This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Ophthalmology
Second most common malignancy in a patient with retinoblastoma is: 
Select and explain. 
A. Nephroblastoma, B. Osteosarcoma, C. Neuroblastoma, D. Craniopharyngioma
B: Osteosarcoma
Answer: B: Osteosarcoma 
Explanation: Retinoblastoma: It is the most common primary intraocular malignancy of childhood. The mutation occurs in the retinoblastoma gene (Rb) at chromosome 13q14. This is a tumor suppressor gene. One mutated copy may be inherited in an autosomal dominant fashion (germline mutation). If a second mutation spontaneously occurs in any cell, tumorigenesis is likely. Individuals with a germinal mutation are at risk for the development of tumors other than retinoblastoma (pineal tumors, osteosarcoma, and other soft tissue sarcomas). Ref: Braverman R.S. (2012). Chapter 16. Eye. In W.W. Hay, Jr., M.J. Levin, R.R. Deterding, J.J. Ross, J.M. Sondheimer (Eds), CURRENT Diagnosis & Treatment: Pediatrics, 21e.