Osteogenic sarcoma of the humerus after cobalt plaque treatment for retinoblastoma

A 13-year-old boy developed an osteogenic sarcoma of the right humerus ten years after treatment for bilateral retinoblastoma. The bilateral retinoblastoma has been managed with enucleation of one eye and successful treatment of the solitary tumor in the other eye with a single application of a local 10-mm round cobalt plaque. Patients with bilateral retinoblastoma have a significant (15 to 20%) chance of developing a second, nonocular, neoplasm. These neoplasms have occurred from one to 42 years after the treatment for retinoblastoma. The most common of these tumors is an osteogenic sarcoma; it may occur after external beam irradiation, local cobalt plaque, or no irradiation. The tumors may be in the skull or at distant sites whether or not these patients receive radiation.