Histopathologic Risk Factors of Retinoblastoma: A Retrospective Study of 104 Enucleated Eyes

Purpose: To introduce a novel classification system for the extent of choroid invasion and to analyze the incidence of histopathologic risk factors (HRFs) in the patients with retinoblastoma in China Methods: The clinical data of 104 enucleated eyes diagnosed with retinoblastoma were retrospectively reviewed, and the pathological re-examination of the enucleated eyes was conducted. Results: Overall, the HRFs were present in 53% of the 104 eyes. For choroid infiltration, type 1 was observed in 38 eyes as isolated, sporadic tumor cells, or suspected tumor cells with no obvious choroid thickening; type 2 in 26 eyes, as localized nest-like or nidulant tumor cells without obvious choroid thickening; and type 3 in 25 eyes, as lumpish, massive or dense invasion with or without obvious choroid thickening. The mean follow-up period was 27.6 months (median, 24.9; range, 8.3-65.7). During the course of the study, four patients died of recurrence or metastasis. Statistically significant differences between the proportional mortality ratios were observed in choroidal infiltration of Type 3 (P=0.003), invasion of postlamina (P=0.033), sclera (P=0.003), and optic nerve resection line (P=0.005) cases. Based on univariate and multivariate analysis, leukocoria was negatively correlated with HRFs (P=0.001, OR=0.21; P=0.010, OR=0.25). Conclusion: Clinically, the novel classification system for the extent of choroid invasion could function as a practical definition for choroid infiltration, and the HRFs are present in a significant proportion of patients enucleated for retinoblastoma in China.