the International Classification System for Intraocular Retinoblastoma has been adopted, with the hope that it can better predict an eye’s response to chemotherapy. Eyes are grouped based on the size of the tumor and the presence of subretinal fluid, as well as the extent of vitreous and subretinal seeding. Eyes with anterior chamber involvement, neovascular glaucoma, vitreous hemorrhage, and/or necrosis are grouped as being unsalvageable (Table 19-5). The American Joint Committee on Cancer (AJCC) also has a staging system for retinoblastoma that relates to both intraocular and extraocular disease; see the staging form in the appendix.

Gallie BL, Truong T, Heon E, et al. Retinoblastoma ABC classification survey. 11th International Retinoblastoma Symposium, Paris, France; 2003.

Murphree AL. Intraocular retinoblastoma: the case for a new group classification. Ophthalmol Clin North Am. 2005;18(1):41–53. Reese AB. Tumors of the Eye. 3rd ed. Hagerstown, MD: Harper & Row; 1976:pp 90–132.

Shields CL, Mashayekhi A, Demirci H, Meadows AT, Shields JA. Practical approach to management of retinoblastoma. Arch Ophthalmol. 2004;122(5):729–735.

Table 19-4

Table 19-5

Associated Conditions

Retinocytoma

Retinocytoma is clinically indistinguishable from retinoblastoma. Chapter 11 describes the histologic characteristics that distinguish retinocytoma from retinoblastoma (Fig 11-44). The developmental biology of retinocytoma is subject to controversy. Some authorities consider retinocytoma to be retinoblastoma that has undergone differentiation, analogous to ganglioneuroma, the differentiated form of neuroblastoma. Many other authorities contend that retinocytoma is a benign counterpart of retinoblastoma.

Though histologically benign, retinocytoma carries the same genetic implications as retinoblastoma. A child harboring a retinoblastoma in one eye and a retinocytoma in the other should be considered capable of transmitting an RB1 mutation to offspring.