This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology and breast, Subject name: Surgery
T-4d in TNM staging of breast cancer is 
Select and explain. 
A. Involvement of skin, B. Involvement of chest wall, C. Inflammatory carcinoma, D. Peau'de orange appearance
C: Inflammatory carcinoma
Answer: C: Inflammatory carcinoma 
Explanation: OT4a: Extension to the chest wall, not including pectoralis muscleOT4b: Edema (including peau d'orange) or ulceration of the skin, or satellite skin nodules confined to the same breastOT4c: Both T4a and T4bT4d: Inflammatory carcinoma