[Morphometric analysis of small retinoblastomas following combination chemotherapy].

To date, the nature of micro-level changes in retinoblastoma (RB) foci following combination chemotherapy (CT) remains poorly studied.

Purpose: This study analyzed the morphometric characteristics of small RBs in children who underwent combination CT.

Material and methods: The study included 31 patients - 17 girls and 14 boys (n=31) - who had undergone combination CT and transpupillary thermotherapy (TTT). The children's ages ranged from 1 to 20 months (mean 9.7±6.9 months). The average follow-up period was 60.8±4.6 months. Spectral-domain optical coherence tomography (SD-OCT) was performed for tumors located in the central parts of the ocular fundus and in the middle periphery.

Results: The mean tumor height (prominence) was 2154±29 µm, and the mean basal diameter was 7998±122 µm. Microcalcifications (n=5; 16.1%) and confluent calcifications (n=26; 83.9%) were visualized in the tumor stroma, producing "shadow track" effects in these regions; confluent calcifications were observed in 83.9% (n=26) of cases, while microcalcifications were detected in 16.1% (n=5). All examined tumors were highly reflective. The incidence of endophytic and exophytic growth patterns was 65.6% and 34.4%, respectively. Detachment of the neuroepithelium above the tumor and in adjacent areas was diagnosed in 6.5% of cases. Additional morphometric characteristics of small RBs following combination CT included the formation of calcifications and hyperreflective changes in the inner, middle, and outer tumor layers, perifocal areas, and adjacent choroid in the area of neoplasms.

Conclusion: This study is the first to investigate the morphometric changes in small RBs following combination CT. These findings may aid in selecting the optimal method, parameters, and timing of focal therapy for more effective destruction of tumor foci.