Microscopic scleral invasion in retinoblastoma: clinicopathological features and outcome.

Objective: To describe the clinical and pathological features of patients with retinoblastoma and microscopic scleral invasion.

Methods: We reviewed all pathology slides of patients with microscopic scleral invasion who were included in 3 prospective treatment protocols (1988-2007). All patients received adjuvant chemotherapy (moderately intensive chemotherapy in the first 2 protocols or a more intensive combination in the third one). Only patients with cut-end invasion received orbital radiotherapy.

Results: Thirty-two of 386 patients had enucleated eyes with intrascleral (21 cases) and transscleral (11 cases) invasion. Of these cases, 20 had tumor invading the optic nerve beyond the lamina cribrosa, with 6 of these having tumor at the surgical margin. Sixteen were treated with moderately intensive chemotherapy and 16 received a higher-intensity regimen. Five-year overall survival was 0.77. Seven patients had an extraocular relapse (central nervous system metastasis, n = 4; systemic metastasis, n = 2; and involving the orbit, n = 3, isolated in 1 and combined with central nervous system disease in 2). All patients who had a relapse died. Patients receiving the intensive regimen had a significantly better outcome (P = .007).

Conclusions: Microscopic scleral invasion might be a risk factor for extraocular relapse, and more intensive chemotherapy results in improved survival for these patients.