**5. Conclusions**

*Retinoblastoma - Past, Present and Future*

**100**

*definitions.*

**Table 1.**

*Retinoblastoma is a subclassification composed of three aspects: pT, pN, and M. Pathological definition of primary tumor (pT): stands for histopathological staging of the primary tumor after biopsy or enucleation. Pathological definition of lymph node (pN): stands for microscopic examination of lymph node biopsy. Definition of distant metastasis (M): stands for grading distant metastatic lesions including both clinical and pathological* 

*The abovementioned aspects of pTNM are categorized to 4 stages demonstrated in the last part of* **Table 1***.*

*Pathological TNM classification and staging by the AJCC/UICC for retinoblastoma.*

Histopathological examination of RB cases is highly valuable in diagnosing, staging, and predicting prognostic factors and risk of metastasis. Further attention should be given while evaluating the four submitted block sections to detect highrisk features that indicate adjuvant chemotherapy administration that lowers metastatic rate and improves the survival rate. The high-risk features include retrolaminar optic nerve invasion, choroidal invasion, anterior chamber involvement, extraocular or extra-scleral spread. Moreover, incidences of previously mentioned high-risk features were studied in various articles. TNM staging created by AJCC/UICC provided pathological staging scheme for retinoblastoma. The recently released 8th edition in 2017 embedded choroidal and scleral invasion definition in tumor pathological staging section. In addition, formal prognostic stages were added.
