Retinoblastoma is a hereditary or sporadic malignant tumor of the retina that occurs predominantly in children under 5 years of age. It is the most common intraocular tumor of childhood. The most common signs and symptoms are leukokoria and strabismus and sometimes, red eye, glaucoma and orbital cellulitis.
The following signs and symptoms present in patients with retinoblastoma:
The following tests are done to confirm and assess the extent of spread of the cancer in retinoblastoma among patients:
The treatment option available for retinoblastoma varies on the size, location and spread of the tumor. The following common treatment modalities are available for the treatment of primary and metastatic forms of Retinoblastoma:
Intraocular retinoblastoma which is treated early may garner a 90% survival rating. However, extraocular metastasis in retinoblastoma carries a poorer prognosis.
Patients with the inherited gene mutation have a higher likelihood to develop a second cancer in the affected eye and the irradiated region. Within a 30 year period from diagnosis, second cancers may develop in up to 70% of patients who survive. The more common second cancer observed are malignant melanoma and sarcomas.
The following clinical conditions may complicate from the primary retinoblastoma and from its post-radiation condition:
Retinoblastoma evolves from a gene mutation that triggers an uncontrolled cell division in the retina attributing for its carcinogenesis.
A modifier gene called MDM2 has been discovered to increase the catabolism of p53 and pRB in the chromosome 13 band . In half of retinoblastoma cases, patients may have family members with the gene mutation that presents with this type of eye cancer. Parents with retinoblastoma mutation gene increase the risk of their siblings to develop the cancer many folds over.
Retinoblastoma has an incidence rating of 0.5 to 1 case per 30,000 live births representing 3% of all cancers in childhood. It is commonly diagnosed among children from the age of 1 to 2 years old.
The worldwide occurrence scores at 11 cases per million children population occurring before the age of 5 years old representing 90% of all cases of retinoblastoma. In the United States, an estimated 250 to 500 new cases of retinoblastoma is diagnosed per year. Survival rating ranges from 86-92% but may subsequently drop with age. There is no predilection to either sex.
The pathophysiology of retinoblastoma revolves around its origin as a multi-potential precursor cell that may develop to either the inner or the outer endothelium of the retina. Theories postulates that the carcinogenesis in retinoblastoma arises from the photoreceptor cell layer of the retina . In retinoblastoma, gene mutations are identified in the locus of the long arm of chromosome 13 band 13q14.
Leading theories points to either endophytic spread of tumorous growth where it invades towards the vitreous humor by seeding, or by exophytic spread involving the backside of the retina spreading through the vessels and ciliary nerves. A diffuse infiltrating spread within the retina may rarely occur where only an infiltrating whitish discoloration is observed instead of an infiltrating mass.
As of 2007, studies conducted in St. Jude’s Research Hospital, Minnesota revealed that the progenitors of the retinoblastoma tumor may arise from matured horizontal interneuron cells explaining the rare pathology that may still express during adulthood .
The origin of retinoblastoma is still unclear and being currently researched; thus, actual prevention by modifiable factors in lifestyle isn’t possible yet. However, the genetic correlations found in retinoblastoma enables one to do genetic screening very early.
Massive drives of genetic screening may be performed amongst children to screen early detection of retinoblastoma and prevent the formation of the second cancer . Families with high risk of gene mutation may have their children’s eyes checked very early to spot the retinoblastoma at an early stage to afford excellent cure rate and save the normal vision of the affected eye.
Retinoblastoma is a common carcinoma of the eye that originates from the immature retina lining. Retinoblastoma usually affects young children but may rarely occur in adults. It may arise singly from one eye but it can simultaneously affect both concurrently.
Patients usually present with strabismus, inflammatory pain, impaired vision and leukocoria (white reflex in the pupils). Its occurrence is generally rare but it is known as the most common eye carcinoma. Retinoblastoma may spread to contiguous structures like the optic nerve and the brain, and may later metastasize to distant parts of the body .
Retinoblastoma is a gene mutation in chromosome 13 that causes uncontrolled cell division in the retina.
Retinoblastoma is diagnosed by direct ophthalmologic eye examination and confirmed through biopsy or imaging modalities.
Treatment and follow up
Small and early neoplasms may be treated with laser or cryosurgery. Extensive ones are subjected to a combination of chemotherapy and radiation therapy. Surgical enucleating of the eye orbit may be done when everything else fail. Patients should lookout for signs of metastasis after the treatments and report them immediately to their family eye doctor.