain and tenderness: A wedge-shaped, unilateral area of breast tenderness is the presenting complaint in most patients.
- Differential diagnosis
Breast engorgement: Bilateral firmness and fullness from milk production exceeding removal, but no fever and no focal erythema, improving with frequent feeding rather than antibiotics.
- Diagnosis
What establishes the diagnosis: Mastitis is a clinical diagnosis, made by unilateral breast pain with erythema, edema, and warmth in a breastfeeding patient, distinguished from simple engorgement by…
- Management
First, continue milk removal from the affected breast: keep breastfeeding on that side, or use a breast pump if breastfeeding is not possible, since evacuating the stagnant milk is central to…
- Complications
Breast abscess: Develops in a minority of untreated or inadequately treated cases and needs ultrasound-guided aspiration or incision and drainage once it forms.
- Prognosis
Uncomplicated mastitis: Most patients improve within 48 to 72 hours of starting an appropriate oral antibiotic combined with continued milk removal.
- Prevention
Correct latch and positioning: Early lactation support reduces nipple trauma, the portal of entry for infection.
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Related articles
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.