Iridocorneal melanoma associated with type 1 neurofibromatosis: A clinicopathologic study

Objective: A clinicopathologic study of an iridocorneal melanoma associated with type 1 (peripheral) neurofibromatosis is presented. Design: Case report with clinicopathologic correlation. Participant: A 32-year-old white woman with type 1 neurofibromatosis presented with long-standing blindness of her right eye due to diffuse intrastromal brown corneal discoloration. Intervention: The patient underwent penetrating keratoplasty and the corneal button was inspected. Results: Histopathologic evaluation of the corneal button after penetrating keratoplasty revealed an intrastromal mixed-type malignant melanoma, which stained positively with HMB-45 and S-100 protein and spared the corneal epithelium and limbus. The corneal graft remained transparent, with best-corrected visual acuity of 20/30. Twenty-two months after surgery, the tumor involved the anterior chamber angle and the iris. Three years later, it caused refractory glaucoma necessitating enucleation. The iris tumor did not extend beyond the iris-lens diaphragm and showed the same cytologic features as the corneal stromal tumor. Conclusion: To our best knowledge, this is the first report of iridocorneal melanoma associated with peripheral neurofibromatosis. The location of the tumor in the deep corneal stroma, without initial macroscopic involvement of the angle or iris, may suggest that the corneal portion of the tumor may have developed 'in situ' rather than as an extension of iris melanoma. The common origin of melanoma cells and Schwann cells from the neural crest and the proliferation of the Schwann cells in neurofibromatosis provides additional support for this hypothesis.