The heterogeneity of follicular lymphomas: from early development to transformation.
Follicular lymphoma (FL) is a lymphoma composed of germinal center B cells, i.e., centroblasts and centrocytes, that almost always show at least a focal follicular growth pattern. Most cases have a characteristic CD5-, CD10+, BCL6+, and BCL2+ immunophenotype, and 85 % of cases exhibit the hallmark translocation t(14;18)(q32;q21) involving BCL2 and IGH. Although the typical clinicopathological findings of FL are well recognized, cases with unusual clinical, morphologic, immunophenotypic, and genetic features may pose problems in diagnosis and nomenclature. In the slide workshop organized by the European Association for Haematopathology (EAHP) and the Society for Hematopathology (SH) held in Istanbul, Turkey, unusual variants of FL were discussed based on the submitted cases, including early lesions, localized extranodal presentation, uncommon immunophenotype, rare genetic alterations, diffuse variant, and marginal zone differentiation. Interesting features such as blastoid morphology and unusual progression forms were presented, aiming to understand the genetic basis of transformation. In this report, novel findings and diagnostic challenges emerging from the submitted cases will be highlighted, and new terminologies for some of these lesions are proposed.
Department of Bio-Pathology, Institut Paoli-Calmettes, Aix-Marseille University, Marseille, France. xerril@ipc.unicancer.fr.
Luc
L
Xerri
Institute of Pathology, University Hospital Basel, Basel, Switzerland.
Stephan
S
Dirnhofer
Institute of Pathology and Neuropathology, Eberhard Karls University of Tübingen and Comprehensive Cancer Center, University Hospital Tübingen, Tübingen, Germany.
Leticia
L
Quintanilla-Martinez
Department of Laboratory Medicine, Division of Pathology, Karolinska Institutet and Karolinska University Hospital Huddinge, Stockholm, Sweden.
Birgitta
B
Sander
Queen Elizabeth Hospital, Hong Kong, SAR, China.
John K C
JK
Chan
Hospital Clinic, University of Barcelona, Barcelona, Spain.
Elias
E
Campo
Division of Hematopathology, Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
Steven H
SH
Swerdlow
Department of Clinical Pathology, Robert-Bosch-Hospital and Dr. Margarete Fischer-Bosch Institute of Clinical Pharmacology, Stuttgart, Germany.
German
G
Ott
D000818:Animals; D001402:B-Lymphocytes / Q000473:pathology*; D014408:Biomarkers, Tumor / Q000032:analysis* / Q000235:genetics; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D016130:Immunophenotyping / Q000379:methods; D008224:Lymphoma, Follicular / Q000175:diagnosis / Q000235:genetics / Q000473:pathology*; D014178:Translocation, Genetic / Q000235:genetics
D014408:Biomarkers, Tumor
BCL2; Classification; Cytogenetics; Follicular lymphoma; Immunohistochemistry