Endophytic vs exophytic unilateral retinoblastoma: is there any real difference?

A retrospective review of 297 cases of enucleated and histologically proven unilateral retinoblastoma with a minimum of 5-year follow-up was analyzed to see if there were any clinical or prognostic differences between endophytic and exophytic type retinoblastoma. Endophytic retinoblastoma (181 cases) was found more often than exophytic (116 cases). The following features were not associated with the clinical appearance of either endophytic or exophytic tumors: sex of patient, right vs left eye, propensity for bilateral development, initial sign or symptom, presence of rubeosis, preoperative metastasis, optic nerve invasion, orbital recurrence, survival of the patient, length of follow-up, or age at diagnosis. Three features were found that correlated with type: a disproportionately higher percentage of patients with endophytic retinoblastoma had a positive family history; a disproportionately high percentage of patients with exophytic retinoblastoma developed glaucoma; and choroidal invasion occurred significantly more often in patients who had exophytic retinoblastoma than in those who had endophytic retinoblastoma.