A case of choroidal melanocytoma treated by transscleral resection: A clinicopathological study

Abstract

Purpose: Choroidal melanocytoma is a rare benign melanocytic tumor. We report a case of choroidal melanocytoma that was definitively diagnosed by histopathological findings after local resection.

Observation: A 71-year-old female complained of blurred vision in her left eye. Her best-corrected visual acuity (BCVA) was 1.0. A dark-brown elevated lesion, measuring 5 papilla-diameter was found in the periphery of the fundus in her left eye. The mass showed hyperfluorescence on fluorescein angiography, early hypofluorescence and late hyperfluorescence on indocyanine green angiography. B-mode echography indicated the mass was originated from the choroid. Orbital magnetic resonance imaging showed isointense signal intensity on T1-weighted images (WI) and hypointense signal intensity on T2-WI, and poor Gadolinium enhancement on T1WI. The tumor was suspected to be melanocytoma, but it was difficult to differentiate from malignant melanoma. Transscleral tumor resection combined with 25-gauge vitrectomy was performed. Histopathological examinations led to the diagnosis of choroidal melanocytoma. Two years after local resection, her BCVA was 1.0 with no tumor recurrence.

Conclusions/importance: Local resection was useful as a diagnostic treatment for choroidal tumors confined to the periphery of the fundus that were difficult to clinically differentiate from malignant melanoma.

Keywords: Choroidal melanocytoma; Choroidal tumor; Histopathology; Local resection.

Fig. 1

Initial findings on color fundus photography (CFP), fluorescein angiography (FA), indocyanine green angiography (ICGA), B-mode echography, and orbital magnetic resonance imaging (MRI) in the present case with choroidal melanocytoma. A. CFP in the left eye showed a dark brown dome-shaped choroidal ridge on the temporal periphery, and there was no vitreous opacity or vitreous hemorrhage. B. FA detected hyperfluorescence in the choroidal mass from the early stage, suggesting RPE damage. C. ICGA showed hypofluorescence in the center of the tumor and hyperfluorescence at the periphery of the tumor in the late stage. D. B-mode echography displayed a prominent and substantial dome-shaped choroidal lesion. E.F.G. Orbital MRI demonstrated an orbital lesion with an isointense signal intensity on T1-weighted image (WI) (F), a hypointense signal intensity on T2-WI (G), and poor Gadolinium enhancement (H). H. Postoperative CFP showed scarring of the laser photocoagulation scars and no tumor recurrence.

Fig. 2

Intraoperative photographs in local resection of choroidal tumor. A. Creation of a 5 × 10 mm scleral flap centered on the tumor area. B. Exposure and incision of the deep sclera. C. After hemostasis with diathermy, resection of the choroidal mass along with deep sclera. D. Lens reconstruction combined with vitrectomy, intraocular laser around the tumor area, and sulfur hexafluoride gas injection.

Fig. 3

Pathological and immunostaining findings in the present case with choroidal melanocytoma. A. Total resection of the choroidal mass revealed dense, relatively uniform cells with large amounts of melanin granules (hematoxylin and eosin, 4 × magnification). B. Bleached preparation showed slight nucleolus manifestations, nucleus with mild irregular contour, and low nuclear-to-cytoplasmic ratio. Bar indicates 40 μm (40 × magnification). C. Human melanin black 45 (HMB 45) immunostaining was positive in tumor cells (10 × magnification). D. Melan A immunostaining was positive in tumor cells (10 × magnification). E. Sry-related HMG-Box gene 10 (Sox 10) immunostaining was positive in tumor cells (10 × magnification).