Mini Review - (2023) Volume 13, Issue 2
The most common primary intraocular malignancy in adults is uveal tract melanoma, which accounts for about 5-10% of all melanomas. Uveal melanoma can only spread hematogenously, leading to liver metastasis, because there are no lymphatic vessels in the eye. There are numerous treatment modalities available for its management, making it difficult to choose the most appropriate therapy. This article examines the diagnostic and therapeutic modalities available, which can aid in tailoring a treatment plan for each patient. National Cancer Institute, Cairo University, 2016. Elsevier B.V. produced and hosted the video. This is an open access article distributed under the Creative Commons BY-NC-ND license.
Uveal tract melanoma • Collaborative Ocular Melanoma Study (COMS) • Immunosuppression
The most common primary intraocular malignancy in adults is Uveal Tract Melanoma (UVM), which accounts for about 5%-10% of all melanomas [1]. The male to female ratio is 1.3:1. The disease is uncommon in children and young adults, and its prevalence increases gradually with age, peaking at around 70 years [2]. At 10 years after diagnosis, the risk of distant metastasis in the well-known Collaborative Ocular Melanoma Study (COMS) was 34% [1]. In addition, the median time to death after a diagnosis of metastasis was six months [2]. Several risk factors for melanoma have been identified, including fair skin, blond or red hair, light-colored eyes, extensive freckling, and a family history of one or more types of cancer. Sunburns that are more severe, blistering, excessive ultraviolet (UV) light exposure, living closer to the equator or at a higher elevation, having >50 mol or atypical moles (dysplastic nevi), a family history of melanoma, and immunosuppression [3].
The uveal tract is made up of the iris, ciliary body, and choroid, and UVM can affect one or more of these structures. Ciliary body and choroidal melanomas account for approximately 95% of all UVM. Melanoma has been found in only 5% of Iris cases. Another distinguishing feature of iris melanoma is that it rarely spreads [4].
Melanoma is named after the melanocytes that gave rise to it. The amount of pigment in the lesion, however, varies, resulting in a color spectrum that is typically dark brown and black. Amelanotic melanoma in various parts of the body has been reported [4]. Recent research indicates a link between tumor pigmentation and the risk of growth and metastasis, with lighter pigmented or amelanotic lesions having a better prognosis. A typicachoroidal melanoma is characterized by a dark brown, elevated sub retinal mass. Calendar identified distinct cell types in the UVM cell population in 1931.
Cell size, shape, cytoplasmic features, loss of cohesion, nuclear and nucleolar characteristics all contribute to the modified Calendar classification. Spindle cell melanomas (30% of intraocular tumors), mixedcell melanomas (65%), when fewer than half of the cells in the sections examined are epithelioid cells, and epithelioid cell melanomas, when more than half of the cells in the tumor sections are epithelioid cells, account for 5% of UVM [5]. The pathologist's designation of a specific cell type is based on subjective judgement. UVM is typically restricted to the globe. Extrascleral extension can occur in larger tumors, with approximately 15% of cases showing extra-scleral extension. The optic nerve and the lumen of vortex veins are two other extraocular spread pathways [6]. UVM can only spread hematogenously because there are no lymphatic vessels on the planet. After 25 years of diagnosis, nearly 50% of patients have distant metastasis [7]. The liver is the most common site of distant metastasis (89%).
Diagnosis
Clinical Examination: UVM is frequently diagnosed clinically, with accuracy reaching 99.7% in specialized centers.
Ultrasonography: The combination of A- and B-mode techniques is critical in confirming the clinical diagnosis of choroidal melanoma with greater than 95% accuracy [7]. Choroidal melanoma has medium to low internal echoes with smooth attenuation on A-scan ultrasonography and vascular pulsations within the tumor. On a B-scan, choroidal melanoma has three classic features: an acoustically silent zone within the tumor, choroidal excavation, and orbital shadowing [8]. Furthermore, ultrasonography is a valuable tool for patient follow-up in patients receiving conservative treatment.
Photography: Fluorescein angiography can help distinguish melanoma from hemorrhage or hemangioma. In patients with melanoma, it usually causes irregular Hyper fluorescence in the early phase, followed by tumor staining in the late phase [7]. The orange pigmentation in the retinal pigment epithelium, on the other hand, usually blocks the early Hyper fluorescence. Larger melanomas may exhibit a patchy pattern of hypo fluorescence and Hyper fluorescence at first, followed by late intense staining. Some choroidal melanomas have intrinsic vascularization that can be seen throughout the angiogram.
The "double circulation pattern" angiographic sign refers to simultaneous fluorescence of retinal and choroidal circulation within the tumor. It is fairly distinctive of choroidal melanomas when it occurs [8]. Colored fundus photographs also play critical roles in the accurate assessment and followup of the lesion's basal dimension, as well as post-treatment.
The patterns of Indocyanine Green Video angiography (ICGV) vary depending on the degree of pigmentation, thickness, and vascularity of the tumor. In all cases, hypo fluorescence can be seen in the early frames of ICGV [9]. In some cases, intrinsic choroidal vasculature can be seen. Hyper fluorescence and three-ring patterns are seen in the late stages of ICGV.
