Cavitary changes in retinoblastoma: relationship to chemoresistance.

OBJECTIVE: To describe the clinical features and outcome of treatment of retinoblastomas presenting with ophthalmoscopically visible cavities.
DESIGN: Retrospective, noncomparative, interventional case series. PARTICIPANTS: Sixteen eyes of 15 patients harboring retinoblastomas with ophthalmoscopically visible cavities treated between February 1995 and July 2003.
METHODS: Patient demographics, eye and tumor characteristics, and response to treatment were recorded. MAIN OUTCOME MEASURES: Decrease in tumor size and tumor recurrence.
RESULTS: The mean patient age at diagnosis was 20 months. The mean number of retinoblastomas per eye was 2 (range, 1-6). Associated subretinal fluid was graded as absent in 5 eyes, minimal in 6 eyes, mild in 4 eyes, and severe in 1 eye. None of the tumors had vitreous seeds, and 5 (31%) had subretinal seeds. Ophthalmoscopically visible calcification occupied a mean of only 3% of the tumor (median, 0%; range, 0%-30%). Intratumoral cavities were characteristically visible in the superficial portion of the tumor and had a mean diameter of 2.0 mm (median, 1.5; range, 0.5-5.0). The mean number of cavities per tumor was 2 (median, 1; range, 1-5). Three tumors were treated with enucleation, 1 with observation, and 12 with chemoreduction. Two months after chemoreduction, the mean reduction in tumor base was 19% (median, 16%; range, 0%-42%), and the mean reduction in tumor thickness was 18% (median, 12%; range, 0%-59%). During a mean follow-up of 32 months (median, 23; range, 12-58), none of the cavitary retinoblastomas recurred or gave rise to vitreous or new subretinal seeds.
CONCLUSION: Retinoblastomas containing ophthalmoscopically visible cavitary spaces do not show a substantial decrease in size after chemotherapy. Cavitary changes in retinoblastoma may be a sign that the tumor is well differentiated and may impart a better prognosis.