Purpose: To determine the types and frequency of lesions that clinically simulate choroidal or ciliary body melanoma (posterior uveal melanoma; PUM).
Patients and methods: A review was conducted on cases of patients referred to the ocular oncology service from October 1978 through September 2003 with the diagnosis of possible PUM but who were subsequently diagnosed by the authors to have a simulating lesion rather than PUM. The type and percent of pseudomelanomas were tabulated and compared with findings of a similar study from our service on data collected before 1978.
Results: There were approximately 12,000 patients referred because of a lesion believed to be a PUM during the 25 years included in the data collection. Of these patients, 1,739 (14%) were found to have a simulating condition. There were 54 different conditions that simulated melanoma. The most frequent condition was choroidal nevus, accounting for 851 cases (49%) of the pseudomelanomas. This was followed by peripheral exudative hemorrhagic chorioretinopathy (139 cases; 8%), congenital hypertrophy of the retinal pigment epithelium (108 cases; 6%), hemorrhagic detachment of the retina or pigment epithelium (86 cases; 5%), circumscribed choroidal hemangioma (79 cases; 5%) and age-related macular degeneration (76 cases; 4%). Compared with the 1980 report, the rate of pseudomelanomas diagnosed as choroidal nevus increased from 26% to 49%.
Conclusion: A variety of lesions can simulate PUM. Suspicious choroidal nevus is still the lesion most difficult to differentiate from PUM. Most other pseudomelanomas account for a lower percent compared with findings from the prior study, suggesting that clinicians are now more familiar with the other pseudomelanomas and less likely to refer them to rule out PUM.