bubble_chart Overview

Retinoblastoma is a malignant tumor originating from embryonic retinal cells, with familial and hereditary tendencies. It predominantly occurs before the age of 3, often affecting both eyes, though rare cases can manifest in adulthood or even old age. Among ocular tumors, it ranks first in incidence, accounting for 33.8% of all eye tumors and 70% of intraocular tumors. Due to its high malignancy and potential for systemic metastasis leading to death, delayed diagnosis and treatment significantly increase risk factors. Therefore, early diagnosis is crucial. With timely detection and appropriate management, the cure rate can exceed 50%.

bubble_chart Clinical Manifestations

According to the tumor development process, it is often divided into four stages: ① Intraocular growth stage; ② Glaucoma stage; ③ Extraocular extension stage; ④ Metastasis stage.

In reality, the artificial staging only indicates the general progression of the tumor. However, tumors may not necessarily follow the above sequence. It is possible for a tumor to be very small and metastasize without causing increased intraocular pressure, or to develop to a certain extent and then spontaneously atrophy. Generally, in the early stages, it often begins from the posterior inferior part of the fundus, most commonly originating from the inner nuclear layer, appearing as many small gray-white nodules or larger white nodules surrounded by satellite nodules. Subsequent development is related to the origin of the tumor. Tumors originating from the inner nuclear layer protrude from the inner surface of the retina into the vitreous, often with coarse neovascularization or interspersed hemorrhagic spots. Flat-type tumors develop along the plane of the retina, with dilated and tortuous retinal vessels, resembling retinal hemangiomas. Regardless of how the tumor initially forms, once it grows to a certain size, it will eventually fill the vitreous cavity, displaying a yellow reflex resembling a cat's eye, hence the term "amaurotic cat's eye."

1. Intraocular growth stage: This varies depending on the tumor's location. If the tumor starts in the anterior part and grows slowly, it may preserve some vision for a considerable period. Conversely, tumors starting in the posterior pole often cause early vision loss, leading to eye deviation, so strabismus in children should not be overlooked or underestimated. If the retina is completely detached or the tumor fills the eyeball, visual function may be lost. Fundus examination reveals round, raised nodules on the retina, yellowish-white in color with clear borders, and neovascularization or hemorrhage on the mass.

2. Glaucoma stage: The intraocular mass enlarges and extends anteriorly and posteriorly, particularly involving the choroid and anterior chamber angle, often causing a sharp increase in intraocular pressure, presenting as acute angle-closure glaucoma. Due to the elasticity of the infant eyeball wall, high intraocular pressure can lead to so-called "buphthalmos" and scleral staphyloma. Highly enlarged and protruding eyeballs are prone to corneal ulcers and lens dislocation into the vitreous or anterior chamber. The child may experience eye pain, headache, and restlessness.

3. Extraocular extension stage: In this stage, the tumor can extend along the optic nerve posteriorly. ① Tumor invasion of the optic nerve is mostly a result of direct extension; ② In rare cases, tumor cells spread through the vascular ring of Zinn along the nerve sheath, entering the retrobulbar optic nerve via the subarachnoid space and pia mater, then progressing into the cranial cavity and invading brain tissue; ③ The tumor may exit the eyeball through the scleral canal, entering the orbit and rapidly enlarging behind the globe, causing proptosis. It may also break through the cornea and sclera anteriorly, forming a large mass incarcerated in the palpebral fissure.

4. Systemic metastasis: The tumor metastasizes throughout the body via blood and lymphatic systems. According to statistics, the most commonly affected organs are the brain and meninges, followed by cranial muscles, then lymph nodes and long bones, with the liver being the most frequently involved abdominal organ.

bubble_chart Diagnosis

Early diagnosis of retinoblastoma is extremely important, as it not only determines whether the eyeball needs to be enucleated but also relates to the patient's life. Sometimes, differentiation can be quite challenging, requiring comprehensive and meticulous inquiry and examination.

In most cases of retinoblastoma, typical clinical manifestations occur during its progression, and a diagnosis can generally be made based on medical history and clinical examination. The majority of patients are infants or young children, and a history of yellow light reflection in the pupil is often reported during the initial visit. Dilated pupil examination usually reveals multiple distinctive yellow-white or gray-white elevated masses on the retina, with dilated blood vessels or hemorrhage on the surface. The vitreous contains granular opacities of varying sizes. Ultrasound can detect solid masses, and if orbital X-rays or CT scans reveal fine calcified shadows, the diagnosis can be largely confirmed.

bubble_chart Treatment Measures

For unilateral and bilateral retinoblastoma, they should be managed differently. In unilateral cases, the eyeball should be enucleated as early as possible, with the severed optic nerve not shorter than 10 mm. If pathological sections show involvement of the optic nerve stump, orbital exenteration should be considered, supplemented by radiotherapy or chemotherapy. For bilateral cases, if one eye has already lost vision while the other retains some sight, the non-functional eye should be enucleated, and the other eye can undergo conservative treatment, including photocoagulation, cryotherapy, radiotherapy, or laser-hematoporphyrin therapy. If both eyes have lost vision, enucleation should be performed to save the patient's life.

bubble_chart Differentiation

Atypical cases are often misdiagnosed as other eye diseases in clinical practice, so careful differential diagnosis is necessary.

1. Metastatic endophthalmitis: At a certain stage of development, metastatic endophthalmitis may present a yellow reflex in the pupil due to the presence of vitreous abscess, which can easily be confused with the diagnosis of retinoblastoma. Since both diseases are relatively common eye diseases in young children, differential diagnosis between them is even more essential.

(1) One is an acute suppurative inflammation, always accompanied by some inflammatory manifestations to varying degrees. The other is a malignant tumor, not only with a longer course but also fundamentally different in presentation. For example, metastatic endophthalmitis often follows acute systemic infections, with obvious inflammatory reactions in the eye, including aqueous humor turbidity, deposits on the posterior corneal surface, posterior synechia of the iris, pupillary deformation, and secondary cataract caused by inflammation. Intraocular tumors generally do not exhibit these features.

(2) Tumor cases often lead to secondary glaucoma during their progression, causing corneal or whole-eye enlargement, whereas metastatic endophthalmitis results in eyeball atrophy within a relatively short period (about half a month to one month).

(3) Tumor masses protruding into the vitreous often exhibit neovascularization or hemorrhage, whereas the yellow reflex in metastatic endophthalmitis originates from pus in the vitreous, showing only yellow light without hemorrhage or neovascularization.

(4) Tumors rarely cause lens opacity, whereas intraocular inflammation frequently leads to cataract.

(5) On X-ray films, tumor cases often show calcification spots, and in rare cases, enlargement of the optic nerve foramen, whereas endophthalmitis patients do not exhibit these features. Although retinoblastoma often undergoes necrosis, it rarely causes inflammation.

2. Differential diagnosis between retinoblastoma and Coats disease: The fundamental nature of Coats disease is hemorrhage in the outer layers of the retina combined with exudative changes. Although localized proliferation may occur, even forming elevations or leading to retinal detachment, the disease progresses slowly, with relatively extensive lesions. Gray-white exudates are distributed behind the retinal blood vessels. In addition to exudates, hemorrhagic spots and shiny dots (cholesterol crystals) may also be observed. Blood vessels, especially veins, appear dilated, twisted, and tortuous, with microaneurysms. The disease is often progressive, with new and old exudates appearing alternately. If hemorrhage enters the vitreous, proliferative vitreoretinopathy may develop. Patients with this disease are older, mostly over 6 years of age, and predominantly young males, with unilateral involvement. Ultrasound examination often shows no substantial changes.