The relationship between tumor cell differentiation and age at diagnosis in retinoblastoma

Purpose: To determine the relationship between tumor cell differentiation and age at diagnosis in retinoblastoma. Methods: Medical records of 170 patients with retinoblastoma treated by enucleation were reviewed retrospectively. Age at diagnosis and histopathological features were analyzed. Results: Well-differentiated tumors presented earlier than poorly differentiated tumors. The frequency of presentation was highest in the first year of age for well-differentiated tumors and in the third year of age for poorly differentiated tumors (P < .0001). Bilateral well-differentiated tumors presented earlier than bilateral poorly differentiated tumors. Similarly, unilateral well-differentiated tumors presented earlier than unilateral poorly differentiated tumors. Conclusions: Differentiated tumors present earlier than poorly differentiated tumors, irrespective of laterality in retinoblastoma.