Optic disc melanocytoma: Progressive size reduction and increase of vessel density

A 43-year-old Japanese female patient with a left eye optic disc melanocytoma (ODM) was followed for stability since 2006. In the first 11 years, fundus photography was used. During this period, the ODM appeared to show a mild size reduction [Fig. 1].[1] In 2017, swept-source optical coherence tomography (OCT) angiography (PLEX Elite; Carl Zeiss Meditec Inc., Dublin, CA, USA) was introduced in the evaluation.[1] Full retinal slab angiography signals were analyzed by Otsu’s method for OCT angiography image binarization using the ImageJ software. The margins of the ODM were then marked manually, and the vessel density (VD) was calculated. OCT and OCT angiography showed a progressive reduction of both the ODM area (from 2.61 to 1.98 mm2) and the maximal tumor height (from 975 to 682 µm) [Fig. 2]. The corresponding OCT angiography measurements showed a gradual increase of VD from 51.4% in 2017 to approximately 56% in 2021 and May 2023 [Fig. 2]. In the last visit in November 2023, the measured VD was 54.0% which, considering the variability of the method, cannot be considered as a clinically meaningful change compared to the immediate prior values. No significant correlation was found between ODM area and VD (−0.600; P = 0.242).Figure 1: Size reduction of the optic disc melanocytoma on fundus photographs between 2006 and 2023Figure 2: Swept-source OCT angiography images and the corresponding tumor area, maximum tumor height, and whole retinal vessel density values of the optic disc melanocytoma between 2017 and 2023. OCT = optical coherence tomographyDiscussion ODM is a heavily pigmented, nonmalignant melanocytic nevus located at the optic nerve head.[2] Over years, it may both increase and decrease in size, and malignant transformation may also occur.[3] Clinical follow-up is typically made with fundus photography. Recently, cross-sectional OCT and OCT angiography findings in ODM were presented, but these technologies have not yet been applied for long-term follow-up of the condition.[1,4,5] Our case suggests that in ODM size reduction, the primary change is not a reduction of the tumor’s vasculature or perfusion, and OCT and OCT angiography are suitable methods for the objective follow-up of ODM. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship: Nil. Conflicts of interest: There are no conflicts of interest.