OBJECTIVES: Natalizumab is an effective therapy for multiple sclerosis. Its most notable toxicity is progressive multifocal leukoencephalopathy (PML).  The FDA mandated registry, TOUCH, focuses on reporting PML cases.  SONAR identified an unusual case of natalizumab associated urethral melanoma and queried FDA databases for all natalizumab associated melanoma events reported to the FDA.  We evaluated if safety reports were more complete among natalizumab associated melanoma cases when the safety report was reported from the TOUCH registry ("heavy TOUCH"), or when  data from TOUCH was used in the safety report sent to the FDA ("light TOUCH"), or if no data from TOUCH was included in the safety report ( "no TOUCH").  METHODS: Case details were obtained from MedWatch reports: 2005-2014.  A completeness score was developed, consisting of clinical (8 items), demographic (4 items), and pharmacy (3 items) - related items.  Clinical items include melanoma site, existence of pre-existing nevi etc.  Total completeness scores ranged from 0 (lowest) to 15 (highest).  Optimal discriminant analysis (ODA) was used to compare completeness across TOUCH groups.  As the TOUCH Registry is for the United States only, cases from outside the United States were evaluated separately.      RESULTS:  Overall, 137 melanoma cases were identified in MedWatch.  Of the US cases, 73% were categorized as light, 15% as heavy, and 13% as no TOUCH.  All median clinical completeness scores were low: 2.0, 4.0, 3.5, and 4.0 for heavy, light, no TOUCH, and non-US cases, respectively.  Statistical analysis revealed lower clinical completeness scores for heavy cases compared to the light cases (p<.0007).    CONCLUSIONS: FDA reports of natalizumab associated melanoma cases from the US generally contain 50% or less relevant clinical information.  The "heavy TOUCH" of the FDA-mandated registry did not facilitate improved completeness of reporting of natalizumab-associated melanoma, reflecting the focus on PML for the TOUCH program.