Unilateral Multifocal Uveal Melanoma With Occult Ring Melanoma FREE

Unilateral multifocal uveal melanoma is a neoplastic curiosity that needs to be clinically distinguished from metastatic carcinoma and metastases of cutaneous melanoma. We describe a patient with a small posterior choroidal melanoma who developed 2 separate nonpigmented angle tumors in the same eye after treatment. The angle tumors simulated metastases of either the primary choroidal melanoma or an unrecognized systemic malignancy. When the eye was removed, we found an occult ring melanoma of the ciliary body with invasion of the angle.

A 71-year-old woman was referred for the evaluation of a pigmented tumor in her right eye. An examination revealed a visual acuity of counting fingers at 3 ft OD and 20/40 OS. Positive findings included bilateral cataracts and a 6-mm heart-shaped, pigmented choroidal tumor above the right optic disc (Figure 1A). A 3-mm flat, pigmented nevus was present temporal to the left macula. A standardized A-scan of the right choroidal tumor showed low internal reflectivity and a tumor height of 2.5 mm. A general medical evaluation and laboratory studies showed no evidence of systemic malignancy. The tumor was treated with a radioactive plaque. A week after surgery, 2 light-gray lesions approximately 1 mm in size were seen at the root of the right iris at the 7- to 8-o'clock and 10-o'clock positions (Figure 1B). The lesions were observed for 4 months but did not enlarge; an iris biopsy was performed and showed spindle melanoma cells. Further evaluation found no evidence of malignancy elsewhere, including the skin. The patient opted for removal of the eye. A histopathologic examination revealed a largely necrotic (>95%) choroidal melanoma above the optic nerve (Figure 2A). No mitotic figures were seen among the residual spindle and epithelioid cells. A mixed cell–type melanoma had encircled the ciliary body and focally invaded the angle (Figure 2B). When 40 fields were viewed under high-power magnification, 2 mitotic figures were seen. Both tumors were positive for the HMB-45 antigen. Results of serial sections confirmed that the 2 melanomas were not contiguous.

At least 16 cases of unilateral multifocal uveal melanoma have been reported in the literature.^1- 2 Our patient had no predisposing risks for uveal melanoma such as melanosis oculi or neurofibromatosis. She did not have bilateral diffuse uveal melanocytic tumors. The near-simultaneous recognition of both an anterior and posterior segment melanoma in the same eye is highly unusual.³ The time sequence in which 2 discrete anterior segment tumors were detected in our patient raised the possibility of ocular metastasis of either the recently treated choroidal melanoma or an occult systemic malignancy. Prior to biopsy, the second possibility seemed more likely because the angle tumors were nonpigmented. The ring melanoma, which was clinically undetected because of minimal elevation, probably represents a primary uveal malignancy.

The biological basis for multifocal uveal melanoma is unknown. The possibility of occult ring melanoma needs to be considered when multiple angle tumors are found, even in an eye harboring a discrete posterior melanoma.

Corresponding author: Curtis E. Margo, MD, MPH, Department of Ophthalmology, Watson Clinic LLP, 1600 Lakeland Hills Blvd, Lakeland, FL 33805 (e-mail: cmargo@watsonclinic.com).