title: A cyclin D1-positive diffuse large B-cell lymphoma of germinal center B-cell-like subtype in the right tonsil: A rare case report.
abstract: BACKGROUND
  Cyclin D1-positive tumor cells are commonly found in mantle cell lymphoma but they are very rare in diffuse large B-cell lymphoma.
  
  
  RESULTS
  Here we present a rare case of cyclin D1-positive diffuse large B-cell lymphoma in the right tonsil of a 50-year-old man. Computed tomographic imaging detected a mass, about 2.5 cm × 1.8 cm in size, in the left side of the oropharynx.
  
  
  METHODS
  Microscopically, the tumor cells were located under the pharyngeal mucosa and diffusely arranged. The tumor cells were large, with marked nuclear atypia. On performing immunohistochemistry, the tumor cells showed diffuse positive staining for CD10, CD20, cyclin D1, and Pax-5, and negative staining for CD3, CD15, CD30, CD56, and CK. Bcl-6 and Mum-1 expression were observed in 60% and 80% of tumor cells, respectively. The tumor Ki67 index was about 60%. Based on these findings, The tumor was diagnosed as a rare cyclin D1-positive diffuse large B-cell lymphoma rather than a mantle cell lymphoma.
  
  
  CONCLUSIONS
  Cyclin D1-positive large B-cell lymphoma is rare, but as large B-cell lymphoma is a common type of lymphoma, cyclin D1-positive large B-cell lymphoma should be considered a major possibility during differential diagnosis, including in the tonsils.
authors.affiliation: Department of Pathology, First Affiliated Hospital and College of Basic Medical Sciences, China Medical University, Shenyang, China.
authors.forename: Changrui
authors.initials: C
authors.lastname: Jiang
authors.forename: Xiuying
authors.initials: X
authors.lastname: Shi
authors.forename: Chuifeng
authors.initials: C
authors.lastname: Fan
mesh_terms: D059248:Chemoradiotherapy; D019938:Cyclin D1 / Q000276:immunology; D018858:Germinal Center; D006801:Humans; D016403:Lymphoma, Large B-Cell, Diffuse / Q000000981:diagnostic imaging / Q000473:pathology* / Q000628:therapy; D008297:Male; D008875:Middle Aged; D051757:PAX5 Transcription Factor / Q000276:immunology; D014066:Palatine Tonsil / Q000000981:diagnostic imaging / Q000473:pathology*; D014057:Tomography, X-Ray Computed
chemical_list: C530104:CCND1 protein, human; D051757:PAX5 Transcription Factor; C497281:PAX5 protein, human; D019938:Cyclin D1