title: Mucosa-associated lymphoid tissue of the thymus hyperplasia vs lymphoma.
abstract: In the thymus, the relationship between lymphofollicular hyperplasia and mucosa-associated lymphoid tissue (MALT)-type lymphoma is uncertain. We analyzed 14 cases with a diagnosis of thymic follicular hyperplasia in patients with connective tissue disease (n = 2), myasthenia gravis (n = 11), or both (n = 1). In 11 cases, well-defined reactive lymphoid follicles were surrounded by a continuous layer of medullary epithelial cells. A polyclonal rearrangement of the immunoglobulin heavy chain gene (IgH) was observed. In 3 cases, ill-defined lymphoid follicles with sheets of centrocytic-like B cells disrupting the medullary cytokeratin epithelial network were observed on certain sections. These cells expressed the phenotypic features of memory B cells with CD20, CD79a, and bcl-2 positivity and CD5, CD10, CD23, and bcl-6 negativity, and a monoclonal rearrangement of the IgH gene was detected. Appropriate sampling, cytokeratin staining, and molecular analyses may help to identify early MALT-type lymphoma developing in the setting of thymic lymphofollicular hyperplasia.
authors.affiliation: Department of Pathology and Molecular Biology, University of Bordeaux 2, Pessac, France.
authors.forename: Marie
authors.initials: M
authors.lastname: Parrens
authors.forename: Pierre
authors.initials: P
authors.lastname: Dubus
authors.forename: Marie
authors.initials: M
authors.lastname: Danjoux
authors.forename: Jacques
authors.initials: J
authors.lastname: Jougon
authors.forename: Pierre
authors.initials: P
authors.lastname: Brousset
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Velly
authors.forename: Antoine
authors.initials: A
authors.lastname: de Mascarel
authors.forename: Jean P
authors.initials: JP
authors.lastname: Merlio
mesh_terms: D000328:Adult; D015703:Antigens, CD / Q000276:immunology; D003937:Diagnosis, Differential; D005260:Female; D015322:Gene Rearrangement, B-Lymphocyte; D006801:Humans; D007143:Immunoglobulin Heavy Chains / Q000235:genetics; D018442:Lymphoma, B-Cell, Marginal Zone / Q000235:genetics / Q000276:immunology / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009092:Mucous Membrane / Q000473:pathology; D013950:Thymus Gland / Q000473:pathology*; D013952:Thymus Hyperplasia / Q000235:genetics / Q000276:immunology / Q000473:pathology*
chemical_list: D015703:Antigens, CD; D007143:Immunoglobulin Heavy Chains