Fine-Needle Aspiration Biopsy (FNAB)
Obtaining the pathology report before beginning definitive treatment is not always advised. When the clinical diagnosis is uncertain, diagnostic biopsy can be considered while weighing the risks of the procedure.
FNAB can be performed using either a trans scleral or a trans-virial approach. If the patient requests it, a prognostic biopsy is also considered. The current practice in the world's most advanced centers dealing with uveal melanomas is to obtain FNAB for cytogenetic studies of the tumor during treatment (plaque or enucleation) and in the few cases where the clinical diagnosis is in doubt.
Other diagnostic tools
Ocular Coherence Tomography (OCT) can help distinguish large choroidal nevi from melanomas [8]. Choroidal nevi have well-defined margins, are flat or slightly elevated, and remain stable in size. Choroidal melanomas, on the other hand, are more likely to exhibit activity-related characteristics such as relatively indistinct margins, irregular or oblong configuration, overlying subretinal fluid and orange pigment, and abruptly elevated edges. Magnetic Resonance Imaging (MRI) can be used to provide intraocular enhancement of the lesion, which may aid in predicting the degree of malignancy and monitoring treatment response.
Metastatic workup
Because melanoma has a high risk of distant metastasis, a comprehensive physical examination, imaging studies, and biochemical tests are required as part of the initial workup. In the staging process, abdominal ultrasonography, chest X-rays, and Computed Tomography (CT) of the head are all useful. According to the findings of the COMS study, liver function tests, followed by diagnostic tests, are highly specific and have high predictive values, but their sensitivity remains low [10]. Some hospitals use whole-body positron emission tomography/CT as part of the staging process [11]. The presence of tyrosinase or MelanA/MART1 transcripts has been shown to be an independent prognostic factor for metastasis development.
Staging
Staging is an important tool in predicting a patient's prognosis, but it should not be used to postpone primary tumor management. Whole-body staging (chest, abdomen, and pelvis) should be performed using a CT scan or PET-CT. Only in the presence of related symptoms are brain imaging and bone scans required. To assess resectability in patients with liver metastasis, contrast enhanced MRI with diffusion weight imaging is required. A contrast-enhanced CT scan is recommended for extrahepatic disease staging. COMS staging is widely used because it considers tumor thickness and basal diameter [12].
Management
The therapy selected for choroidal melanoma should be individualized and is dependent on various factors, such as patient’s age, tumor size and location, general health, and status of the fellow eye. However, there is no proven survival advantage between any of the offered modalities.
Small choroidal melanoma
The most important issue in the treatment of suspected small choroidal melanomas is determining when to begin definitive therapy. The authors advise that each case be treated as an individual. Transpupillary Thermal Therapy (TTT) and radiation therapy are two effective treatments [12]. Furthermore, an experienced clinician can use plaque radiotherapy to treat small uveal melanomas [13]. There is some debate about how to treat certain uveal melanomas. For instance, in the case of "small" AJCC T1 uveal melanomas, In the absence of thickness P2 mm, subretinal exudative fluid, and superficial orange pigment lipofuscin tumors, the American Brachytherapy Society (ABS)-Ophthalmic Oncology Task Force (OOTF) recommends that patients be offered the option of "observation" for evidence of change (within 6 months) typically for documented growth prior to intervention. This is especially important for tumors near the fovea and optic nerve, as well as monocular patients, where treatment is likely to result in radiation-related vision morbidity.
Laser photocoagulation therapy
Xenon arc photocoagulation was replaced by argon laser photocoagul ation, which showed fewer complications but less tumor control [13]. The major limitations of laser therapy include poor tissue penetration and the requirement for multiple treatment sessions. Hence, laser therapy has been superseded by TTT.
Transpupillary Thermal Therapy (TTT)
Infrared light (diode laser, 810 mm) is used as heat to induce necrosis in tumor tissues. The tumor recurrence rate was 10% at 3 years, with visual acuity worse than 20/200 in 32% of cases in the report [14]. The ideal candidate for TTT is small, heavily pigmented melanoma less than 3 mm thick with minimal or no subretinal fluid, located in the extramacular region but not touching the optic disk. Delayed recurrence and extrascleral extension are the important drawbacks of TTT. This treatment can be used as an adjunct to plaque radiotherapy.
Citation: Musiala, J. & Jones, F. A Comprehensive Review of Uveal Tract Melanoma Management. Prim Health Care, 2023, 13(2), 487.
Received: 07-Feb-2023, Manuscript No. JPHC-23-92136; Editor assigned: 10-Feb-2023, Pre QC No. JPHC-23-92136 (PQ); Reviewed: 24-Feb-2023, QC No. JPHC-23-92136 (Q); Revised: 25-Feb-2023, Manuscript No. JPHC-23-92136 (R); Published: 28-Feb-2023, DOI: 10.35248/2376-0389.23.13.2.487
Copyright: ©2023 Musiala, j. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
