Leukocoria and retinoblastoma: Case

Framing the case

This fourteen-month-old boy has the classic presentation of an intraocular retinoblastoma detected by the parent and confirmed by the red reflex test. The white glow in the flash photograph, the cream-white reflex on the left and the normal orange-red on the right together make the leukocoria, and the framework that organises the case is the urgent referral, the RB1 tumour suppressor gene and the International Intraocular Retinoblastoma Classification. The first priority is the same-day referral to the ophthalmology service, because the delay of the weeks can convert the curable intraocular tumour into the lethal extraocular disease. [1][2]

Confirming the diagnosis

The ophthalmology service performs the examination under anaesthesia with the indirect ophthalmoscopy, the fundus photography and the measurement of the tumour. The ocular ultrasound is the first-line imaging, and it shows the intraocular mass with the calcification that is the hallmark of the retinoblastoma and that distinguishes it from the Coats disease and the persistent fetal vasculature. The contrast-enhanced magnetic resonance imaging of the orbits and the brain defines the intraocular tumour, the optic nerve invasion, the extraocular extension and the pineal or the suprasellar mass of the trilateral retinoblastoma. The computed tomography is avoided because of the radiation and the second-malignancy risk in the heritable disease. [1][8]

The differential diagnosis

The retinoblastoma is distinguished from the long list of the leukocoria causes on the location and the associated features. The congenital cataract has the opacity within the lens itself, visible at the naked eye. The Coats disease is the retinal telangiectasia with the exudative detachment of the older boy, and it does not calcify. The persistent fetal vasculature carries the microphthalmia, the shallow anterior chamber and the retrolental fibrotic mass. The toxocariasis is the nematode granuloma of the older child exposed to the puppy, and the retinal coloboma is the sectoral defect of the inferior retina. The intraocular calcification on the ultrasound settles the question in favour of the retinoblastoma. [1][3]

Classification and treatment

The disease is assigned the International Intraocular Retinoblastoma Classification group, and the risk-adapted treatment follows. The goals are the cure of the life first, the salvage of the eye second and the preservation of the vision third. The focal therapy with the laser photocoagulation, the transpupillary thermotherapy and the cryotherapy treats the group A and the consolidation after the chemotherapy. The ophthalmic artery chemosurgery delivers the melphalan and the topotecan directly into the ophthalmic artery through the femoral catheter, at approximately three to five milligrams of melphalan per eye per session, repeated every three to four weeks for two to six cycles, and it salvages the group C and D eyes with the low systemic exposure. The systemic chemotherapy with the carboplatin, the etoposide and the vincristine treats the advanced intraocular, the extraocular and the high-risk histology. The enucleation removes the group E unsalvageable eye and allows the histology that guides the adjuvant chemotherapy for the high-risk features. [1][10]

Contrasting the bilateral heritable disease

The examiner asks the candidate to contrast this unilateral case with a child who presents with the bilateral retinoblastoma and the affected father. The bilateral disease is the heritable germline RB1 mutation, passed with the near-complete penetrance and the fifty-percent offspring risk, and it presents earlier, often in the first months of life. The genetic counselling addresses the diagnosis, the offspring risk, the prenatal and the preimplantation testing, and the lifelong surveillance for the second malignancy, including the osteosarcoma, the soft-tissue sarcoma, the melanoma and the brain tumour. The at-risk infant of the affected parent is enrolled in the surveillance from the birth, with the examinations under anaesthesia that detect the tumour before the leukocoria. The trilateral retinoblastoma, the primitive neuroectodermal tumour of the pineal or the suprasellar region, is the feared intracranial complication, and the routine brain magnetic resonance imaging is the standard for the heritable disease. [4][7][8]

Communication and the family

The family is counselled honestly and with the realistic information about the diagnosis and the prognosis. The candidate names the retinoblastoma, explains that the intraocular disease carries the survival above ninety-five percent with the specialist treatment, and that the treatment runs through the focal therapy or the chemosurgery over the several months. The parents are introduced to the multidisciplinary ocular oncology team, given a written plan, taught the examination under anaesthesia schedule, and supported by the social work and the educational liaison. The genetic testing is begun, and the offspring counselling and the surveillance for the heritable disease are integrated into the plan. [1][4]