Retinoblastoma, [s8]uncommon

This uncommon, malignant, radiosensitive tumour of the embryonic cells of the retina usually presents before the age of two. It is bilateral in 25% of cases, and occurs in two forms, familial and sporadic. At first, the tumour enlarges within the eye; later it grows through the sclera, or chambers of the eye, to perforate the cornea. It can also spread through the optic nerve (where it may cause glaucoma) to the subarachnoid space. Familial cases are inherited as autosomal dominants. Healthy patients with one affected child have only a 5% risk of producing a second one. If a child survives, he has a high risk of transmitting the disease to his (or her) children.

The earliest sign is a squint or a fixed dilated pupil with a white reflection (''cat's eye'), and greyish white tumour visible with an ophthalmoscope. In the developing world, most children present late, with a large globe, and tumour penetrating the sclera or cornea.

RETINOBLASTOMA THE DIFFERENTIAL DIAGNOSIS varies with the stage of presentation, and is easy after glaucoma and intraocular extension have occurred. Before this, the diagnosis can be difficult, when all you can see is a white mass in an infant's vitreous. Dilate his pupils, and examine both his fundi under anaesthesia. Enquire for a family history.

Early Traumatic perforation of the globe. Traditional medicine in the eye. Retrolental fibroplasia, (history of prematurity and oxygen therapy).

Late A corneal ulcer leading to perforation, an anterior staphyloma (due to bulging of a weak cornea, 24.3). Panophthalmitis. Congenital glaucoma (24.6).

MANAGEMENT depends on the stage at which he presents.

If he presents early with the tumour confined to his globe (unusual in the developing world), refer him for radiotherapy, which cures 85% of cases. If you cannot refer him enucleate his globe (24.14).

If the tumour has extended through his globe, but not through the the wall of his orbit, his globe should be removed and radiotherapy given; his prognosis is so poor that a long journey to a referral hospital is not worthwhile. Consider removing his globe and giving him chemotherapy. If drugs and skills are short, his priority is low.

If he presents with proptosis and a fungating mass, exenteration (24.14) of his orbit will remove the mass, but is unlikely to prolong his life.

CHEMOTHERAPY. In 35% of cases the following regime causes a partial response, and in 65% it prevents progression for a while. Give him vincristine 1.4 mg/m['2]. And, doxorubicin (''Adriamycin') 50 mg/m['2]. And, cyclophosphamide 1 g/m['2]. Give all drugs intravenously once every 21 days.