Primary central nervous system lymphoma (PCNSL) is an extranodal form of non-Hodgkins lymphoma (NHL) occurring in the craniospinal axis that accounts for 13% of all central nervous system malignancies. The majority of PCNSLs are high-grade B-cell lymphomas that differ from systemic B-cell NHLs in their less favorable prognosis. PCNSL appears to be increasing in incidence, reaching its peak in the fifth to seventh decades of life in immunocompetent patients. This book aims to provide up-to-date knowledge on the biology, diagnosis and treatment strategies associated with PCNSL. Separate chapters are specifically devoted to the biology, pathology, diagnosis, radiation therapy, chemotherapy regimens, emerging new agents, specific subtypes, and outcome associated with PCNSL. The authors are scientists and practicing physicians at university hospitals in Japan and South Korea. The book is written for postgraduate students, residents, basic scientists and physicians, as well as all medical professionals. The material covered in this book will serve as a foundation for the readers to keep up with current and future developments in this specific field of research and clinical practice.