Please tell me the pathophysiology of breast abcess?

Walled-off infection: An abscess anywhere is a local bacterial infection that has successfully isolated itself from the immune system by forming a pocket of pus with no blood flow or viable tissue inside. Because there is no blood flow, antibiotics will never reach an abscess and are ineffective, so the only treatment is drainage. Sometimes they rupture and drain on their own, but sometimes an incision is needed.