Abstract
Purpose: :
To compare the immunoreactivity of pigment epithelium-derived factor (PEDF) between melanomas confined to the iris and melanomas involving either ciliary body or choroid.
Methods: :
After Emory University IRB approval was obtained, clinical and pathologic information from 34 patients with iris, ciliary body or choroidal melanomas were obtained from cases that had been accessioned in the L.F. Montgomery Ophthalmic Pathology Laboratory, Emory University. The specimens were routinely processed for light microscopic examination and 7µm thickness sections were stained with hematoxylin-eosin (H&E). Immunofluorescent staining was performed with pigment epithelium-derived factor (PEDF) and counterstained with propidium iodide (PI). The sections were evaluated on an inverted confocal Laser Scan Microscope. The distribution of PEDF was quantified using ImageJ software integrated density analysis. The correlations of immunoreactive intensity for PEDF protein between iris, ciliary body or choroidal melanoma respectively were analyzed by Mann-Whitney’s U test. The clinical pathologic findings, including PEDF staining, were compared.
Results: :
Of the 34 cases, 9, 10 and 15 had iris, ciliary body and choroidal melanomas, respectively. The average age of the patients was 56 years. 15 patients were male and 19 were female. The largest tumor size was 17 mm in basal diameter by 10 mm in thickness. Microscopic examination showed 8 melanomas were spindle cell type, 1 was epitheloid cell type, and 25 were mixed-cell type tumor. Quantitative analysis of immunofluorescence displayed a significant increase of PEDF expression within iris melanoma compared with ciliary body (248.14 ± 30.80 vs. 125.69 ± 30.33; P< 0.01 ) and choroidal melanoma (248.14 ± 30.80 vs. 101.69 ± 20.74; P< 0.001 ), respectively.
Conclusions: :
Iris melanoma is characterized by a high expression of PEDF compared with ciliary body or choroidal melanoma. This is consistent with the low grade clinical behavior of iris melanomas compared with ciliary body or choroidal melanoma.
Keywords: melanoma • pathology: human • immunohistochemistry