This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: miscellaneous, Subject name: Anatomy
Most common second malignancy in patients with femoral retinoblastoma is 
Select and explain. 
A. Teratoma, B. Medullary carcinomas, C. Osteosarcoma, D. Malignant melanoma
C: Osteosarcoma
Answer: C: Osteosarcoma 
Explanation: Patients with family retinoblastoma are at greatly increased risk of developing Osteosarcoma and and some other soft tissue sarcoma.. Alteration in RB pathway, involving INK proteins, cyclin D dependent kinases, and RB family proteins which are present in normal cells lead on to tumor suppressor gene. And associated somatic tissue mutation cause increased risk of other tumors. Refer robbins 9/e 299