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.

Primary cutaneous follicular helper T‐cell lymphoma: diagnostic pitfalls of this new lymphoma subtype

“…PTCL-NOS or angioimmunoblastic T-cell lymphoma (AITL). 8 Of note, systemic involvement has not been showed in any of the reported patients with CT FH CL. As nodal T FH lymphomas also express PD-1, ICOS, CXCL13 and potentially CD10 and bcl6, 3 a complete staging must be performed in any case of cutaneous lymphoma manifestations to exclude cutaneous spread of systemic lymphoma.…”

“…Important differential diagnoses in cases with or without epidermotropic T‐helper cell phenotype are secondary cutaneous manifestations of nodal peripheral T‐cell lymphomas, e.g. PTCL‐NOS or angioimmunoblastic T‐cell lymphoma (AITL) . Of note, systemic involvement has not been showed in any of the reported patients with CT FH CL.…”

Primary cutaneous follicular helper T‐cell lymphoma

“…Both follicular dendritic cell hyperplasia and the presence of high endothelial venules are highly characteristic of lymph node specimens infiltrated by AITL . Nevertheless, none of the authors have reported expansion of follicular dendritic cells meshwork on skin specimens infiltrated by AITL . Moreover, capillary hyperplasia is not always present on skin specimens and its presence lacks diagnostic specificity because it could be found in many other conditions .…”

“…Within the large group of PTCL‐NOS, it is also recognized, that a subset has TFH‐like features, in the form of its specific molecular profile, a similar genetic signature and/or show overlapping pathologic features . The frequency of skin involvement in the setting of AITL varies according to the series, ranging from 2 to 50% of the patients . The histopathologic spectrum of secondary cutaneous involvement by AITL is very broad.…”

Extranodal Marginal Zone Lymphoma–like Presentations of Angioimmunoblastic T-Cell Lymphoma

“…Clonal populations of T-cells are seen in 87% of cases and clonal B-cells can be found in up to 40–80% of cases (with only 5 cases tested from previous reports) 10,39 . Uncommon histologic presentations include granulomatous dermatitides 4,40 , an atypical linear IgA dermatosis form 40 , prurigo-like eruptions 41 , and rarely an epidermotropic form mimicking mycosis fungoides (MF) 42 .…”