Clinical Examination

The presenting signs and symptoms of retinoblastoma correspond to the extent and location of the tumor. In the United States, the most common presenting signs are leukocoria (white pupillary reflex), strabismus, and ocular inflammation (Fig 19-1, Table 19-1). Other presenting features, such as iris heterochromia, spontaneous hyphema, and orbital inflammation, are less common and are associated with more advanced tumors. A small retinoblastoma tumor may be identified on routine examination, but this is rare and generally limited to patients who receive screening evaluations because of a family history of the disease. Known vision problems at presentation are uncommon because most patients are very young children who cannot yet express the vision loss.

Figure 19-1 Retinoblastoma. A, Clinical photograph shows leukocoria and strabismus associated with an advanced intraocular tumor. B, Higher-magnification view through the pupil. Note the large retrolental tumor and secondary total exudative retinal detachment.

(Courtesy of Timothy G. Murray, MD.)

An examination under anesthesia (EUA) is necessary for all patients suspected of having retinoblastoma in order to completely assess the extent of ocular disease prior to treatment. The intraocular pressures and corneal diameters of the eyes should be determined, and the iris should be evaluated carefully for neovascularization with a portable slit lamp. In addition, the locations of retinal tumors, the occurrence of subretinal fluid or exudative detachment, and the presence of either vitreous or subretinal tumor seeds should be ascertained bilaterally and clearly documented. Fundus photography and ultrasonography (echography) should also be performed to document findings and allow serial comparisons.

Retinoblastoma begins as a round, translucent, gray to white tumor in the retina (Figs 19-2, 19-3, 19-4). As the tumor enlarges, necrotic foci with calcification emerge, giving the tumor its characteristic chalky white appearance. Larger tumors contain dilated, tortuous intratumoral vessels. Exophytic tumors grow beneath the retina and often involve serous retinal detachment. As these tumors grow, the retinal detachment may become extensive, obscuring clear visualization of the tumor (Fig 19-5). Endophytic tumors grow on the retinal surface and into the vitreous cavity; therefore, blood vessels may be more difficult to discern in these tumors. Exophytic tumors cause subretinal seeding, whereas endophytic retinoblastoma tumors are more likely to yield vitreous seeds (Fig 19-6; see also Fig 19-4); these cells shed from the tumor remain viable in the vitreous and may eventually become implanted in ocular tissue, resulting in new tumor foci within the eye. Vitreous seeds also may enter the anterior chamber; there, they may aggregate on the iris as nodules or settle inferiorly as a pseudohypopyon formed of tumor cells, rather than inflammatory cells (Fig 19-7). Secondary glaucoma and rubeosis iridis occur in approximately 50% of eyes with advanced disease. Most advanced tumors have mixed endophytic and exophytic growth.

Table 19-1 Presenting Signs and Symptoms of Retinoblastoma

Figure 19-2 Retinoblastoma. Multiple tumor foci in an eye of a patient with a germline RB1 mutation.

(Courtesy of Matthew W. Wilson, MD.)

Figure 19-3 Retinoblastoma, clinical photograph. Discrete white macular tumor supplied by dilated retinal blood vessels.

(Courtesy of Timothy G. Murray, MD.)

Figure 19-4 Endophytic retinoblastoma. Note the growth into the vitreous cavity, dilated retinal blood vessels, foci of calcification (arrow), and cuff of subretinal fluid (asterisk).

(Courtesy of Matthew W. Wilson, MD.)

Figure 19-5 Exophytic retinoblastoma. Total exudative detachment due to tumor growth under the retina obscures tumor visualization. Note the normal-appearing retinal vessels, as opposed to those found in Coats disease.

(Courtesy of Matthew W. Wilson, MD.)

Diffuse infiltrating retinoblastoma is a rare variant of retinoblastoma that is detected later in childhood (>5 years) and typically presents unilaterally. Diffuse infiltrating retinoblastoma presents a diagnostic challenge because dense vitreous cells impede visualization of the retina, and there is no isolated retinal mass. This variant often is mistaken for an intermediate or posterior uveitis of unknown etiology. A clue supporting a diagnosis of retinoblastoma is that the seeds are in clumps of various sizes, and some seeds may be spherical, which is atypical of vitritis.

Excerpted from BCSC 2020-2021 series: Section 4 - Ophthalmic Pathology and Intraocular Tumors. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.