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 presen ted with long-standing blindness of her right eye due to diffuse intrastrom al brown corneal discoloration. Intervention: The patient underwent penetrating keratoplasty and the cornea l 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 ep ithelium and limbus, The corneal graft remained transparent, with best-corr ected visual acuity of 20/30, Twenty-two months after surgery, the tumor in volved the anterior chamber angle and the iris. Three years later, it cause d refractory glaucoma necessitating enucleation. The iris tumor did not ext end beyond the iris-lens diaphragm and showed the same cytologic features a s 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 an d the proliferation of the Schwann cells in neurofibromatosis provides addi tional support for this hypothesis.