This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Breast, Subject name: Pathology
A 30-year-old woman sustained a traumatic blow to her right breast. Initially, there was a 3-cm contusion beneath the skin that resolved within 3 weeks, but she then felt a firm, painless lump that persisted below the site of the bruise 1 month later. What is the most likely diagnosis for this lump? 
Select and explain. 
A. Abscess, B. Fat necrosis, C. Fibroadenoma, D. Inflammatory carcinoma
B: Fat necrosis
Answer: B: Fat necrosis 
Explanation: 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.