Intravitreal topotecan injection-induced conjunctival fibrosis mimicking extraocular extension of retinoblastoma: a rare complication

A 3-year-old girl treated with intravenous chemotherapy for bilateral retinoblastoma (RB) and a standard technique of intravitreal topotecan for vitreous seeds in the left eye developed a conjunctival nodule at the injection site. Ultrasound biomicroscopy showed normal underlying sclera and ciliary body. Fundus examination of the left eye showed partly calcified vitreous seeds. Suspecting extraocular RB extension, we performed extended enucleation. Histopathology revealed partially regressed intraocular RB, and the conjunctival nodule showed subepithelial cystic degeneration with fibroblastic proliferation, a rare complication hitherto not reported with intravitreal or subconjunctival topotecan injections.