Nonfluorescent choroidal melanoma

Tumour fluorescence and tumour-associated fluorescence of choroidal melanomas

'Tumour fluorescence' occurs within the tumour itself and is inversely related to the degree of pigmentation of the tumour, whereas 'tumour-associated fluorescence' occurs within the retinal pigment epithelium and retina as a result of degenerative changes in these structures; these secondary changes can collectively be termed 'tumour-associated retinal pigment epitheliopathy'. Tumour fluorescence should be differentiated from tumour-associated fluorescence so as not to confuse naevus with melanoma and to facilitate the interpretation of angiographic changes after radiotherapy or photocoagulation of choroidal melanomas.

Amelanotic choroidal nevi

A review of 373 patients with presumed choroidal nevi revealed 19 (5.1%) to have largely or totally amelanotic nevi. All patients but one with amelanotic nevi were white, and all were 48 years of age or older. Each lesion was located posterior to the equator, had a mean diameter of 3.2 mm, and was less than or equal to 1 mm in elevation. Intravenous fluorescein angiography most often disclosed early and late hyperfluorescence, corresponding to the amelanotic areas of the nevus. No lesions were observed to grow during a mean 14-month follow-up period. The differential diagnosis of amelanotic nevi of the choroid is discussed and includes amelanotic malignant melanoma, cavernous hemangioma of the choroid, metastatic cancer to the choroid, posterior scleritis, choroidal osteoma, and hypopigmented congenital hypertrophy of the retinal pigment epithelium.

Current approaches to the diagnosis and management of choroidal melanomas

Although malignant melanoma of the uveal tract is well known as the most common primary intraocular malignancy, many questions exist regarding the best approach to its diagnosis and treatment. In the past, diagnosis has been made by direct ophthalmoscopy alone and errors resulting in unnecessary enucleation have been frequent. However, recent studies have shown that the adequate use of new techniques such as indirect ophthalmoscopy, fluorescein angiography, ultrasonography, and the 32P test can reduce the incidence of error substantially. A 12-step procedure for diagnosis utilizing these aids is outlined. Traditionally, enucleation has been accepted as the treatment of choice. However, with earlier and more accurate diagnosis, alternative treatments are being applied in selected cases. Although photocoagulation, irradiation, cryotherapy, diathermy and local resection of choroidal melanomas have been used with some success, these methods require further trial and followup before their value can be established. Techniques and indications for use of these procedures are discussed, and the complications and potential effectiveness of each is evaluated.

Nonfluorescent malignant melanoma of the choroid diagnosed with the radioactive phosphorus uptake test

A 57-year-old white woman presented with a small malignant melanoma of the choroid in the macular area of the right eye. The lesion failed to produce a visual field defect or to show fluorescence with angiography, but the radioactive phosphorus uptake(P) test was positive. Histologically, the retinal pigment epithelium was intact over the tumor and the sensory retina was normal. This unusual finding was the most likely explanation for the normal visual field. The intact retinal pigment epithelium over this nonfluroescent melanoma suggests that the destruction of the retinal pigment epithelium occurring with most choroidal melanomas may partially explain why these tumors usually demonstrate fluorescence. This case emphasizes the great accuracy of the P test for diagnosing small malignant tumors of the choroid, even before other popular diagnostic modalities indicate the malignancy of the lesion.