Adenocarcinoma of the Retinal Pigment Epithelium Arising in Conjunction with Late Recurrence and Systemic Metastasis of Retinoblastoma

In 1974, an 8-month-old male was diagnosed with bilateral retinoblastoma. His left eye was enucleated, while the right eye was salvaged with a combination of external beam radiotherapy (4,000 cGy total, divided in 20 fractions) and retinal laser treatment. Thirty-nine years later, he developed intraocular recurrence of retinoblastoma with extrascleral spread. Histopathological examination also identified a second distinct malignancy, retinal pigment epithelium adenocarcinoma, arising in continuity with the retinoblastoma. Further investigation revealed foci of metastatic retinoblastoma in his parotid gland. He was subsequently treated with a combination of orbital exenteration, extensive neck dissection, and resection of metastatic foci, followed by a high-dose ablative chemotherapeutic regimen consisting of cisplatin, vincristine, and cyclophosphamide. Although very rare, late recurrence of retinoblastoma with systemic metastasis is possible, and continued clinical observation and appropriate long-term follow-up should be considered. Additionally, it is important to consider a second primary intraocular tumor in the differential diagnosis, especially in a patient with heritable retinoblastoma who has undergone radiation therapy.