Leukocoria in children can result from many types of lesions, some of which masquerade as retinoblastoma (Table 19-2). The most common conditions that simulate retinoblastoma are persistent fetal vasculature, Coats disease, and ocular toxocariasis. Most of these conditions can be differentiated from retinoblastoma on the basis of a comprehensive history, clinical examination, and ancillary testing.
Persistent fetal vasculature
The most severe form of persistent fetal vasculature (formerly called persistent hyperplastic primary vitreous) is typically recognized within days or weeks of birth. The condition occurs unilaterally in two-thirds of cases and is associated with microphthalmia, a shallow or flat anterior chamber, a hypoplastic iris with prominent vessels, cataract with fibrovascular material adherent to the posterior capsule, and a retrolenticular fibrovascular mass that draws the ciliary body processes inward. On indirect ophthalmoscopy, a vascular stalk may be seen extending from the optic nerve head and attaching to the posterior lens capsule, or the remnants of a stalk at the capsule and optic nerve may be observed. Ultrasonographic findings that confirm that diagnosis include a microphthalmic eye (eg, short axial length) with persistent hyaloid remnants arising from the optic nerve head, usually in association with closed-funnel retinal detachment. This condition is not associated with retinal tumors, although small foci of calcification may be present. See also Chapter 10 in this volume and BCSC Section 6, Pediatric Ophthalmology and Strabismus.
Table 19-2 Differential Diagnosis of Retinoblastoma
Coats disease is clinically evident within the first decade of life and is more common in males. The Coats lesion is characterized by unilateral retinal telangiectasia associated with intraretinal yellow exudation without a distinct mass (Fig 19-13). The progressive leakage of fluid may result in extensive retinal detachment and neovascular glaucoma.
Figure 19-13 Coats disease. A, Clinical photograph demonstrating characteristic lightbulb aneurysms (arrowheads). Note the associated exudative retinal detachment with subretinal exudate (asterisk).B, Fluorescein angiogram showing classic telangiectatic vessels (arrowhead).
(Courtesy of Matthew W. Wilson, MD.)
On ultrasonography, retinal tumors are absent, and cholesterol accumulation is observed in the subretinal fluid. FA demonstrates the presence of telangiectatic vessels and areas of retinal ischemia. See BCSC Section 6, Pediatric Ophthalmology and Strabismus, and Section 12, Retina and Vitreous, for additional discussion.
Ocular toxocariasis is a parasitic infection caused by Toxocara canis or Toxocara cati that typically occurs in older children with a history of soil ingestion or exposure to puppies or kittens. Toxocariasis presents with posterior and peripheral granulomas and associated uveitis. The granulomas often have a slightly elevated, circumscribed appearance. Exudative retinal detachment, organized vitreoretinal traction, and cataracts may be present. Ultrasonographic findings include vitritis, retinal detachment, granulomas, retinal traction, and an absence of calcium. See BCSC Section 6, Pediatric Ophthalmology and Strabismus, and Section 9, Uveitis and Ocular Inflammation, for further discussion.
Retinal astrocytoma, or astrocytic hamartoma, generally appears as a small, smooth, white, glistening tumor located in the nerve fiber layer of the retina (Fig 19-14). Retinal astrocytoma may present as 1 or multiple lesions occurring unilaterally or bilaterally. In some cases, the lesion grows and calcifies, yielding a “mulberry” appearance. Astrocytomas occasionally arise from the optic nerve head; such tumors often are referred to as giant drusen. Retinal astrocytomas commonly occur in patients with tuberous sclerosis and may be found in patients with neurofibromatosis; however, most cases are not associated with phakomatoses. Clinically, this lesion can masquerade as a small retinoblastoma, but handheld OCT imaging can be used to demonstrate that the tumor is confined to the nerve fiber layer. See BCSC Section 6, Pediatric Ophthalmology and Strabismus, for more information.
Medulloepithelioma usually appears as an off-white mass arising from the ciliary body (Fig 19-15A). However, in rare instances, this lesion also has been documented in the retina and optic nerve. Medulloepithelioma may be benign or malignant, although the benign form is far more common. In most cases, this type of tumor becomes clinically evident in children aged 4–12 years, but it may also occur in adults. Smaller lesions may present with unexplained neovascular glaucoma accompanied by iris heterochromia. The tumor may erode through the iris root or grow along the lens zonular fibers, extending into the anterior chamber. Diagnostic imaging may show large cysts on the surface of the tumor or within the lesion (Fig 19-15B). See Chapter 11 for a discussion of the histologic features of medulloepithelioma.
Figure 19-14 Retinal astrocytic hamartomas, clinical photograph. Note the more subtle opalescent lesion (between arrows) superonasal to the optic nerve head and the larger “mulberry” lesion that is inferonasal to the nerve head.
Figure 19-15 Medulloepithelioma. A, Pigmented lesion arising in the ciliary body, with an amelanotic apex (asterisk). The presence of melanin in these tumors is rare; most tumors are off-white to cream colored. B, T1-weighted magnetic resonance imaging with gadolinium; the image shows diffuse enhancement and multiple cystic spaces.
(Courtesy of Matthew W. Wilson, MD.)
Management of medulloepithelioma usually consists of enucleation or observation. Small lesions have been successfully treated with plaque brachytherapy, but in most eyes that have received this treatment, progressive degeneration eventually occurs, leading to enucleation. For most medulloepitheliomas, local surgical resection is avoided because of an association with late complications and metastases. Fortunately, metastasis is rare with appropriate management, even if the tumor appears frankly malignant on histologic examination.
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.