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The parents of a 3-year-old girl who recently completed treatment for unilateral retinoblastoma are expecting a second child. They are concerned that this new child will also develop retinoblastoma. There is no other family history of cancer, and both parents are healthy. You counsel the parents that the risk this second child will develop retinoblastoma is which of the following?

A. < 5%

B. 25%

C. 50%

D. 75%

E. 90%

Answer: A

Genetic counseling for patients with retinoblastoma is based on the proband's presentation, family history and genetics. The 3-year-old girl described in the question stem likely had sporadic, non-hereditary retinoblastoma due to her unilateral disease and older age of presentation. With no family history of cancer, the risk for the sibling is 1% if the affected proband has unilateral retinoblastoma. The risk is 2% if the proband has bilateral disease. These risks remain for future siblings due to the possibility of gonadal mosaicism.

A 4-month-old boy is found to have bilateral leukocoria and strabismus at his well-child exam. He is diagnosed with bilateral retinoblastoma after an evaluation by a pediatric ophthalmologist and a brain magnetic resonance imaging (MRI) scan. Which of the following tumors is he also at risk for?

A. Neuroblastoma

B. Hepatoblastoma

C. Hodgkin lymphoma

D. Osteosarcoma

E. Wilms tumor

Answer: D

This young infant with bilateral retinoblastoma most likely has a germline alteration in one copy of the tumor suppressor gene RB1. Approximately 95% of children with bilateral retinoblastoma carry a germline mutation in the RB1 gene. Individuals with RB1 gene abnormalities are at increased risk for developing secondary cancers, particularly sarcomas, such as osteosarcoma, and melanomas. Neuroblastoma, hepatoblastoma, Hodgkin lymphoma, and Wilms tumor have not been specifically identified as RB1-dependent tumors.

Exam of a term newborn male reveals absence of irises and mild hypospadias. The patient's siblings and parents are healthy with no known medical conditions. Which tumor is the patient at most risk of developing?

A. Medulloblastoma

B. Wilms ...

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