This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Vascular surgery, Subject name: Surgery
The most common site of lymphangiosarcoma: 
Select and explain. 
A. Liver, B. Spleen, C. Post-mastectomy edema of arm, D. Retroperitoneum
C: Post-mastectomy edema of arm
Answer: C: Post-mastectomy edema of arm 
Explanation: Angiosarcoma: Rare tumour that develops as a complication of long-standing (>10 years) lymphoedema. Stewa and Treves described lymphangiosarcoma of the upper extremity in women with ipsilateral lymphedema after radical mastectomy. (Stewa-Teres syndrome) Clinical Features: Acute worsening of edema. Appearances of sub-cutaneous nodules with propensity towards hemorrhage and ulceration. Treatment: Pre-operative chemotherapy and radiotherapy followed by surgical excision (radical amputation) Associated with poor prognosis. Ref: Sabsiton 20th edition Pgno: 766