Iris melanoma, clinical appearance. A, The lesion can be amelanotic with visible intrinsic vascularity. B, Alternatively, it may be densely pigmented, obscuring any blood vessels (note the dispersed pigment on the iris stroma). C–H, The slit-lamp (C, D), gonioscopic (E, F), and UBM (G, H) appearances of 2 iris melanomas are shown. The melanoma shown in parts C, E, and G is a small nodular tumor involving the anterior chamber angle; fine-needle aspiration biopsy revealed a melanoma composed of mainly epithelioid cells. The tumor shown in parts D, F, and H is a large amelanotic melanoma with prominent vascularity. Note the flat pigmented portion of the tumor (arrowheads in part F) along the edges of the mass surrounding the amelanotic portion.