Most common inherited childhood tumor is:

Retinoblastoma is a neuroectodermal malignancy arising from embryonic retinal cells. It is the most common intraocular tumor in pediatric patients and causes 5% of cases of childhood blindness. Retinoblastoma is the prototype of hereditary cancers due to a mutation in the retinoblastoma gene (RB1), which is located on the long arm of chromosome 13 (13q14). Approximately 40% of retinoblastoma are inherited. Ref: Graham D.K., Quinones R.R., Keating A.K., Maloney K., Foreman N.K., Giller R.H., Greffe B.S. (2012). Chapter 31. Neoplastic Disease. In W.W. Hay, Jr., M.J. Levin, R.R. Deterding, J.J. Ross, J.M. Sondheimer (Eds), CURRENT Diagnosis & Treatment: Pediatrics, 21e.