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

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 The clinical data of 104 enucleated eyes diagnosed with retinoblastoma were retrospectively reviewed, and the pathological re-examination of the enucleated eyes was conducted. 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). 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.