title: Localized lymphoid hyperplasia of the rectum representing progressive transformation of the germinal center. A report of two cases.
abstract: Histologically, benign lymphoid hyperplasia (BLH) of the rectum is usually characterized by large lymphoid follicles with active germinal centers, and a narrow surrounding mantle zone and marginal zone. We present two cases of BLH of the rectum demonstrating progressive transformation of the germinal center (PTGC). The patients were 50- and 71-year-old Japanese women. Colonoscopy demonstrated small sessile polyps in both cases. The resected specimen contained numerous lymphoid follicles with active germinal centers and a portion of the lymphoid follicles exhibited PTGC. The area showing PTGC contained a few large lymphoid cells resembling lymphocytic and histiocytic Reed-Sternberg cells of nodular lymphocyte-predominant Hodgkin lymphoma. These PTGC contained small- to-medium clusters of epithelioid cells in both cases. In situ hybridization studies demonstrated scattered Epstein-Barr virus (EBV)-encoded small RNA-positive medium and large lymphoid cells and crypt epithelium in both lesions. EBV may be involved in the etiology of a subset of BLH of the rectum. However, reactivity of lymphoid cells for EBV has been reported in lymphoid tissues in a high percentage of "normal" individuals. The etiology of BLH of the rectum remains unclear.
authors.affiliation: Department of Pathology and Clinical Laboratories, Gunma Cancer Center Hospital, Ohta, Japan. mkojima@gunma-cc.jp
authors.forename: Masaru
authors.initials: M
authors.lastname: Kojima
authors.forename: Misa
authors.initials: M
authors.lastname: Iijima
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Shimizu
authors.forename: Kazue
authors.initials: K
authors.lastname: Hoshi
mesh_terms: D000368:Aged; D002471:Cell Transformation, Neoplastic / Q000473:pathology*; D003937:Diagnosis, Differential; D020031:Epstein-Barr Virus Infections; D005260:Female; D018858:Germinal Center / Q000473:pathology* / Q000821:virology; D004854:Herpesvirus 4, Human; D006801:Humans; D006965:Hyperplasia; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D008221:Lymphoid Tissue / Q000473:pathology* / Q000821:virology; D008223:Lymphoma / Q000473:pathology; D008875:Middle Aged; D012007:Rectum / Q000276:immunology / Q000473:pathology*