Calcification in retinoblastoma: Histopathologic findings and statistical analysis of 302 cases

Aim: To evaluate the histopathologic factors statistically associated with the presence of calcification in eyes with retinoblastoma. Methods: Retrospective, consecutive and observational case series. Three hundred and two enucleated eyes with retinoblastoma examined between the years 1960 and 2008. Five representative histopathologic slides of the pupil-optic nerve section and three cross optic nerve sections were retrospectively reviewed. The presence and degree of calcification as well as other histopathologic features were evaluated. Demographic data including age, gender and country of origin of the case were also reviewed. Univariate and multivariate statistical analyses were performed to search for a possible correlation between calcification and the other histopathologic factors and/or demographic data. Results: Calcification was present in 84.9% of cases. Age, tumour size, necrosis, basophilic staining, iris neovascularisation, choroidal, scleral and/or optic nerve invasion were correlated significantly with calcification. Multivariate analysis showed a significant correlation between the presence of calcification and the amount of necrosis and choroidal invasion only. Conclusions: In this series, calcification was more frequent in cases with more necrosis and cases with choroidal invasion, a known poor histopathologic risk factor for metastatic disease. The possible clinical implication of the findings from this study deserves additional studies.