Snapshot A 29-year-old, G1P1, woman presents with a painful and erythematous right breast. Since the birth of her first son 3 weeks ago, she has been exclusively breastfeeding. Upon physical exam, there are visible small fissures around the nipple. The breast feels warm. Purulent discharge from the nipple is noted. Introduction Clinical definition inflammation of the breast often associated with milk stasis during lactation Epidemiology Incidence 3-20% of lactating women Demographics occurs in lactating women any inflammatory breast in a post-menopausal woman is cancer until proven otherwise often occurs within first 12 weeks post-partum Risk factors lactation injury to nipple poor attachment of infant to breast history of prior mastitis Etiology Pathophysiology pathophysiology milk stasis, or accumulation of milk, may cause inflammatory response milk stasis also creates favorable conditions for growth of bacteria infection often starts from nipple fissures often due to Staphylococcus aureus and Staphylococcus albus can also be due to yeast, especially if infant has oral candidiasis or diaper dermatitis Presentation Symptoms primary symptoms tender, hot, and swollen breast usually unilateral flu-like myalgia chills fever Physical exam inspection localized redness on the breast often wedge-shaped warmth and induration on the breast cracked nipples or visible fissure swollen lump may indicate breast abscess may have purulent nipple discharge suspect yeast mastitis if pain out of proportion to clinical findings shooting pain from nipple to chest wall Imaging Ultrasound indications if breast abscess is suspected findings fluid pocket seen inside breast Studies Labs may see elevated white blood cell count milk culture indications if no response to initial antibioitics if recurrent or chronic mastitis if there is presence of abscess Diagnostic criteria mastitis is typically diagnosed clinically based on physical exam Differential Engorgement pain relief and resolution of symptoms with emptying of milk, ice packs, and analgesics Fibroadenoma no signs of infection Treatment Conservative continue breastfeeding safe for infants contraindicated in women with human immunodeficiency virus (HIV) empty breasts of milk every 6 hours indication for mild symptoms lasting less than 1 day outcomes may shorten duration of mastitis may improve rates of normal lactation Medical dicloxacillin or cephalexin indications symptoms persist after 1 day of effective, regular milk removal milk culture indicates infection visible nipple fissure breast abscess clindamycin or trimethoprim-sulfamethoxazole indication if methicillin-resistant Staphylococcus aureus (MRSA) is suspected fluconazole indication if yeast mastitis is suspected outcomes successful if mother and infant are treated Operative surgical drainage indication breast abscess is diagnosed techniques first-line needle aspiration with or without ultrasound guidance otherwise incision and drainage for large abscesses Complications Breast abscess 3-12% of women with mastitis develop breast abscess treatment surgical drainage Vertical transmission of HIV infection from mother to infant 10-20x higher load of HIV RNA in milk during mastitis treatment cessation of breastfeeding Prognosis Prognostic variable favorable appropriate antibiotic treatment Survival with treatment very good