**4. American Joint Committee on Cancer (AJCC) classification**

The American Joint Committee on Cancer and the International Union Against Cancer (AJCC/UICC) created a TNM staging scheme system for RB [26, 44–46]. It has multiple updated editions where the 8th edition is the latest updated one [45]. It is considered one of the extraocular classification systems besides the International Retinoblastoma Staging System (IRSS) [47]. Unlike other staging systems, TNM and IRSS were developed by multiple specialists and medical centers worldwide [48, 49]. The TNM8 system is subclassified into clinical, pathological, and hereditary classifications which stand for cTNM, pTNM, and H, respectively [45]. Furthermore, pathological staging necessitates enucleation of the eye to classify primary tumor plus examining local extension or distant metastasis by biopsies or total resection if present. The pTNM categories are divided to pT, the histological staging of the primary tumor after biopsy or enucleation, pN stands for microscopic examination of lymph node biopsy, and clinical plus microscopic examination of distant metastatic lesions implies as M [45, 49]. However, on initial evaluation application of clinical or cTNM, subclassification is wildly used by ophthalmologist which subclassify the tumor burden to intraretinal, intraocular, advanced intraocular, or extraocular [47]. The clinical "cTNM" and hereditary "H" classification are beyond the scope of this chapter. Further details of pTNM classification and staging are demonstrated in **Table 1** [45].

The updated pathological TNM8 version emphasized the importance to define focal, massive choroidal invasion and scleral invasion in compression to previously published TNM7 and TNM6 staging system in 2009 and 2002, respectively [45, 46, 49]. Furthermore, newly updated TNM8 staging system officially released formal staging group for prognosis. It is subdivided into four stages assigned for both clinical and pathological classifications as seen in **Table 1** [45]. Guillermo reported poor disease-free survival in patients staged by the pTNM7 staging system due to omission of scleral invasion. The major event of disease-free survival was extraocular relapse [49].


*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 definitions.*

**101**

**Author details**

Heba Alsharif1

Riyadh, Saudi Arabia

Hospital, Riyadh, Saudi Arabia

, Hala Helmi2

provided the original work is properly cited.

There is no financial interest to disclose.

and Azza Maktabi3

1 Department of Ophthalmology, College of Medicine, King Saud University,

3 Department of Ophthalmic Pathology/Oncology, King Khaled Eye Specialist

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

2 College of Medicine, Alfaisal University, Riyadh, Saudi Arabia

\*Address all correspondence to: az-mak@hotmail.com

\*

*Histopathological Characteristics and Classification for Prognostic Indicators*

staging section. In addition, formal prognostic stages were added.

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

The authors would like to thank the College of Medicine Research Center, Deanship of Scientific Research, King Saud University, and King Khaled Eye Specialist Hospital for their academic support and for providing us with images.

*DOI: http://dx.doi.org/10.5772/intechopen.89410*

**5. Conclusions**

**Acknowledgements**

**Conflict of interest**

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

#### **Table 1.**

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