Breast Masses, Breast Complaints, and Diagnostic Breast Imaging in the Lactating Woman

Accessory breast tissue occurs in 2–6% of women, most commonly in the axilla, with bilaterality in about one-third of cases. Although this tissue is congenital, women may not notice its presence until they experience physiologic breast growth during pregnancy and lactation. (Level IV)

Plugged ducts occur in areas of milk stasis usually localized to a specific quadrant of the breast and resulting from milk that has remained unemptied. Plugs generally are self-limited and resolve with conservative measures such as increasing feeding frequency and gentle massage. (Level IV)

Galactocele, also known as a milk retention cyst, results from a persistent plugged duct. Galactocele is the most common benign breast mass in lactating women. (Level IV)

Phlegmon, a poorly defined fluid collection that results from obstruction and inflammation with or without infection, is well described in the surgical literature on perforated appendicitis and diverticulitis. A similar inflammatory phenomenon occurs in the lactating breast and may present as a tender mass in a ductal distribution, often associated with a recent or concurrent history of mastitis. It may have an irregular, heterogeneous, and vascular appearance on imaging and, therefore, may warrant biopsy to rule out malignancy. (Level IV)

Abscess is a well-defined fluid collection that progresses from unresolved mastitis in ~3% of cases. (Level II)

Lactating adenomas are painless benign masses that often present in the upper outer quadrant of breast tissue in pregnant and lactating patients, and likely are a result of hormonal stimulation. They can grow large quickly, and involute spontaneously with cessation of lactation. (Level IV)

Lactiferous sinuses may be more prominent in breastfeeding women and present as a subareolar mass. (Level IV)

Fibroadenoma is the most common benign breast mass to present in the reproductive years. ()

Phyllodes tumor, a fibroepithelial lesion similar to a fibroadenoma, has the potential for malignant transformation. Any suspicion of phyllodes requires surgical excision to rule out malignancy. (Level IV)

Cysts are particularly common in women with fibrocystic breasts and are readily classified as simple or complex by ultrasonography. Complex cysts require aspiration for cytologic analysis, whereas simple cysts can be observed. (Level IV)

Pseudoangiomatous stromal hyperplasia is a benign, often irregular, firm mobile mass that can grow large but does not require surgical excision if proven on biopsy. (Level IV)

Intramammary lymph nodes, although uncommon to palpate, are sometimes discovered by patients. Imaging can distinguish between benign versus malignant appearance. (Level I)

Fat necrosis is common after previous breast surgery or trauma; although benign, this condition may present as an irregular palpable mass that may be tender or asymptomatic. (Level IV)

Hematoma can also develop after trauma, such as a motor vehicle accident involving seat belt injury, or vigorous massage in the setting of lactation. In addition to a mass, transient nipple discharge may occur. (Level IV)

Periductal mastitis is an uncommon condition that generally presents in smokers and results from squamous metaplasia of the lactiferous ducts. Patients experience chronic, persistent abscesses, and fistulae in the superficial periareolar region. Optimal treatment is controversial and may include smoking cessation, antibiotic therapy, and/or drainage, with surgical excision reserved for refractory cases. (Level IV)

Idiopathic granulomatous mastitis is an inflammatory disorder of the breast with unclear etiology that results in erythema, abscess, and fistula formation. It most often occurs in young women of Hispanic descent within several years of pregnancy or lactation. (Level IV)

Breast cancer is the most commonly diagnosed malignancy among women in their reproductive years and thus may present during lactation. In addition, breastfeeding women are at risk for postpartum breast cancer, which has higher risk of metastatic spread than other forms of breast cancer. Women with postpartum breast cancer have markedly lower 5-year overall survival when compared with nulliparous cases, even adjusting for biologic subtype and stage at diagnosis. (Level III)