An Atypical Presentation of Optic Disc Melanocytoma: A Case Report.

Dear Editor, Optic disc melanocytoma is a unilateral benign tumor of the optic disc. Usually, the optic disc melanocytoma is asymptomatic and remains a stable flat dark pigmented juxtapapillary lesion throughout the patient’s life, and local complications, such as choroidal neovascularization (CNV), have been reported in less than 1% of the cases [1,2]. We describe a case report of a patient with an atypical presentation of an optic disc melanocytoma associated with CNV in which differential diagnosis of a malignant lesion was crucial to avoid unnecessary diagnostic or therapeutic procedures, such as radiotherapy. Informed consent for publication of the research details and clinical images was obtained from the patient. A healthy young man presented with progressive visual loss in the right eye (OD) over 2 months. Visual acuity (VA) was counting fingers in his OD and 20 / 20 in his left eye. Slit-lamp biomicroscopy findings and intraocular pressure were unremarkable bilaterally. Dilated fundoscopy of the OD revealed a peripapillary dark pigmented lesion surrounded by a halo of retinal atrophy, with a slightly elevated nodular portion, near the temporal border (Fig. 1A). There was also a macular edema and two subretinal hemorrhages located inferiorly to the macula. Optical coherence tomography (OCT) of the OD revealed distortion and elevation of the retinal layers towards the nasal macula, as well as an ill-defined subretinal lesion with heterogeneous internal ref lectivity near the optic disc and subretinal f luid (Fig. 1B, 1C). Ultrasonography showed a peripapillary elevated hyperechogenic lesion with a largest basal diameter of 3.18 mm and a thickness of 1.85 mm associated with shallow subretinal fluid (Fig. 1D, 1E). Differential diagnosis of the peripapillary lesion included optic disc melanocytoma with secondary CNV, choroidal melanoma, choroidal nevus, congenital hypertrophy of the retinal pigmented epithelium (CHRPE), and combined hamartoma of retina and retinal pigmented epithelium (RPE). Fine-needle biopsy is seldom necessary to distinguish between benign and malignant tumors, because ultrasound features and clinical examination yield high diagnostic accuracy. The presence of symptoms, subretinal fluid and proximity to the optic nerve are all risk factors predictive of choroidal nevus growth of and transformation into a choroidal melanoma, according to the Collaborative Ocular Melanoma Study (COMS) [3]. However, ultrasound features such as thickness <2 mm and base <5 mm (also according to the COMS), high internal reflectivity, and lack of acoustic hollowness (characteristic of melanoma), along with the juxtapapillary location and patient’s age, suggested a benign pigmented lesion. A combined hamartoma of the retina and RPE was excluded, because combined hamartomas are restricted to the retinal layers and combined hamartomas are usually nonpigmented lesions. On fundoscopy, the lesion could resemble peripapillary CHRPE, except for the lack of intrinsic atrophic areas, the associated CNV, and the 1.85 mm thickness measured on ultrasound, since CHRPE is almost always a flat asymptomatic lesion. Regarding treatment options, the best approach in this case was to treat the exudation from the CNV with intravitreal injection of an antivascular endothelial growth factor (anti-VEGF). VA improved to 20 / 50 following three monthly injections of ranibizumab. On OD fundoscopy, macular edema and intraretinal hemorrhages were no longer visible (Fig. 1F). Macular OCT of the OD showed almost complete restoration of normal macular architecture, with macular edema resolution in the foveal area (Fig. 1G, 1H). The patient will be kept on appropriate follow-up to prevent recurrence of macular CNV and under surveillance for malignant transformation, requiring proton beam radiation. Optic disc melanocytoma is a variant of melanocytic nevus, a hamartoma composed of nevus cells with intense cytoplasmatic pigmentation and uniform sizes of cells and nuclei [1,2]. Although this lesion is often asymptomatic, local complications such as disc edema and retinal vascular Korean J Ophthalmol 2023;37(2):192-194 https://doi.org/10.3341/kjo.2022.0153