title: Incidental MALT type lymphoma exhibiting prominent plasma cell differentiation associated with Hashimoto's thyroiditis. A two case report.
abstract: We present here two cases of incidental extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) showing prominent plasma cell differentiation associated with Hashimoto's thyroiditis (HT). Histological examination demonstrated that both lesions exhibited HT including lymphoplasmacytic infiltration with the formation of germinal centers, destruction of the normal thyroid follicular architecture, Hürthle cell changes, and squamous metaplasia. The dominant tumor nodules of both cases contained large, well-circumscribed but unencapsulated aggregation of mature plasma cells and scattered centrocyte-like cells (CCL-cells). Both lesions contained a few lymphoepithelial lesions. Moreover, immunohistochemical study demonstrated that plasma cells and CCL-cells of these two lesions contained monotypic intracytoplasmic kappa light chain. Other small B-cell lymphomas, plasmacytoma and plasmablastic lymphoma were excluded using stains for CD5, CD10, CD23, CD43, CD56. Cyclin D1, human herpes virus type-8.
authors.affiliation: Department of Pathology and Clinical Laboratories, Gunma Cancer Center Hospital, 617-1, Takabayashinishi-cho, Ohta, 373-8550, Japan. mkojima@gunma-cc.jp
authors.forename: Masaru
authors.initials: M
authors.lastname: Kojima
authors.forename: Ken
authors.initials: K
authors.lastname: Shimizu
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Shimizu
authors.forename: Nobuhide
authors.initials: N
authors.lastname: Masawa
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000032:analysis; D002454:Cell Differentiation; D005260:Female; D050031:Hashimoto Disease / Q000150:complications* / Q000473:pathology*; D006801:Humans; D007150:Immunohistochemistry; D033162:Incidental Findings; D018442:Lymphoma, B-Cell, Marginal Zone / Q000150:complications* / Q000473:pathology*; D008297:Male; D010950:Plasma Cells / Q000473:pathology*
chemical_list: D014408:Biomarkers, Tumor