Extraskeletal osteosarcoma arising in the globe of an irradiated, heritable retinoblastoma survivor.

Purpose: Individuals with hereditary retinoblastoma (RB) carry a heightened risk of developing subsequent malignant neoplasms that is amplified by prior radiation treatment. Here, we present a novel case of intraocular extraskeletal osteosarcoma (ESOS) arising in the phthisical eye of an irradiated, heritable RB survivor. Observations: A 23-year-old man with a history of bilateral RB presented with a year of left orbital and eye pain. On examination, the left eye had mucopurulent discharge and exposed orbital tissue. On imaging, the left globe, periocular structures, optic nerve, and optic nerve sheath were surrounded by abnormal contrast enhancement. As a result, the left eye was enucleated. On histopathology, an ESOS filled most of the globe with extraocular extension. The tumor was associated with focal, benign-appearing intraocular bone of the type commonly seen in phthisical eyes. The patient was found to have pulmonary metastases, consistent with metastatic stage IV osteosarcoma. He was started on systemic chemotherapy and underwent an exenteration of the left orbit. Conclusions and importance: This case highlights a rare manifestation of osteosarcoma in an irradiated, heritable RB survivor. It underscores the need for longitudinal ophthalmic examination that potentially includes periodic echography when eyes are phthisical, and oncologic surveillance in RB survivors to facilitate early diagnosis and intervention for life-threatening secondary malignancies. The findings also suggest that osteosarcoma can arise from metaplastic bone within phthisical globes.