bubble_chart Overview

Uveal malignant melanoma is the most common malignant intraocular tumor in adults, ranking first in the incidence of intraocular tumors abroad and second only to retinal blastoma in domestic cases, making it the second most common intraocular tumor. This tumor is highly malignant and prone to metastasis through the bloodstream. It is relatively common in adults and can easily be confused with many fundus diseases in clinical practice. Therefore, it should be given full attention in ophthalmic clinical work. This disease is more prevalent in middle-aged and older patients. The posterior pole of the eye is the most common site of occurrence, with the incidence decreasing progressively towards the anterior part.

bubble_chart Clinical Manifestations

Uveal malignant melanoma can develop both inward and outward. Outward development can lead to early extraocular spread, clinically presenting as proptosis with minimal changes in the fundus. Inward development causes a spherical elevation beneath the retinal membrane, progressing rapidly with a short course, early visual impairment, and extensive retinal detachment, which is a relatively common clinical presentation. A rarer type spreads along the choroidal membrane plane, forming diffuse, flat proliferation without localized elevation. This type progresses slowly, has a long course, and is easily misdiagnosed as fistula disease. The various types are described as follows:

Choroidal malignant melanoma, constrained externally by the sclera and internally by the vitreous membrane, initially spreads along the choroidal surface. Before the vitreous membrane is breached, the tumor appears as a flat ellipse with minimal elevation and little change in the overlying retina, progressing slowly. Once the vitreous membrane is breached, the tumor rapidly expands in the subretinal space, forming a typical mushroom shape with a broad base, rounded head, and narrow neck. The tumor head may develop numerous blood sinuses due to impaired blood return, and rapid growth with insufficient blood supply can lead to necrosis and hemorrhage. At this stage, the retinal elevation is more pronounced, and the extent of retinal detachment gradually increases. The tumor apex, closely adherent to the retina, is less likely to detach. In rare cases, the tumor breaches the overlying retina, exposing it to the vitreous.

Intraocular pressure is initially normal or low, but in most cases, it increases as the disease progresses. If the tumor originates near the scleral aqueduct, extraocular spread often occurs before intraocular pressure rises. Conversely, if the tumor is near the vortex veins, intraocular pressure may increase even when the tumor is small. Finally, with extensive tumor necrosis causing severe inflammatory reactions, the eye rapidly atrophies, and intraocular pressure becomes low.

Ciliary body malignant melanoma can present differently depending on its location. Anterior growth can easily cause increased intraocular pressure and iridodialysis, while posterior growth can lead to peripheral retinal detachment, clinically resembling central retinal disease or optic neuritis. Without pupillary dilation, misdiagnosis or fistula disease diagnosis is common. Tumors growing centrally from the ciliary body can compress the lens, causing displacement or dislocation. Early extraocular spread may present as a mass beneath the anterior bulbar conjunctiva.

Intraocular spread of uveal melanoma along the optic nerve is rare, but systemic metastasis via the bloodstream is more common. The liver is the most frequent site of metastasis, followed by subcutaneous tissue and lungs, with possible central nervous system involvement. The metastasis rate is related to the tumor cell type, being highest in epithelioid cell types and lowest in spindle cell types. If reticular fibers are used as a measure, higher reticular fiber content correlates with lower metastasis rates, while lower reticular fiber content correlates with higher metastasis rates.

bubble_chart Diagnosis

Uveal melanoma is a highly malignant tumor, and early diagnosis is crucial. Timely treatment is essential to save the patient's life.

Diagnostic Basis

1. Choroidal malignant melanoma. Early symptoms include metamorphopsia, micropsia, central scotoma, and changes in refractive error (persistent increase in hyperopia), which are also important clinical manifestations, sufficient to indicate a substantial mass beneath the retina that is continuously growing. Early-stage choroidal melanoma at the periphery may not show obvious symptoms, but after retinal detachment, corresponding visual field defects appear. A special feature of melanoma located at the upper periphery is that it often combines with flat retinal detachment of the macula in the early stages of the disease. If the peripheral fundus is not thoroughly examined with dilated pupils, misdiagnosis is likely.

2. Since choroidal melanoma often originates from the ciliary nerves, fundus lesions may simultaneously present with abnormal pupils (non-reactive pupils in the corresponding area, difficult to dilate or not perfectly round), or a sector-shaped sensory reduction area may appear in the corresponding part of the cornea.

3. Scleral inflammation caused by blood flow obstruction or local tumor necrosis, manifested as localized scleral congestion. Granulation tissue proliferates inside and outside the sclera.

4. Eye pain. The pain may be caused by secondary glaucoma or tumor necrosis-induced inflammation (uveitis or endophthalmitis), and in a few cases, it is due to tumor infiltration or compression of the ciliary ganglion.

5. Anterior chamber or vitreous hemorrhage caused by tumor necrosis.

6. Exophthalmos caused by tumor spreading behind the eyeball.

7. Scleral transillumination test: It has significant diagnostic value. In inflammatory lesions, macular disciform degeneration, choroidal metastatic carcinoma, or choroidal hemangioma, light can pass through; however, in choroidal melanoma, it generally does not transmit light.

8. B-mode ultrasound scanner: B-mode ultrasound examination has important reference value and is particularly helpful in cases with turbid refractive media. The tumor appears as a smooth mushroom-shaped protrusion; there is an echo-negative area (acoustic shadow) behind the tumor on ultrasound, and the choroid is depressed.

9. Fluorescein fundus angiography

⑴ Retinal vessels and tumor vessels simultaneously show dual circulation.

⑵ No fluorescence in the early stage, increased fluorescence in the advanced stage, showing a mottled pattern of mixed high and low fluorescence.

10. Isotope³²Phosphorus absorption test positive.

11. CT and phosphorus resonance examinations are also helpful for diagnosis.

bubble_chart Treatment Measures

1. Surgery

(1) For those located within the eyeball, enucleation is performed. General anesthesia should be used during the surgery, and local anesthesia should be avoided to prevent the spread of tumor cells.

(2) For those that have spread outside the eyeball, orbital exenteration is performed.

2. For those that have spread outside the eyeball, orbital exenteration is performed.

bubble_chart Prognosis

The prognosis of uveal malignant melanoma is better than that of cutaneous melanoma, with a mortality rate of 50% for the former and up to 80% for the latter. Local recurrence or metastasis mostly occurs within 1 year after surgery, although in some cases it may extend to 5 years or more. The prognosis is closely related to the type of tumor cells, with spindle cell type having a lower mortality rate and epithelial cell type having a higher mortality rate.