Clinical evaluation of suspected posterior uveal melanomas includes obtaining a history (eg, personal and family histories of cancer), performing a full ophthalmic examination, and ordering multiple types of imaging studies (multimodal imaging) (Figs 17-8, 17-9; see pp. 316–317). When used appropriately, the tests described in this chapter enable accurate diagnosis of melanocytic tumors in most cases. Atypical lesions may need to be characterized via other testing modalities, including intraocular biopsy (see discussion later in this chapter and also in Chapter 3); alternatively, when appropriate, these lesions may be closely observed for characteristic changes in clinical behavior in order to establish a correct diagnosis.
The most important diagnostic technique for evaluating intraocular tumors is indirect ophthalmoscopic examination. It provides stereopsis and a wide field of view and facilitates visualization of the peripheral fundus, particularly when performed with scleral depression. Indirect ophthalmoscopy and wide-field fundus photography enable clinical assessment of tumor size and surface features. Slit-lamp biomicroscopy in combination with gonioscopy is the best method for clinically establishing the presence and extent of anterior involvement of the tumor (see Fig 17-7C), although high-frequency ultrasound biomicroscopy (UBM) also allows excellent visualization of anterior ocular structures (see Figs 17-1, 17-2). In addition, slit-lamp biomicroscopy enables a detailed assessment of surface features of posterior tumors, including the presence of lipofuscin, subretinal fluid, retinal tumor invasion, and vitreous involvement.
Multimodal imaging is the standard of care in the diagnosis and ongoing management of melanocytic tumors. Fundus photography is valuable for documenting the appearance of a choroidal tumor (see Figs 17-6A, B and 17-8A, B) and for identifying changes in its shape and basal dimensions over time (see Figs 17-6C, D and 17-8A, B). Wide-angle (60°–200°) fundus photographs (see Figs 17-6C, D and 17-9A, B) can reveal the full extent of many tumors and document their relationship to intraocular landmarks. Comparison with the optic disc can aid in approximating the size of tumors. The relative position of retinal blood vessels may be helpful markers of changes in the size of a lesion. Fundus photographs also allow clinicians to use intrinsic scales to measure the basal diameter of a choroidal melanoma.
Fundus autofluorescence (FAF) imaging helps highlight lipofuscin, which is brightly autofluorescent (see Fig 17-9C, D). In addition, recent leakage of subretinal fluid produces increased autofluorescence, whereas long-standing or past leakage may result in decreased autofluorescence from secondary RPE atrophy. Enhanced depth imaging OCT or swept-source OCT is helpful in developing the differential diagnosis because it can reveal degenerative RPE and photoreceptor changes in long-standing lesions, which are less likely to be small melanomas, as well as lipofuscin and subretinal fluid in suspicious melanocytic choroidal tumors.
Fluorescein angiography findings are not pathognomonic for choroidal melanoma but can be helpful in differentiating between tumors and hemorrhagic processes that may mimic tumors. Indocyanine green angiography is not more accurate than fluorescein angiography for diagnosis, but it does often show alterations in choroidal blood flow in the region of the tumor. However, neither technique is commonly used in diagnosing melanoma.
Standardized ultrasonography is the most important ancillary tool for evaluating ciliary body and choroidal melanomas (see Fig 17-9E–H). The growth and regression of an intraocular tumor can be documented with serial examinations. Standardized A-scan ultrasonography (see Fig 17-9G, H) usually reveals a solid tumor pattern with high-amplitude initial echoes and low-amplitude internal reflections (low internal reflectivity). Spontaneous vascular pulsations can be demonstrated in most cases. B-scan examination provides information about the size (thickness and basal diameter), general shape, and position of intraocular tumors (see Figs 17-8G, H and 17-9E, F). B-scan ultrasonography is also the best technique for detecting posterior extrascleral extension associated with intraocular malignancies. Occasionally, tumor shape and associated retinal detachment can be evaluated more easily with ultrasonography than with ophthalmoscopy. B-scan ultrasonography typically shows a dome-shaped (see Fig 17-9E) or collar button–shaped (see Fig 17-9F) choroidal mass that has a highly reflective anterior border, acoustic hollowness, and choroidal excavation. A serous retinal detachment is often associated with larger tumors.
