Histological examination of the lesions in DFL usually reveals them to be localized to the GI tract mucosa and submucosa. The lesions consist of abnormal germinal center-containing lymphoid follicles overcrowded with a uniformly-sized population of malignant centrocytes and rare centroblasts. The lesions are classified as low grade (i.e. Lugano classification Grades 1 or 2) in 95-100% of cases. Immunochemical analyses indicate that the latter cells express CD20, CD10, BCL6, and CD79A and have a very low proliferation rate as defined by the intensity of their expression of Ki-67. They also overexpress Bcl2 as a consequence of having the t(14:18)q32:q21) translocation. These findings are similar to those in<unk>  lymphoma but the malignant cells in DFL generally have fewer genomic abnormalities than those in<unk>  lymphoma and the profile of overexpressed genes in DFL tissues more closely resemble those in marginal zone than<unk>  lymphoma tissues. The diagnosis of DFL depends on finding: the cited histological, and immunolochemical abnormalities; the t(14:18)q32:q21) translocation; and no evidence that the disease ranges outside of the GI tract as evidenced by negative results for, e.g. bone marrow biopsy and CT scan of the abdomen which thereby rule out involvement of the bone marrow and mesenteric as well as other abdominal lymph node, respectively. Differential diagnoses<unk>  lymphoma differs from DFL by having: lesions which commonly lie outside of the GI tract sites outlined in the Presentation section; a histology more often categorized as Grade 3; and malignant cells that express activation-induced cytidine deaminase but not CD27, CCL20, MAdCAM-1, or C-C chemokine receptor<unk>  6. MALT lymphoma differs from DFL by having: lesions which commonly lie in the stomach and other tissues outside of the GI tract sites outlined in the Presentation section (except for a special subtype of malt lymphoma termed immunoproliferative small intestinal disease that is endemic to the Middle East); involvement of malignant B-cells that do not express CD5, CD10, or BCL6 and commonly have a translocation between chromosomes 18 and 11, i.e. t(11:18) but not the t(14:18)q32:q21) translocation; and associations with chronic inflammatory diseases and chronic antigen stimulation; Mantle cell lymphoma differs from DFL by having: only occasional involvement of the GI tract with polyps that on histologic examination may involve the lamina propria and often infiltrate between rather that replacing intestinal glands and malignant cells which commonly express cyclin D1 and a translocation between chromosomes 11 and 14, i.e. t(11:14) but not the t(14:18)q32:q21). translocation.
Duodenal-type follicular lymphoma
MALT lymphoma
Monomorphic epitheliotropic intestinal T cell lymphoma
Pediatric-type follicular lymphoma
Splenic marginal zone lymphoma
Nodular lymphocyte predominant Hodgkin lymphoma
Nodal marginal zone B cell lymphoma
Indolent lymphoma