A Case of Primary Cutaneous Natural Killer/T-Cell Lymphoma, Nasal Type, with Indolent Clinical Course: Monoclonal Expansion of Epstein-Barr Virus Genome Correlating with Terminal Aggressive Behavior

The document reports on a 39-year-old Japanese woman with primary cutaneous natural killer/T-cell lymphoma, nasal type (NKTL-NT), associated with Epstein-Barr virus (EBV). Initially presenting with subcutaneous nodules on her legs, she experienced an indolent disease course with multiple recurrences over 10 years, treated with radiotherapy. Later, a rapidly growing skin tumor on her abdominal wall was diagnosed as a more aggressive form of primary cutaneous NKTL-NT, leading to her death 8 months after. While early and late lesions were histopathologically and immunophenotypically similar, Southern blot analysis showed monoclonal expansion of the EBV genome in the late lesion, suggesting that genetic changes in an EBV-positive clone may have caused the disease to become more aggressive. The study concludes that the monoclonal expansion of the EBV genome is correlated with the aggressive terminal behavior of the lymphoma, and monitoring the clonality of the EBV genome could be important for prognosis in primary cutaneous NKTL-NT.