Recurrent choroidal melanoma after brachytherapy in an eye with scleral calcification

Editor,

A 73-year-old-woman was referred to the Liverpool Ocular Oncology Centre for treatment of a symptomatic choroidal melanoma in the right eye, the lesion being discovered when blurred vision occurred.

The right fundus showed an infero-temporal choroidal melanoma extending to the fovea. On ultrasonography, the tumour measured approximately 15 × 14 mm basally with a thickness of 5.2 mm. Underlying scleral calcification was noted, which cast a shadow into the orbit (Fig. 1A, B). This finding was disregarded in treatment planning and the patient underwent brachytherapy with an eccentrically placed 20- mm ruthenium plaque. A mattress suture was used to ensure good apposition to the sclera. The plaque was removed after 60 hr, thereby delivering 531 Gy to the sclera and 80 Gy to the tumour apex. One year later, the tumour thickness diminished to 3.2 mm. Visible choroidal atrophy surrounding the tumour indicated that the plaque had been positioned adequately (Fig. 1c).

Figure 1.  (A, B) Longitudinal and transverse preoperative B-scan ultrasonography showing scleral calcification beneath the tumour, casting a shadow into the orbit. (C) Posttreatment choroidal atrophy surrounding the tumour indicating adequate positioning of the plaque. (D) Haemorrhage at the tumour margins 7 years after the plaque treatment.

Seven years after brachytherapy, the patient presented with vitreous haemorrhage and ultrasonography showed an increase in the tumour thickness to 5.2 mm. Pars plana vitrectomy was performed and the patient underwent proton beam radiotherapy.

Two years after proton beam radiotherapy, the tumour thickness was 3.5 mm but the patient developed a recurrent vitreous haemorrhage and neovascular glaucoma requiring enucleation.

Pathological examination showed a partially necrotic choroidal melanoma of epithelioid cell type, with vascular hyalinization from the radiotherapy. The mitotic count was 1/40 high power fields. Numerous macrophages were seen. The sclera adjacent to the tumour showed collagen degeneration and calcification (Fig. 2).

Figure 2.  (A) HE – low power magnification of the enucleated eye, demonstrating a partially necrotic choroidal melanoma with calcification in the adjacent sclera (×2 objective, dark blue/red). (B) HE – higher magnification of the choroidal melanoma and adjacent calcification in the sclera. Overlying the tumour is a fibrovascular layer and the retina, demonstrating degenerative changes (×10 objective). (C) HE – high power demonstrating viable melanoma cells within areas of necrosis (×40 objective). Viable cancer cells are commonly seen following various forms of radiotherapy: using additional immunohistochemical stains for different stages of the cell cycle, it is possible to determine whether these cells are still proliferating or in cell arrest. (D) MelanA stain – showing positivity of the tumour cells for this marker (APAAP, ×40 objective).

Apical tumour recurrence after ruthenium plaque radiotherapy is rare, even with eccentric plaque placement (Damato et al. 2005; Lommatzsch et al. 2000; Summanen et al. 1993). This case therefore raises the possibility that treatment failure occurred because of intrascleral calcification beneath the tumour. We suggest that this finding should prompt a higher dose of brachytherapy or an alternative form of radiotherapy, such as proton beam radiotherapy.