High risk histopathological factors in retinoblastoma in upfront enucleated eyes: An experience from a tertiary care centre of Pakistan.

Background & Objectives: The assessment of histopathological risk factors (HRFs) in retinoblastoma in upfront enucleated eyes is important in deciding treatment protocols. Limited data is available from the developing countries as very few studies were conducted on retinoblastoma. The study aims to report this data from Pakistan. Methods: This cross-sectional study included treatment naïve retinoblastoma patients who underwent upfront enucleation between 2017 to 2021. Various tumor characteristics i.e. laterality, size, histologic grade, anaplasia grade, growth pattern, extent and length of optic nerve invasion, pathologic staging, tumor involvement of ocular structures were assessed. High-risk factors such as involvement of anterior chamber, choroidal, scleral, extrascleral, and optic nerve were also noted. Results: A total number of 54 patients were enrolled, out of which 53.7% were females while remaining were males. Median age at presentation was 24 months. Unilateral tumor was seen in 92.6% cases. Most frequent histologic grade was G2 (64.7%) and moderate anaplasia was observed in 59.2% cases. Vitreous involvement was seen in (86.5%). Pathologic staging of most of the tumors was pT1 (39.2%). Assessment of high-risk factors revealed that optic nerve involvement (35.1%) was the most common finding with retrolaminar tumor invasion seen in 75% cases. Choroidal invasion (≤3mm) was seen in 55.6% of patients. Limited involvement of anterior chamber (3.8%), sclera (7.4%), and extrascleral (3.8%) tissue was also observed. Conclusion: The presence of high risk histopathological factors in enucleated eyes diagnosed with retinoblastoma are known to have a profound impact on the risk stratification as well as decision of future treatment plan.