Q. What is Retinoblastoma?

A. Retinoblastoma is the most common primary tumor of the eye that arises from the nuclear layer of the retina and accounts for about 3% of the cancers occurring in children younger than 15 years of age.

Q. How does it occur?

A. Retinoblastoma can occur in both hereditary (40%) and sporadic (60%) forms. Hereditary disease includes those patients with a positive family history and those patients who have inherited a germline mutation from an unaffected parent. It has been found associated with deletions or mutations of the "Retinoblastoma" gene on the q14band of chromosome 13. The germline form can manifest both as unilateral or bilateral disease. However, most unilateral disease are sporadic where as all bilateral diseases are hereditary. But, unilateral disease in an infant is more likely to be a hereditary condition. 95% of the diagnosed cases of Retinoblastoma occur before the age of 5 years.

Q. How does it present clinically?

A. The most common presentation is leucocoria (white eye or cat's eye reflex). Other manifestations include poor visual acuity, squint, painful inflamed eye, proptosis and retinal detachment.

Q. How is it diagnosed?

A. Retinoblastoma is diagnosed by examination of the eye under general anesthesia using an ophthalmoscope. Calcifications and vitreous seedings confirm the diagnosis of retinoblastoma. A MRI or CT scan should be done to check for intracranial extension of the disease. Routine bone marrow examination and CSF examination are not indicated except when suspicion of spread of tumor beyond the globe e.g. patients with abnormal CBC or extension of tumor beyond the lamina cribrosa on ophthalmologic examination.

Q. How is the tumor staged and why is staging necessary ?

A. For the purpose of treatment, retinoblastoma is divided into intraocular and extraocular disease.

Intraocular :- Tumor is localized to the eye, it does not extend beyond the eye or to other parts of the body.

Extraocular :- Tumor extends beyond the eye. It may be limited to the tissue around the eye, or it may spread to the CNS or other parts of the body.

Reese and Ellsworth have classified intraocular Retinoblastoma as follows :-

Group 1 - very favorable for maintenance of sight.

• Solitary tumor, smaller than 4 disc diameters, all at or beyond the equator.
• Multiple tumors, none bigger than 4 disc diameters, all at or beyond the equator.

Group 2 - favorable for maintenance of sight.

• Solitary tumor, 4-10 disc diameter in size, at or beyond the equator.
• Multiple tumors, 4-10 disc diameter in size, behind the equator.

Group 3 - Possible for maintenance of sight.

• Any lesion anterior to the equator
• Solitary tumor larger than 10 disc diameter, posterior to the equator.

Group 4- Unfavorable for maintenance of sight

• Multiple tumors, some larger that 10 disc diameter in size
• Any lesion extending anterior to the ora-serrata.

Group 5 - Very unfavorable for maintenance of sight

• Massive tumors involving more than one half of the retina.
• Vitreous seeding.

(About 90% of patients present with Group5 disease in one or both the eyes)