Abstract
Purpose :
Retinoblastoma (RB) is the most common intraocular malignancy in children. A small proportion of RB (2.3%) presents with intra-tumoral cavities that can be clinically detected by ultrasound and are more pronounced following tumour regression. Cavities in RB may be associated with a degree of differentiation of these tumours. However, this clinicopathological correlation has never been investigated. Histopathologically, well-differentiated RB shows numerous Flexner-Wintersteiner and Homer-Wright rosettes. The aim of this study is to assess the prevalence of cavitary spaces in retinoblastoma, and its correlation with the degree of differentiation, choroidal and optic nerve invasion.
Methods :
A total of 192 enucleated eyes from RB patients were analyzed. Histopathological features for each case were reviewed and the presence of choroidal involvement was noted along with invasion of the optic nerve (none, optic nerve head; ONH, or lamina cribosa; LC). The largest cavity diameter (mm) was also measured. The presence of rosettes was assessed in 60 selected cases, 30 with and 30 without cavities.
Results :
From the 192 cases, 28% (n=55) had one or several cavities. The average number of cavities was 3, with an average size of 2.18mm. Of those, 40% had choroidal invasion and 52% involvement of the optic nerve (LC n=18, ONH n=11). Similarly, 46% (n=63) of the non-cavitary RB showed choroidal involvement, and 77 tumours presented with optic nerve invasion (LC n=51, ONH n=26). The number of Flexner-Wintersteiner and Homer-Wright rosettes was significantly higher (average: 19.83 /10 hpf) in cavitary RB than in non-cavitary RB (P<0.005). There was no significant association between cavities and invasion of the optic nerve.
Conclusions :
To the best of our knowledge this is the first study correlating the presence and size of cavities in RB and the degree of differentiation. The prevalence of cavitary RB was higher than what has been clinically reported (28% vs 2.3%). Our results showed positive correlation between the presence of cavities and levels of RB differentiation. However, the presence of cavities, did not correlate to the invasion of the choroid or optic nerve. Clinical studies have suggested that cavitary RB shows resistance to treatment. Retinoblastomas with a high degree of differentiation show more cavities, suggesting that the resistance to treatment is related to the degree of differentiation of the tumour.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.