Differential diagnosis of iris melanoma. A, A pigment epithelial cyst (asterisk) can bow the iris forward focally. The cyst is visible after dilation. B, Multiple Lisch nodules in neurofibromatosis. Lisch nodules are melanocytic hamartomas that are typically tan to golden brown. C, Metastasis from a pulmonary carcinoma seen as an amelanotic mass on the temporal half of the iris and inside the pupil. The tumor distorts the pupil shape. D, Congenital ocular melanocytosis can cause a diffuse iris nevus but is associated with pigmented patches on the episclera and sclera ( arrows). Note the deeply pigmented, velvety stromal thickening in the iris.