Figure 17-8 Multimodal imaging of choroidal nevi. A, B, Color fundus photographs document the tumor borders and surface appearance of 2 thin choroidal nevi. C, Fundus autofluorescence (FAF) reveals minimal RPE disturbance in the area of the choroidal lesion. D, FAF shows decreased autofluorescence centrally because of RPE loss as well as increased autofluorescence associated with more recent leakage, creating the appearance of a fluid gutter. E, Enhanced depth imaging optical coherence tomography (EDI-OCT) reveals no subretinal fluid associated with the lesion shown in parts A and C. F, EDI-OCT shows that the lesion shown in parts B and D has both numerous surface drusen and mild subretinal fluid (asterisk).G, H, B-scan ultrasonography reveals that both lesions are thin.
(Courtesy of Alison Skalet, MD, PhD.)
Figure 17-9 Multimodal imaging of choroidal melanomas. A, B, Wide-angle color fundus photographs document the tumor borders and surface appearance of 2 choroidal melanomas. C, FAF image of the lesion shown in part A reveals increased diffuse autofluorescence associated with subretinal fluid adjacent to the variably autofluorescent tumor (asterisk). Increased autofluorescence is associated with the lipofuscin (arrow).D, FAF image of the lesion shown in part B. The highly elevated tumor blocks under lying FAF. Diffusely increased autofluorescence is associated with subretinal fluid adjacent to the tumor (arrow).E, B-scan ultrasonography reveals the dome shape of the tumor shown in parts A and C. F, B-scan ultrasonography reveals the collar-button shape of the tumor shown in parts B and D. Images obtained from B-scan ultrasonography are helpful in measuring tumor size. G, H, Corresponding A-scan ultrasonographic image reveals a low, regular internal reflectivity associated with each melanoma.
(Courtesy of Alison Skalet, MD, PhD.)
Figure 17-10 Intraoperative localization of melanoma for treatment purposes. A, Transillumination of the eye reveals a shadow at the site of a choroidal melanoma. This technique may be used to mark the tumor base to ensure accurate placement of a radioactive plaque. B, B-scan ultrasonography after placement of the radioactive plaque confirms optimal positioning.
(Part A courtesy of Tero Kivelä, MD; part B courtesy of Alison Skalet, MD, PhD.)
The anterior location of ciliary body melanomas makes standard ultrasonography more difficult to perform (in contrast, high-frequency UBM, which does not share these limitations, enables excellent imaging of the anterior segment and ciliary body [see Fig 17-2G, H]). In addition, although ultrasonography is generally considered highly reliable in the differential diagnosis of posterior uveal melanomas, it may be difficult or impossible to differentiate a necrotic melanoma from a subretinal hemorrhage or a melanoma from an atypical metastatic tumor using this technology.
When high-frequency ultrasonography is not available, transillumination may be helpful in assessing the degree of pigmentation and in determining basal diameters of suspected ciliary body or anterior choroidal melanomas. The shadow of a tumor is visible with a bright, focused light source, preferably a high-intensity fiber-optic device, placed either on the surface of the topically anesthetized eye in a quadrant opposite the lesion or directly on the cornea, using a dark corneal cap. Fiber-optic transillumination is also routinely used to locate the uveal melanoma and delineate its borders during surgery for radioactive plaque insertion (Fig 17-10A). B-scan ultrasonography can be used after plaque placement to confirm appropriate positioning (Fig 17-10B).
Although computed tomography (CT) and magnetic resonance imaging (MRI) are not widely used to assess uncomplicated intraocular melanocytic tumors, they are useful in identifying tumors in eyes with opaque media and in possibly determining extrascleral extension as well as involvement of other organs. MRI may also help distinguish intraocular hemorrhage and atypical vascular lesions from melanocytic tumors.
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.