Peripheral T cell lymphomas with follicular T helper phenotype: a new basket or a distinct entity? Revising Karl Lennert's personal archive.
OBJECTIVE
To revise 25 cases selected from Karl Lennert's personal archive (21) and Bologna and Frankfurt Registries (four) because of cytological similarities.


RESULTS
All cases were provided with paraffin blocks and studied by immunohistochemistry and molecular techniques. While phenotyping was very informative, among molecular studies only EBER in situ-hybridization (ISH) was successful. Twenty-two cases were concluded as peripheral T cell lymphomas (PTCL). Of these, six were reclassified as angioimmunoblastic T cell lymphoma (AITL), 13 as PTCL, not otherwise specified (NOS), including four follicular variants and one tumour with T-zone pattern, and three as borderline tumours between AITL and PTCL/NOS. All these cases consisted homogeneously of small/medium-sized elements with mild nuclear atypia and an evident rim of clear/pale cytoplasm. On immunohistochemistry, they regularly expressed three to six follicular helper T cell (FTH)-associated markers. EBER-ISH revealed scattered EBV-infected B cells in all tumours except those with 'follicular' growth pattern. The content of follicular dendritic cells and high-endothelial venules varied significantly depending on the histotype.


CONCLUSIONS
This study shows that: (i) historical material can be still employed usefully, and (ii) the FTH-phenotype corresponds to a broad spectrum of PTCLs that might form a new category to be validated in future molecular and clinicopathological analyses.
Haematopathology Section, Department of Haematology and Oncology 'L. and A. Seràgnoli', S. Orsola-Malpighi Hospital, University of Bologna, Italy.
Claudio
C
Agostinelli
Sylvia
S
Hartmann
Wolfram
W
Klapper
Penelope
P
Korkolopoulou
Simona
S
Righi
Teresa
T
Marafioti
Pier Paolo
PP
Piccaluga
Efstratios
E
Patsouris
Martin-Leo
ML
Hansmann
Karl
K
Lennert
Stefano A
SA
Pileri
D001402:B-Lymphocytes / Q000473:pathology / Q000821:virology; D020031:Epstein-Barr Virus Infections / Q000150:complications / Q000266:history / Q000473:pathology; D049673:History, 20th Century; D006801:Humans; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D008224:Lymphoma, Follicular / Q000266:history / Q000473:pathology* / Q000821:virology; D016411:Lymphoma, T-Cell, Peripheral / Q000266:history / Q000473:pathology* / Q000821:virology; D010641:Phenotype; D012367:RNA, Viral / Q000032:analysis; D012042:Registries; D006377:T-Lymphocytes, Helper-Inducer / Q000473:pathology*; D014015:Tissue Banks / Q000266:history
D012367:RNA, Viral