Diffuse Iris Melanoma: Conservative Treatment with Proton Beam Therapy after Limbal Stem Cell Preservation or Enucleation?

Abstract

Objectives: Iris melanomas represent 2-3% of uveal melanomas; the diffuse variant accounts for approximately 10% of all iris melanomas. Different treatment modalities for diffuse iris melanomas (DIM) have been proposed depending on the local status as well as the age and general condition of the patient. Methods: This study is a single-centre retrospective case series describing the diagnosis, treatments and outcomes of DIM. Treatment consisted of enucleation or proton beam therapy (PT) of the whole anterior segment. Patients who were treated with PT benefitted from limbal stem cell preservation before irradiation. Results: Between 1996 and 2016, a total of 14 patients with DIM presented to our institution and were included in the database. The global survival was 86%. The median follow-up was 4.6 years (range 4 months to 15 years). Only 1 patient (7%) developed metastatic disease of the DIM (gastric location). No patient developed liver metastasis. Seven patients were treated by enucleation and 7 by PT after limbal stem cell preservation. After a conservative attempt, local tumour recurrence occurred in 2 patients at 2 years, requiring enucleation. The cornea was clear after irradiation in all patients. Cataract (n = 6) and glaucoma (n = 4) were the main complications after irradiation. Conclusions: DIM is a very rare tumour. The global survival is excellent. Conservative treatment with PT is an efficient alternative to enucleation and allows good local tumour control. Cataract and glaucoma are the main radiation-related complications, but the corneal status was excellent due to the stem cell harvest prior to radiotherapy.