Uveal Melanoma Associated With Myotonic Dystrophy: A Report of 6 Cases.

Importance: Patients with myotonic dystrophy (MD) have an increased risk of malignancy including uveal melanoma. This case series further explores the association between these 2 diseases. Objective: To describe a cohort of patients with uveal melanoma associated with MD, including a case of iris melanoma, and MD-associated uveal melanoma in relatives. Design, Setting, and Participants: Retrospective case series at 3 tertiary referral centers (Wills Eye Hospital, Philadelphia, Pennsylvania; Mayo Clinic, Rochester, Minnesota; and Moorfields Eye Hospital, London, England), between January 1, 2000, and August 31, 2017. The study included 6 patients with MD and uveal melanoma. Main Outcomes and Measures: Melanoma response to treatment and development of metastatic disease. Results: There were 6 patients, 4 men and 2 women, with MD and uveal melanoma. The mean patient age at melanoma diagnosis was 47 years (median, 43 years; range, 30-67 years), and the tumor involved the choroid in 5 patients (83%) and iris in 1 patient (17%). The diagnosis of MD was known since young adulthood in 2 patients (33%) and was discovered in adulthood in 4 patients (67%). The main clinical features of MD included muscle weakness (n = 5; 83%), myotonia (n = 4; 67%), polychromatic cataract (n = 4; 67%), complications with general anesthesia (n = 4; 67%), myalgia (n = 3; 50%), cardiac arrhythmia (n = 2; 33%), and frontal baldness (n = 2; 33%). Genetic testing revealed MD type 1 (4 of 4 tested patients), and 2 patients demonstrated positive family history of MD with classic clinical features and preferred no testing. Melanoma treatment included plaque radiotherapy (n = 4; 67%), photodynamic therapy (n = 1; 17%), and declined treatment (n = 1; 17%). At follow-up of 6, 6, 41, 42, and 87 months (5 patients), findings included melanoma regression (4 of 5 tumors), melanoma recurrence (1 of 5 tumors), and no metastatic disease (5 of 5 patients). Conclusions and Relevance: Six adult patients with MD demonstrated uveal melanoma involving the choroid or iris, emphasizing the association between these 2 diseases. Further research seems warranted to explore the pathogenesis of uveal melanoma in MD. These findings support the consideration of ophthalmic examination for uveal melanoma in patients with MD.