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Investigative Report

Stage-dependent Increase in Expression of miR-155 and Ki-67 and Number of Tumour-associated Inflammatory Cells in Folliculotropic Mycosis Fungoides

Lihi Atzmony, Lilach Moyal, Meora Feinmesser, Batya Gorovitz, Avraham Hirshberg, Iris Amitay-Laish, Hadas Prag-Naveh, Aviv Barzilai, Emmilia Hodak
DOI: 10.2340/00015555-3578

Preview of fully accepted paper, still not published in any volume

Abstract

Recent studies suggest that folliculotropic mycosis fungoides (FMF), the most common variant of mycosis fungoides (MF), presents with 2 distinct clinicopathological stages: early indolent stage and more aggressive advanced/tumour stage. To further characterize these stages, miR-155 expression was studied with qRT-PCR and found to be significantly higher in biopsies of tumour-stage FMF compared with early-stage FMF and inflammatory dermatoses. There was no statistically significant difference in miR-155 expression between early-stage FMF and early-stage MF, nor between tumour-stage FMF and tumour-stage MF. Immunohistochemical analysis revealed a significantly increased number of dermal Ki-67+ proliferating lymphocytes in tumour-stage FMF, together with an increased number of CD20+ B cells and CD68+ macrophages compared with early-stage FMF. Thus, similar to classic MF, miR-155, Ki-67 tumour cell immunoreactivity, and certain tumour-infiltrating inflammatory cells are differentially expressed in early- vs tumour-stage FMF. The results of this study corroborate the notion that FMF presents with 2 distinct stages.

Significance

Folliculotropic mycosis fungoides, the most common variant of mycosis fungoides, was recently suggested to present with 2 distinct stages: early-stage and advanced/tumour-stage, each with different prognostic implications. To gain further insight into the different presentations of folliculotropic mycosis fungoides, skin biopsies of folliculotropic mycosis fungoides were studied for miR-155 expression, a well-documented cancer promoter in classic mycosis fungoides, the proliferation marker Ki-67 expression, and the composition of the inflammatory infiltrate. This study shows that, similar to classic mycosis fungoides, expression of miR-155, dermal Ki-67 immunoreactivity, and the number of tumour-infiltrating B-cells and macrophages are also increased in a stage-dependent manner in folliculotropic mycosis fungoides.

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