Cutaneous T-cell lymphoma (CTCL) is a major form of the primary cutaneous lymphomas and affects all populations in the world including the American and Chinese. CTCL symptoms range from mild itchy red patches to large, painful, disfiguring nodules, and patients with the advanced stages of CTCL only have up to a 50% three-year survival rate. CTCL patients respond differently to current available treatments, and the subtypes (e.g. Sezary syndrome) vary greatly in their relapse-rate and prognosis. While we and others have conducted population-specific genetic, epidemiological, and/or molecular studies, there has not been any cross-ethnic study to systematically evaluate the shared/unique risk factors associated with prognosis cross populations. With CTCL being an uncommon cancer with limited armamentarium in management, it is imminent to identify robust prognosis biomarkers. This project will set forth the first collaboration between the Michigan Medicine Department of Dermatology and the PKUHSC Department of Dermatology, as well as Venereology from the Peking University First Hospital, drawing on the unique resources and the expertise of the investigators from the two institutions. First, we have a large Chinese CTCL cohort in PKUHSC with records and/or samples from >600 patients. Second, UMHS and the Dermatology clinics have access to >1,400 CTCL patients’ medical records, and we also banked the biopsies with various immunophenotypes of these patients. Thirdly, we have vast experience in statistical and omics analysis for assessing disease outcomes, including in-house bioinformatics pipelines developed in the Michigan Medicine Center for Cutaneous Bioinformatics.