This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Breast Cancer - Types and Staging, Subject name: Surgery
All of the following are true regarding cystosarcoma phyllodes except 
Select and explain. 
A. Cut surface appears like leaf, B. Mastectomy preferred for malignant tumors, C. Arise from a single epithelial cell type, D. Excision biopsy for diagnosis in benign tumors.
C: Arise from a single epithelial cell type
Answer: C: Arise from a single epithelial cell type 
Explanation: Ans) c (Arise from ) Ref Sabiston 18th ed pg 871Phyllodes tumor contain a biphasic proliferation of stromal & mammary epithelium.They are finn lobulated masses. Histologically whorled stroma forms larger cleft lined by epithelium that resembles clusters of leaf like structure.Mammographically rounded densities with smooth borders indistinguishable from fibroadenomas.USG may reveal a discrete structure with cystic spaces.Core biopsy gives correct diagnosis in only 50% case.So, excision biopsy is the best.Local excision of phylloids tumor is curative in benign tumors.For border line phyllodes tumor excision with 1 cm margin.For malignant phyllodes tumor- total mastectomy.