Melanocytic stromal proliferations and nevi of the iris are the most common tumors of the iris, but melanoma is rare.[1,2] Clinical differentiation between an iris nevus and a melanoma might sometimes be difficult and at times may be impossible. Melanomas of the iris are usually small discrete lesions, although they may occasionally be diffuse, infiltrative, or multiple and may result in heterochromia, chronic uveitis, or spontaneous hemorrhage into the anterior chamber of the eye (hyphema). Iris melanomas that involve more than 66% of the angle circumference are associated with secondary glaucoma.
Routine evaluation of iris melanomas includes gonioscopy, transillumination of the globe, and indirect ophthalmoscopy with 360° of scleral depression. Photographic documentation is essential to document progression in size or growth of the tumor. Anterior segment fluorescein angiography may be helpful to demonstrate the vascularity of the lesion but is not diagnostic. High-resolution ultrasound biomicroscopy can be used to measure small lesions (basal dimensions and thickness) and to assess tumor involvement of the anterior ciliary body, angle, and overlying sclera. The main disadvantage with this technology is its limited penetration of large lesions. In these cases, conventional ultrasonography is more accurate.
In general, iris melanomas have relatively good outcomes. Only about 3% of these melanomas develop metastases within 5 years. Iris melanomas are predominantly of the spindle-cell type and are usually smaller in size than posterior melanomas. Clinical features, including prominent tumor vascularity, rapid growth, and heterogeneous pigmentation, are associated with an epithelioid cell component. Involvement of the iridocorneal angles is frequently associated with ciliary body invasion.
Given their rarity and good prognosis, trials with sufficient power are practical. Therefore, treatment experience is based principally on case series and case reports. Conservative management is generally advocated whenever possible, but surgical intervention may be justified with unequivocal tumor growth and with extensive disease at initial examination.
Standard treatment options:
- Observation with careful follow-up: In asymptomatic patients with stable lesions; follow-up includes serial photography.
- Local resection: When progressive and pronounced growth is documented.
- Enucleation: If the tumor is not amenable to local resection (diffuse involvement of the iris, involvement of more than 50% of the iris and anterior chamber angle, intractable glaucoma, and extraocular extension).
- Plaque radiation therapy: Offered as an alternative for large, diffuse, surgically nonresectable lesions of the iris.
Check for U.S. clinical trials from NCI's list of cancer clinical trials that are now accepting patients with iris melanoma. The list of clinical trials can be further narrowed by location, drug, intervention, and other criteria.
General information about clinical trials is also available from the NCI Web site.References
- Albert DM, Kulkarni AD: Intraocular melanoma. In: DeVita VT Jr, Lawrence TS, Rosenberg SA: Cancer: Principles and Practice of Oncology. 9th ed. Philadelphia, Pa: Lippincott Williams & Wilkins, 2011, pp 2090-8.
- Starr OD, Patel DV, Allen JP, et al.: Iris melanoma: pathology, prognosis and surgical intervention. Clin Experiment Ophthalmol 32 (3): 294-6, 2004. [PUBMED Abstract]
- Marcus DM, Sahel JA, Jakobiec FA, et al.: Pigmented tumors of the iris. In: Albert DM, Jakobiec FA, eds.: Principles and Practice of Ophthalmology. Philadelphia, Pa: WB Saunders Co., 1994, pp 3198-3208.
- Yap-Veloso MI, Simmons RB, Simmons RJ: Iris melanomas: diagnosis and management. Int Ophthalmol Clin 37 (4): 87-100, 1997 Fall. [PUBMED Abstract]
- Pavlin CJ, McWhae JA, McGowan HD, et al.: Ultrasound biomicroscopy of anterior segment tumors. Ophthalmology 99 (8): 1220-8, 1992. [PUBMED Abstract]
- Conway RM, Chua WC, Qureshi C, et al.: Primary iris melanoma: diagnostic features and outcome of conservative surgical treatment. Br J Ophthalmol 85 (7): 848-54, 2001. [PUBMED Abstract]
- Melanocytic tumors of the iris stroma. In: Shields JA: Diagnosis and Management of Intraocular Tumors. Saint Louis, Mo: C.V. Mosby Company, 1983, pp 83-121.
- Shields CL, Shields JA, De Potter P, et al.: Treatment of non-resectable malignant iris tumours with custom designed plaque radiotherapy. Br J Ophthalmol 79 (4): 306-12, 1995. [PUBMED Abstract]