Abstract
Purpose: To present 2 cases of large atypical melanocytomas that simulate melanoma. Methods: The largest risk factors for malignant transformation from melanocytoma into malignant melanoma are a combination of lesions with a thickness greater than 2 mm, visual symptoms, and tumor margin at the disc. The patients in this report were chosen because they both presented these factors with their lesions. Results: Because the lesions were properly identified as melanocytomas of the optic disc, the decision was made to monitor them closely and treat the associated vascular activity. Ultrasounds and close observations are key in differentiating these benign lesions from malignant melanomas. Conclusions: Both patients experienced long-term stability with intravitreal injections when needed for vascular activity.
Keywords: melanocytoma, edema, visual acuity, ocular lesion
Introduction
Melanocytoma is a rare benign tumor that presents as a densely pigmented ocular lesion. It usually remains stationary, although 10% to 15% of cases show mild growth. 1 It is often misdiagnosed as uveal melanoma because of its similar appearance; however, unlike melanocytoma, uveal melanomas are malignant, life-threatening tumors. The annual incidence of uveal melanoma in Europe and the United States is about 6 per 1 million population. 2 Transformation from melanocytoma into malignant melanoma is rare and estimated to occur in only about 1% to 2% of cases. 1 Treatment for melanocytoma requires lifetime observation to watch for malignant transformation. We present 2 cases of large atypical melanocytomas that simulated melanoma.
Results
Case 1
A 54-year-old man first presented in May 2018 with pigmented lesions in both eyes. The visual acuity (VA) was 20/15 OD and 20/150 OS. The intraocular pressure (IOP) was 14 mm Hg and 15 mm Hg, respectively. A dilated fundus examination showed a large, pigmented juxtapapillary lesion in the left eye with surrounding retinal pigment epithelium (RPE) hyperplastic alterations similar in appearance to bone spicules (Figure 1A). Ultrasonography showed calcification at the lesion surface and scattered within, with a maximum lesion height of 2.8 mm. Optical coherence tomography (OCT) showed macular edema with subretinal fibrosis (Figure 1B). The patient was diagnosed with choroidal nevus in the right eye and atypical melanocytoma and retinal edema in the left eye. The patient has received ongoing intravitreal bevacizumab injections in the left eye to treat the retinal edema. In addition, the eyes have had serial ultrasonography B-scans that have shown stability in both eyes for more than 5 years.
Figure 1.
Case 1. (A) Ultra-widefield imaging of the optic disc melanocytoma in the left eye with surrounding retinal pigment epithelium hyperplastic alterations. (B) Spectral-domain optical coherence tomography shows intraretinal edema and subretinal fibrosis.
Case 2
A 19-year-old woman presented in November 2018 with decreased vision and an optic disc lesion in the left eye. The VA was 20/20 OD and 20/200 OS, and the IOP was 14 mm Hg and 13 mm Hg, respectively. A dilated fundus examination showed a pigmented optic disc/peripapillary lesion with RPE hyperplastic changes similar in appearance to bone spicules (Figure 2A). OCT showed subretinal fluid (SRF) (Figure 2B). Ultrasonography showed an atypical thickness of 3.0 mm. The patient was diagnosed with melanocytoma of the optic disc and serous retinal detachment in the left eye. The patient was given repeated intravitreal bevacizumab injections, and the VA has improved to 20/40 in the left eye (Figure 2C). There has been no malignant transformation in the melanocytoma since the initial visit.
Figure 2.
Case 2. (A) Ultra-widefield imaging of the optic disc melanocytoma in the left eye with surrounding subretinal fluid (SRF) and retinal pigment epithelium hyperplastic alterations extending diffusely throughout the inferior fundus. (B) Spectral-domain optical coherence tomography of the macula shows SRF at the initial presentation and (C) resolution of the fluid after antivascular endothelial growth factor therapy.
Conclusions
Differential diagnoses of melanocytoma include juxtapapillary choroidal nevi, combined hamartoma of the retina and RPE, adenoma of the RPE, and vitreous hemorrhage. 1 Proper diagnosis of a melanocytoma is primarily based on the clinical findings during a fundus evaluation. After being properly assessed, the major concern when observing melanocytoma is transformation to melanoma. Uveal melanoma is the most common primary intraocular tumor in adults. 3 It is primarily found in White populations and is typically uncommon in Black and Asian populations. 4 Melanocytoma, however, seems to occur equally in all races and may have a preference for women. 5 There are various risk factors for melanoma, including fair skin, light-colored eyes, oculodermal melanocytosis (nevus of Ota), melanocytoma, and BRCA1-associated protein 1 (BAP1) tumor predisposition syndrome. 2
In addition, clinical risk factors may be associated with early choroidal melanoma transformation from atypical choroidal lesions. A large retrospective study by Shields et al 6 highlighted risk factors that include increased tumor thickness, presence of SRF, visual symptoms, orange pigment (lipofuscin), tumor margins adjacent to the optic disc, low reflectivity on ultrasound, an absence of a halo around the lesion, and an absence of drusen. The study also noted that the most dangerous combination of the risk factors was a thickness greater than 2.0 mm, visual symptoms, and tumor margin at the disc. This combination of symptoms was associated with a 69% risk for growth. 7 Both patients described in this case report presented with all 3 risk factors with their lesions; however, because they were properly identified as melanocytomas of the optic disc, the decision was made to monitor the lesions closely and treat the associated vascular activity.
Ultrasonography may assist in differentiating melanoma transformation from large melanocytomas without transformation. Melanocytomas usually show high internal acoustic reflectivity on A-scan, while low internal acoustic reflectivity is indicative of malignant transformation. 1
Melanoma treatment aims to preserve the eye, reduce the risk for metastases and, possibly, preserve visual function. Common treatment options for malignant melanoma are iodine-125 plaque brachytherapy and enucleation. 5 Radiation can achieve local disease control with early detection and early treatment. Enucleation is the method of choice when the tumor is significantly involved with the optic disc. 3 Because of this, when a melanocytoma shows clear transformation to melanoma, enucleation is the preferred treatment.
In conclusion, both cases in this report experienced long-term stability in the eye with intravitreal injections when needed for vascular activity. Ultrasounds and close observations are key in differentiating these benign lesions from malignant melanomas.
Footnotes
Ethical Approval: This research was conducted ethically in accordance with the World Medical Association Declaration of Helsinki.
Statement of Informed Consent: Informed consent was obtained before any diagnostic, therapeutic, or research activities were initiated.
The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: Dr. Murray is a consultant to Alcon and the Editor-in-Chief of the Journal of VitreoRetinal Diseases.
Funding: The author(s) received no financial support for the research, authorship, and/or publication of this article.
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