Uveal Melanoma Masquerading as Pigment Dispersion Glaucoma

A 64-year-old white woman from an outside ophthalmologist had a history of pigment dispersion glaucoma unresponsive to medical therapy in the right eye. She was subsequently found to have a ciliary body melanoma and was sent to our ocular oncology clinic for further evaluation. The clinical course and outcome are described.

The visual acuity in the affected eye was 20/60 OD with an intraocular pressure of 38 mm Hg and an elevated lesion beneath the peripheral iris at the 2-o’clock position. The left eye was normal.

In the right eye, the peripheral iris and anterior lens capsule were covered by a fine dusting of pigment (Figure 1). There was a small amount of corectopia superonasally. On gonioscopy, the angle was narrowed superonasally and there was intense, homogeneous pigmentation of the trabecular meshwork for 360°. Her contralateral eye had a small iris nevus but was otherwise normal.

Dilated examination of the right eye revealed a mass involving the ciliary body and posterior iris at the 2-o’clock position. There was evidence of direct tumor extension into the angle in the area of narrowing. Transillumination revealed no evidence of a ring melanoma. The vitreous was clear and the posterior pole was otherwise normal.

High-frequency ultrasonography revealed a mass centered in the ciliary body with low internal reflectivity. The tumor measured 12.0 × 7.9 mm in basal dimension with a height of 3.3 mm.

The patient was diagnosed with a ciliary body melanoma involving the iris and angle with secondary melanomalytic glaucoma. The systemic workup results were normal. The eye was enucleated based on patient preference.

Histopathological analysis revealed a ciliary body melanoma of the mixed cell type. The tumor involved the iris root and angle with tumor seeding of the anterior segment. There was posterior extension of the tumor as well (Figure 2).

Although ciliary body melanomas are less common than their more posterior counterparts, the prognosis for metastases is worse. This is likely owing to the larger average size of the tumor at detection as well as the association with more malignant cell types.¹ Even with treatment, the rate of metastasis at 5 years is 28%.²

Ciliary body melanomas can remain hidden from the eye care provider owing to their location posterior to the iris. Patients often become symptomatic only after the tumor becomes large enough to cause cataract formation or lenticular astigmatism or to displace the crystalline lens.The tumor can also invade the visual axis. Most of these tumors are not detected until their height is greater than 7.0 mm.² Earlier diagnosis has the potential to reduce the risk of metastasis.

Secondary glaucoma is a well-known complication of uveal melanomas. It is more common in eyes with ciliary body involvement, occurring in up to 17% of these patients. The most common mechanisms for glaucoma in this setting include pigment dispersion and direct tumor invasion of the angle. Melanomalytic glaucoma occurs when macrophages engulf the uveal pigment and block the trabecular meshwork. Choroidal melanomas can also cause neovascular glaucoma or angle closure from forward displacement of the lens-iris diaphragm.³

Ciliary body melanomas with iris involvement have been treated successfully with whole anterior segment brachytherapy.⁴ Other treatment options include external beam radiotherapy, proton beam therapy, and enucleation.

In conclusion, we describe a patient with a ciliary body melanoma that was initially diagnosed as pigment dispersion glaucoma. This case represents an uncommon manifestation of a malignant choroidal melanoma. Given the potential benefits of earlier diagnosis of ciliary body melanomas, suspicion for this entity should be maintained in cases of unilateral glaucoma with heterochromia.

Correspondence: Dr Johnson, Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine, 2870 University Ave, Madison, WI 53705-3611 (davidjohnsonmd@hotmail.com).

Financial Disclosure: None reported.