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Diffuse large B-cell lymphoma (DLBCL or DLBL) is a cancer of B cells, a type of white blood cell responsible for producing antibodies. It is the most common type of non-Hodgkin lymphoma among adults,〔 with an annual incidence of 7–8 cases per 100,000 people per year.〔〔 This cancer occurs primarily in older individuals, with a median age of diagnosis at approximately 70 years of age,〔 though it can also occur in children and young adults in rare cases.〔 DLBCL is an aggressive tumor which can arise in virtually any part of the body,〔 and the first sign of this illness is typically the observation of a rapidly growing mass, sometimes associated with fever, weight loss, and night sweats.〔 The causes of diffuse large B-cell lymphoma are not well understood. Usually DLBCL arises from normal B cells, but it can also represent a malignant transformation of other types of lymphoma or leukemia. An underlying immunodeficiency is a significant risk factor. Infection with Epstein–Barr virus has also been found to contribute to the development of some subgroups of DLBCL. Diagnosis of DLBCL is made by removing a portion of the tumor through a biopsy, and then examining this tissue using a microscope. Usually a hematopathologist makes this diagnosis.Several subtypes of DLBCL have been identified, each having a different clinical presentation and prognosis. However, the usual treatment for each of these is chemotherapy, often in combination with an antibody targeted at the tumor cells.Through these treatments, more than half of patients with DLBCL can be cured,〔 and the overall five-year survival rate for older adults is around 58%.〔 ==Classification== Diffuse large B-cell lymphoma encompasses a biologically and clinically diverse set of diseases,〔 many of which cannot be separated from one another by well-defined and widely accepted criteria. The World Health Organization (WHO) classification system defines more than a dozen subtypes, each of which can be differentiated based on the location of the tumor, the presence of other cells within the tumor (such as T cells), and whether the patient has certain other illnesses related to DLBCL. One of these well-defined groupings of particular note is "Primary mediastinal (thymic) large B cell lymphoma", which arises within the thymus or mediastinal lymph nodes. In some cases, a tumor may share many features with both DLBCL and Burkitt's lymphoma. In these situations, the tumor is classified as simply “B-cell lymphoma, unclassifiable, with features intermediate between diffuse large B-cell lymphoma and Burkitt lymphoma”. A similar situation can arise between DLBCL and Hodgkin's lymphoma; the tumor is then classified as “B-cell lymphoma, unclassifiable, with features intermediate between diffuse large B-cell lymphoma and Hodgkin’s lymphoma”. When a case of DLBCL does not conform to any of the well-defined subtypes, and is also not considered unclassifiable, then it is classified as “diffuse large B-cell lymphoma, not otherwise specified” (DLBCL, NOS). The majority of DLBCL cases fall into this category. Much research has been devoted to separating this still-heterogeneous group; such distinctions are usually made along lines of cellular morphology, gene expression, and immunohistochemical properties. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Diffuse large B-cell lymphoma」の詳細全文を読む スポンサード リンク
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