title: Revising the historical collection of epithelioid cell-rich lymphomas of the Kiel Lymph Node Registry: what is Lennert's lymphoma nowadays?
abstract: OBJECTIVE
  Lennert's lymphoma is a rare variant of peripheral T-cell lymphoma (PTCL) not otherwise specified (NOS). The aim of this study was to further characterize this tumour.
  
  
  RESULTS
  Historical material of 97 lymphomas with a high content of epithelioid cells, collected at the Kiel Lymph Node Registry were reviewed, by applying immunohistochemistry and current diagnostic criteria. Among all cases revised, various B-cell lymphoma entities (25 cases), Hodgkin lymphomas (21 cases) and PTCL subtypes (48 cases) could be identified. A distinctive subgroup of eight PTCLs was found that were regarded as genuine Lennert's lymphomas. These cases were characterized by mild atypia, a non-activated cytotoxic phenotype [TIA1 cytotoxic granule-associated RNA binding protein (TIA1)-positive(+) and granzyme B-negative], and a substantial lack of follicular T-helper (T(FH) ) cell markers. Among the other PTCLs, including angioimmunoblastic T-cell lymphoma and PTCL NOS, many cases with positivity for more than three T(FH) cell-associated molecules were recorded.
  
  
  CONCLUSIONS
  Our study shows that, according to current criteria, Lennert's lymphoma is a rare but distinctive entity among epithelioid cell-rich lymphomas, differing on grounds of morphology and immunophenotype from other PTCL subtypes. An additional finding is the broad morphological spectrum of epithelioid-cell rich PTCLs showing a T(FH) cell phenotype.
authors.affiliation: Senckenberg Institute of Pathology, Goethe University, Frankfurt am Main, Germany. s.hartmann@em.uni-frankfurt.de
authors.forename: Sylvia
authors.initials: S
authors.lastname: Hartmann
authors.forename: Claudio
authors.initials: C
authors.lastname: Agostinelli
authors.forename: Wolfram
authors.initials: W
authors.lastname: Klapper
authors.forename: Penelope
authors.initials: P
authors.lastname: Korkolopoulou
authors.forename: Karoline
authors.initials: K
authors.lastname: Koch
authors.forename: Teresa
authors.initials: T
authors.lastname: Marafioti
authors.forename: Pier Paolo
authors.initials: PP
authors.lastname: Piccaluga
authors.forename: Efstratios
authors.initials: E
authors.lastname: Patsouris
authors.forename: Stefano
authors.initials: S
authors.lastname: Pileri
authors.forename: Martin-Leo
authors.initials: ML
authors.lastname: Hansmann
mesh_terms: D049673:History, 20th Century; D006801:Humans; D007150:Immunohistochemistry; D016399:Lymphoma, T-Cell / Q000266:history* / Q000473:pathology*; D012042:Registries