Division of Hematology-Oncology, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
Lymphoma is the most common hematologic malignancy, accounting for more than 40% of hematologic malignancies in Korea . However, lymphoma is not a single disorder but a heterogeneous group of subtypes that arise from abnormal B cells or T/NK cells at various stages of development. Although the diagnosis of lymphoma is mainly based on the pathologic findings of lymph node or bone marrow biopsy or both, the number of lymphoma subtypes is expected to increase with advances in molecular and cytogenetic techniques. Besides, the clinical manifestations related to extranodal involvement are also considered for the diagnosis of lymphoma because the involvement of particular extranodal sites can be reflected in the diagnosis of lymphomas. Furthermore, even if patients may have the same subtype of lymphoma, clinical features and treatment outcomes may be different depending on the site involved. Extranodal involvement of lymphomas can be classified as primary or secondary, based on whether the involvement of a certain extranodal organ is a predominant clinical presentation or not. For example, for a case presenting as a lymphoma involving stomach without additional pathologic lesions, it can be designated as primary gastric lymphoma. However, the occurrence of primary extranodal lymphoma is a relatively rare event, especially in those special organs including eyes, thyroid and adrenal glands.
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Therefore, multicenter collaborative study is definitely required for this kind of study focusing on rare subtypes of lymphomas or unusual lymphoma cases. The eight hospitals including Dong-A university hospital belongs to the Consortium for Improving Survival of Lymphoma (CISL). The CISL is a study group for prospective clinical trials for lymphoma patients and various retrospective analyses . Since the first meeting in February of 2006, the CISL performed more than 35 prospective clinical trials and comprised of 68 centers under the Korean Society of Hematology Lymphoma Working Party. In addition, the CISL reported many results of retrospective analyses like the article by Lee et al. in