This study is designed to collect tissue samples from the biopsy specimen that was used to diagnose hepatosplenic T-cell lymphoma (HSTCL), additional patient information, and if possible, to obtain additional samples including a single blood sample, a buccal swab sample and/or a bowel tissue sample. Samples obtained will be stored by the sponsor for future testing. In addition, demographic and clinical patient information will be collected. The study will be conducted in North America. Patients eligible for enrollment include males or females with IBD of any age who have a confirmed diagnosis of HSTCL. Patients will be identified through the sponsor's adverse event reporting systems. Cases reported to the sponsor's Medical Information Center will be queried to ascertain if the reporter is interested in participating in the study. Where appropriate, cases may also be identified through the sponsor's new or on-going clinical trials and registries. Samples may be collected from living patients or from stored tissue of deceased patients. This study will not restrict or introduce any therapeutic interventions, including medications. All patients will continue to be managed by their personal physicians. No healthy subjects will be enrolled in this study.