Retinoblastoma: Evaluation and Differential Diagnosis

In developed nations, the common presenting features of intraocular retinoblastoma are leukocoria and strabismus. Abnormal pupil reflex is also frequently observed in several pediatric ocular conditions, including cataracts, and it is important to clinically differentiate retinoblastoma from simulating diagnoses. For several reasons, retinoblastoma tends to be more advanced at presentation in developing nations. Misdiagnosis rates ranging from 16 to 53% in referral practices may be attributed to the rarity of retinoblastoma, the multiple conditions that simulate retinoblastoma, and the difficulty of examining children. As the diagnosis of retinoblastoma is clinical, careful evaluation of a child suspected to have retinoblastoma necessarily has to be thorough and conclusive so as to exclude simulating entities such as Coats' disease, persistent hyperplastic primary vitreous/persistent fetal vasculature, astrocytic hamartoma, toxocara, retinopathy of prematurity, and hereditary retinal disorders are common simulating conditions. Both eyes should be examined with an indirect ophthalmoscope after pupillary dilation to confirm a suspicion of retinoblastoma. Scleral depression may be withheld until examination under anesthesia (EUA). Ultrasonography can be attempted primarily to detect a retinal mass with calcification and neuroimaging (MRI of the brain and orbit with and without contrast) is performed to assess the orbital segment of the optic nerve and to detect pinealoblastoma (trilateral retinoblastoma). Fundus photos taken during the EUA with a wide-angle handheld fundus camera aids in assessing the response to treatment. Fluorescein angiography is particularly useful in differentiating retinoblastoma from Coats' disease.