NK/T-cell lymphoma is associated with EBV in 90% to 100% of cases. This can be detected by in-situ hybridization for Epstein-Barr virus early RNA (EBER). The image shows strong nuclear labeling of most lymphoma cells. Image courtesy of: Genevieve Crane, MD, PhD, Johns Hopkins Hospital, Baltimore, Maryland, USA. The T-cell receptor (TCR) and immunoglobulin genes are not rearranged (i.e. germline in configuration) in the majority of cases. Mutations in p53 gene have been detected in 25% to 60% of cases. They correlate with large cell morphology and advanced clinical stage.