RETINOBLASTOMA

Grouping: Clinical determination of the extent of disease with the focus being the eye. It is a preoperative evaluation with the main outcome being the salvagable status of vision or the eye.
Staging: It combines clinical, various imaging, and post-operative histopathological results to determine the extent of the disease. The main outcome is focused on the survival of the patient.

International Classification of Retinoblastoma ( grouping)[1]

Group A: Tumours smaller than 3mm or less

• Should be 2DD ( 3mm) from the fovea
• Should be 1DD (1.5mm) from optic nerve head

Group B: Tumours bigger than those in group A

• Located within 2DD from the fovea
• Located within 1DD from optic nerve head
• Localized cuff of subretinal fluid( < 5mm)
• No seeding is allowed in the group.

Group C: Localized tumor dissemination

• Vitreous seeding not more than 3mm from the base of tumor
• Subretinal seeding not more than 3mm from the base of tumor

Group D: Diffuse tumor dissemination

• Vitreous seeding may be any size and shape located away from the main tumor (>3mm)
• Subretinal seeding of any shape and size located 3mm away from tumor

Group E: Extensive disease

• Tumour touching the lens
• Diffuse infiltrating retinoblastoma
• Massive intraocular hemorrhage
• Neovascular glaucoma
• Pthisis or pre pthisical
• Anterior segment tumour
• Invasion of post laminar optic nerve, choroid, sclera, anterior chamber
• Orbital retinoblastoma

Regression patterns in retinoblastoma[3,4]
Type 0: Regression without remnant
Type 1: Regression with mainly calcified remnant
Type 2: Regression with no calcified component
Type 3: Partially calcified mass
Type 4: Flat atrophic scar

Types of vitreous seeds[5]
1) Dust: representing cellular infiltration
2) Cloud: representing tumour translocation
3) Spheres: representing clonal expansion of dust or cloud.

Regression patterns of vitreous seeds[5]
Grade 0: Regression without any trace
Grade 1: Regression with calcified or refringent residues
Grade 2: Regression with amorphous remnant with or without pigmentary changes
Grade 3: Combination of 1 and 2

Grading of melphalan related retinal toxicity[5]
Grade 1: salt and pepper retinopathy < 2 clock hours anterior to equator
Grade 2: salt and pepper retinopathy > 2 clock hours anterior to equator
Grade 3: salt and pepper retinopathy posterior to equator not involving the macula
Grade 4: : salt and pepper retinopathy involving the macula
Grade 5: Optic atrophy

Nugget: Mnemonic for factors predictive of iris naevus developing melanoma[6]
( ABCDEF guide)
A:Age < 40
B:Blood ( presence of hyphaema)
C:Clock hours ( inferior location)
D:Diffuse ( diffuse flat configuration)
E:Ectropion uvae
F:Feathery ( lesion having feathery geographic margins)

Classification of the ciliary body and choroidal melanoma[8,9]

Once the size of the tumor is established along with its extent, imaging modalities and laboratory investigations are performed to rule out metastasis. Tumour is then staged which provides a survival estimate which helps in prognosticating a case.
Category of ' T ' and then the approximate staging is inferred from charts provided from current TNM staging charts which are shown below.

Collaborative Ocular Melanoma Study ( COMS)[10]

COMS study was a path-breaking study, the results which dispensed some established ideas and provided the path for the future.
Although the name has ocular mentioned, the study looked into melanomas of only choroidal in nature. Major exclusion criteria's were:( readers are requested to go through the complete list of exclusion criteria from the referring source)

• Melanomas of iris and those involving anterior chamber
• Primary ciliary body melanoma
• Metastatic melanomas
• Extra scleral extension
• Diffuse melanomas

The study protocol can be understood by the following chart:

Important: Results

Enucleation versus plaque radiotherapy in medium-sized melanomas

• A maximal gain of visual acuity after plaque treatment occurred in the first year although they were not sustained.
• Factors associated with loss of visual acuity were greater tumor thickness, proximity to fovea, diabetes, shape of tumor
• 5-year failure rate of plaque was 10%.
• There was no difference in mortality rates between enucleation or plaque therapy.

Pre-enucleation radiation versus enucleation alone in large melanomas
There was no statistical difference between survival rates when enucleation alone was compared to pre enucleation radiotherapy

Reference