Acute mastitis, microscopic
While breastfeeding an infant, usually in the first month, the skin of the breast may become irritated, tender, and inflamed. This skin may fissure, predisposing to infection with entry of microorganisms into underlying breast tissue. Acute mastitis typically involves just one breast and is most often caused by bacterial organisms such as Staphylococcus aureus, although streptococci can produce this condition, with neutrophilic infiltrates (▼) seen here microscopically in an acinus. If untreated by antibiotic therapy, spread of infection, abscess formation, and reduction in lactation can occur.