Ocular ultrasound findings in optic disk melanocytoma

Abstract

Purpose: To describe the echographic characteristics of optic disk melanocytoma using a high resolution 10–20 MHz ophthalmic ultrasound. Methods: We conducted a 10-year retrospective review finding 9 cases with optic disk melanocytoma. The echographic studies were performed by the same experienced ophthalmologist. The form and density of the tumors were evaluated with B-scan ultrasound. Internal reflectivity and vascularity of the tumors were assessed with a standardized A-scan. Base (vertical and horizontal) and height of the tumor were obtained by using both ultrasounds AB modes. Results: The mean age at diagnosis was 43.88 years. There was no evidence of abnormal tumor vascularization in any of the cases. Mean (SD) vertical measurement of the base was 2.53 mm (±1.47). Mean (SD) horizontal measurement of the base was 2.49 mm (±1.03). Mean height (SD) was 1.52 mm (±0.88). Of the assessable cases, 78% had high internal reflectivity, the remaining 22% had medium-high internal reflectivity. All tumors’ internal structure was characteristically homogeneous. Mean follow-up was 33.6 months. Conclusion: Melanocytomas are small, benign tumors that are highly assessable by ocular ultrasound when their elevation surpasses 0.5 mm. In our study, the internal reflectivity ranged from high to very high, unlike other malignancies such as choroidal melanoma which tend to present with low internal reflectivity. The avascularity of the tumor is a common finding. Ultrasound is a remarkable tool that helps detect benign characteristics in a pigmented optic disk tumor and helps establish a more reliable diagnosis.

Keywords

• Melanocytoma
• Optic disk
• Ultrasound
• Internal reflectivity
• Retina