<unk>  replacing a lymph node; the bubble-like outgrowths are enlarged follicles. The diagnosis of<unk>  depends on examining involved tissues for histological, immunological, and chromosomal abnormalities that are indicative of the disease.<unk>  usually involves enlarged lymph nodes populated by abnormal follicles (see adjacent picture) that when examined histologically contain a mixture of centrocytes or centroblast surrounded by non-malignant cells, mostly T-cells. The centrocytes, which typically outnumber centroblasts, are small to medium-sized B-cell lymphocytes that characteristically exhibit cleaved nuclei; the centropblasts are larger B-cell lymphocytes without cleaved nuclei. Rare cases of<unk>  may show lesions that contain tissue infiltrations dominated by B-cells with features of precursor (i.e. "blast") cells, monocytes, or malignant mantle cells such as those found in mantle cell lymphoma. Immunochemical analyses reveal that these cells generally express B-cell surface markers including the CD10 (60% of cases), CD20, CD19, CD22, and CD79 but not CD5, CD11c, or CD23 cell surface proteins; genomic analyses reveal that these cells contain t(14:18)(q32:q21.3) translocation (85-90% of cases), 1p36 deletions (60-70% of cases), and with far less frequency the other genomic abnormalities listed in the above sections on Pathophysiology and Presentation and course. None of these protein markers or genomic abnormalities are diagnostic for<unk> , e.g. the t(14:18)(q32:q21.3) translocation is found in 30% of diffuse large B-cell lymphoma and in a small number of reactive benign lymph nodes. Rather, the diagnosis is made by a combination of histological, immunological, and genomic abnormalities. According to World Health Organization (WHO) criteria, differences in the microscopically-determined morphology of these tissues can be used to diagnose and categorized<unk>  into the following 3 Grades with grade 3 having A and B subtypes: Histologic comparison of cell types in a germinal center, H&E stain:- Centrocytes are small to medium size with angulated, elongated, cleaved, or twisted nuclei.- Centroblasts are larger cells containing vesicular nuclei with one to three basophilic nucleoli apposing the nuclear membrane.-<unk>  dendritic cells have round nuclei, centrally located nucleoli, bland and dispersed chromatin, and<unk> attening of adjacent nuclear membrane. *Grade 1: follicles have 15 centroblasts per hpf. *Grade 3A: Grade 3 in which the follicles contain predominantly centrocytes. *Grade 3B: Grade 3 in which the follicles consist almost entirely of centroblasts. Grades 1 and 2 are regarded as low grade<unk> ; Grade 3A is usually also regarded as low grade<unk>  although some studies have regarded it as high grade<unk> ; and Grade 3B is regarded as a highly aggressive<unk>  in the t-FL category. In addition to grade 3B disease, histologic examinations may reveal other evidence of t-FL such as histologic findings consistent with<unk>  and diffuse large cell lymphoma in the same tissue (referred to as composite lymphomas) or in separate tissues (referred to as (discordant lymphomas) or histologic findings similar to those found in Burkitt lymphoma, precursor B-cell lymphoblastic leukemia, plasmablastic lymphoma, the high grade subtype of B-cell lymphoma, Hodgkin lymphoma of the B-cell type, chronic lymphocytic leukemia/small cell lymphocytic lymphoma, or histiocytic sarcoma. Other findings indicating the presence of this transformation include rapid growth in size of lymph nodes, recently acquired or new B symptoms, recent development of<unk>  lesions in non-nodal tissue, rapid rises in serum lactate dehydrogenase levels, and the presence of high levels of serum calcium. Differential diagnosis<unk>  may be confused with marginal zone B-cell lymphoma, mantle cell lymphoma, and the small lymphocytic lymphoma variant of chronic lymphocytic leukemia. The malignant cells in marginal zone B-cell lymphoma may form<unk>  structures but commonly proliferate in the marginal zone rather than germinal center of lymphoid tissues. These malignant cells often show features of monocytes or plasma cells. Mantle cell lymphomas show monotonous, medium-sized lymphocytes, monocytes, and atrophied germinal centers; unlike<unk> , the malignant lymphocytes in this disease are positive for Cyclin D1 by immunohistochemistry staining. Small lymphocytic lymphomas are composed of nodular structures with small- to medium-sized malignant cells surrounding immature lymphocytes and immunoblasts. The malignant cells in this disease, unlike<unk> , stain positive for CD5 and CD23.
Follicular lymphoma
Indolent lymphoma
Gray zone lymphoma
Marginal zone B-cell lymphoma
Thymic carcinoma
Aggressive lymphoma
Nodal marginal zone B cell lymphoma
Mixed-cell lymphoma