Two Cases of Giant Melanocytoma (Hyperpigmented Magnocellular Nevus)

Melanocytoma or hyperpigmented magnocellular nevus is a variant of melanocytic nevus that is most commonly seen in the optic nerve, but has also been reported to occur in the iris, ciliary body, choroid, sclera, and conjunctiva. We present two cases of giant uveal melanocytoma with histopathology. The first case occurred in a 10-year-old girl who presented with decreased vision in the right eye and a mushroom-shaped pigmented choroidal lesion measuring 15.5 mm in apical height. The lesion was abutting the lens but not causing a cataract. This was diagnosed as a choroidal melanocytoma on open scleral window biopsy. The second case was in a 68-year-old lady, referred for a left nasal pigmented choroidal lesion measuring 8 mm in apical height and having a mushroom configuration. The lesion grew to 8.6 mm in height and was complicated by a vitreous hemorrhage and rhegmatogenous retinal detachment and was treated with iodine-125 plaque brachytherapy. Subsequently, the treated eye became a painful phthisical eye and was enucleated. Histopathology confirmed melanocytoma with extrascleral extension but without malignant transformation. Features of melanocytoma and other very large cases reported in the literature are discussed.