title: CD20 antigen may be expressed by reactive or lymphomatous cells of transformed mycosis fungoides: diagnostic and prognostic impact.
abstract: Mycosis fungoides (MF), the most common primitive cutaneous T-cell lymphoma, can undergo transformation in about 10% of cases. Transformed mycosis fungoides (T-MF) is often associated with the appearance of a CD20 component. The aim of this study was to analyze whether such cells are reactive or lymphomatous and to evaluate their prognostic impact. Among 311 T-MFs from the French Cutaneous Lymphoma Study Group registry, we studied 148 cases. CD20 was expressed in 88 cases (59%). The proportion of CD20 cells among T-MF lesions was <10% for 54 cases (38%), 10% to 49% for 71 cases (81%), and >50% for 17 cases (19%). We focused the study on 23 cases that contained >50% CD20 cells. To evaluate the nature of the CD20 component, we used immunohistochemistry (2 anti-CD20 antibodies, L26 and 7D1 clones, and 2 other anti-B-cell antigen antibodies, CD22 and PAX5) and a double-stain immunofluorescence technique (anti-CD20 and anti-CD3 antibodies). The clonality of B cells was studied by polymerase chain reaction. Three profiles were observed. In 15 of the 23 cases, the CD20 cells were reactive. In 6 cases, CD20 protein was aberrantly expressed in T-MF lesions. Lastly, there were 2 composite lymphomas (T-MF infiltrate with a B-cell follicular lymphoma). In view of this series, we propose a simple algorithm to help pathologists evaluate the nature of the CD20 component associated with T-MF. Although statistically not significant, there was a trend toward a worse prognosis in the presence of >50% CD20 cells and of a nodular perifollicular pattern of this component.
authors.affiliation: *Department of Pathology, the Tumor Bank and Tumor Biology Laboratory, the departments of Statistics and Dermatology, University Hospital of Bordeaux †Departments of Pathology and Dermatology, University Hospital of Paris-Est Créteil ‡Departments of Pathology and Dermatology, University Hospital of Montpellier §Departments of Pathology and Dermatology, University Hospital of Paris, APHP ∥Departments of Pathology and Dermatology, University Hospital of Tours ¶Departments of Pathology and Dermatology, University Hospital of Lyon #Departments of Pathology and Dermatology, University Hospital of Clermont-Ferrand, France.
authors.forename: Marie-Laure
authors.initials: ML
authors.lastname: Jullié
authors.forename: Martina
authors.initials: M
authors.lastname: Carlotti
authors.forename: Alexandre
authors.initials: A
authors.lastname: Vivot
authors.forename: Marie
authors.initials: M
authors.lastname: Beylot-Barry
authors.forename: Nicolas
authors.initials: N
authors.lastname: Ortonne
authors.forename: Eric
authors.initials: E
authors.lastname: Frouin
authors.forename: Agnes
authors.initials: A
authors.lastname: Carlotti
authors.forename: Anne
authors.initials: A
authors.lastname: de Muret
authors.forename: Brigitte
authors.initials: B
authors.lastname: Balme
authors.forename: Frédéric
authors.initials: F
authors.lastname: Franck
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Merlio
authors.forename: Béatrice
authors.initials: B
authors.lastname: Vergier
mesh_terms: D000465:Algorithms; D018951:Antigens, CD20 / Q000032:analysis / Q000096:biosynthesis*; D014408:Biomarkers, Tumor / Q000032:analysis*; D002471:Cell Transformation, Neoplastic / Q000473:pathology; D005455:Fluorescent Antibody Technique; D006801:Humans; D053208:Kaplan-Meier Estimate; D009182:Mycosis Fungoides / Q000175:diagnosis* / Q000378:metabolism / Q000401:mortality; D016133:Polymerase Chain Reaction; D011379:Prognosis; D012878:Skin Neoplasms / Q000175:diagnosis* / Q000378:metabolism / Q000401:mortality
chemical_list: D018951:Antigens, CD20; D014408:Biomarkers, Tumor