Fat necrosis is typically caused by trauma to the breast. The damaged, necrotic fat is phagocytosed by macrophages, which become lipid-laden. The lesion resolves as a collagenous scar within weeks to months. The firm scar can mammographically and grossly resemble a carcinoma. An abscess may form a palpable but painful mass lesion, and often from Staphylococcus aureus infection when localized. A fibroadenoma is a neoplasm, and tumors are not induced by trauma. Inflammatory carcinoma refers to dermal lymphatic invasion by an underlying breast carcinoma, giving a rough red-to-orange appearance to the skin. Sclerosing adenosis is a feature of fibrocystic changes, a common cause of nontraumatic breast lumps.