Intratumoral cavities in retinoblastoma: Prevalence and association with prognostic histopathological factors

Abstract Purpose: Retinoblastoma (RB) is the most common intraocular malignancy in childhood. Intratumoral cavities represent a rare clinical finding and have been scarcely investigated in large histopathological cohorts. This study aimed to determine the prevalence and morphological characteristics of cavitary RB and to evaluate their association with prognostic histopathological factors. Methods: A retrospective, cross-sectional histopathological study of 192 enucleated eyes with RB from a single ocular pathology center was conducted. Each case was assessed for the presence of intratumoral cavities, the number of cavities, and the largest cavity diameter. Choroidal invasion and optic nerve invasion (optic nerve head or lamina cribrosa) were documented. Results: Cavities were identified in 28.6% of eyes (55/192). Cavitary tumors showed a mean of 3.0 cavities per case and a mean maximum diameter of 2.18 mm (range, 0.5–6.3 mm). Choroidal invasion occurred in 40.0% of cavitary RBs (22/55) and in 46.0% of noncavitary tumors (63/137; P = 0.45). Optic nerve invasion was observed in 52.7% of cavitary RBs (29/55) and in 56.2% of noncavitary RBs (77/137; P = 0.66). Cavitary tumors exhibited well-differentiated components lining the cavities, including Flexner–Wintersteiner rosettes, Homer–Wright rosettes, and fleurettes. Conclusions: Cavitary RB was identified in nearly one-third of enucleated eyes, a frequency higher than that reported in clinical series, but without association with high-risk histopathological factors. These findings support the interpretation that cavitary RB is a well-differentiated morphological variant and provide a basis for future investigations on tumor differentiation, therapeutic response, and clinical outcomes.