title: Epidermotropic secondary cutaneous involvement by relapsed angioimmunoblastic T-cell lymphoma mimicking mycosis fungoides: a case report.
abstract: Angioimmunoblastic T-cell lymphoma (AITL) is frequently associated with skin lesions, but epidermotropic cutaneous involvement has never been described. A 37-year-old man presented with erythematous and pruriginous plaques, clinically suggestive of mycosis fungoides, distributed all over the body, 3 weeks after the last line of a polychemotherapy, given for an AITL diagnosed 1 year earlier on a lymph node biopsy. Skin biopsy showed an epidermotropic CD4(+)  T-cell lymphoma, so that a diagnosis of mycosis fungoides was first proposed. Further investigations showed that atypical lymphocytes strongly expressed CD10 and markers of follicular helper T cells (T(FH) ) including PD1, BCL-6 and CXCL13. The diagnosis of an unusual epidermotropic cutaneous localization of the AITL was finally made, supported by the presence of the same T-cell clone in the initial lymph node biopsy and the skin. We therefore recommend performing markers of T(FH)  cells in patients with unusual epidermotropic cutaneous T-cell lymphomas, particularly if they have any clinical features suggestive of AITL.
authors.affiliation: Department of Pathology, Hospital General San Juan de Dios, Guatemala City, Guatemala.
authors.forename: Ana
authors.initials: A
authors.lastname: Ponciano
authors.forename: Anne
authors.initials: A
authors.lastname: de Muret
authors.forename: Laurent
authors.initials: L
authors.lastname: Machet
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Gyan
authors.forename: Christophe
authors.initials: C
authors.lastname: Monegier du Sorbier
authors.forename: Valérie
authors.initials: V
authors.lastname: Molinier-Frenkel
authors.forename: Philippe
authors.initials: P
authors.lastname: Gaulard
authors.forename: Nicolas
authors.initials: N
authors.lastname: Ortonne
mesh_terms: D000328:Adult; D014408:Biomarkers, Tumor / Q000378:metabolism; D002999:Clone Cells; D003937:Diagnosis, Differential; D006801:Humans; D007119:Immunoblastic Lymphadenopathy / Q000175:diagnosis* / Q000378:metabolism; D008198:Lymph Nodes / Q000473:pathology; D016411:Lymphoma, T-Cell, Peripheral / Q000175:diagnosis* / Q000378:metabolism; D008297:Male; D009182:Mycosis Fungoides / Q000175:diagnosis*; D015260:Neprilysin / Q000378:metabolism; D012008:Recurrence; D012867:Skin / Q000378:metabolism / Q000473:pathology*; D012878:Skin Neoplasms / Q000175:diagnosis* / Q000378:metabolism; D006377:T-Lymphocytes, Helper-Inducer / Q000378:metabolism / Q000473:pathology
chemical_list: D014408:Biomarkers, Tumor; D015260:Neprilysin