Expression of CD31 in Mycosis Fungoides

Mycosis fungoides (MF) is the most common primary cutaneous T-cell lymphoma (CTCL) characterized by malignant proliferation of mature T lymphocytes and primary skin involvement. Recent reports suggest that angiogenesis may play a role in the growth and spread of this malignancy. Cluster of differentiation 31 (CD31) is a protein classified into the Ig-superfamily of cell adhesion molecules, expressed on endothelial cells and majority of hematopoietic non-erythroid cells. The aim of our study was to explore the role of angiogenesis in MF.

We evaluated the expression of CD31 in relation to clinicopathological data and potential impact on patients' outcome in MF utilizing immunohistochemistry (IHC) and western blot (WB) techniques in 73 and 19 MF and 21 and 4 control samples, respectively.

In the IHC study, statistical analysis revealed significantly higher CD31 expression in MF compared to the controls (p<0.0001) with highest expression in advanced stages vs. early ones and controls (p<0.0001 for both). In regard to skin involvement, expression was also elevated in more infiltrative (T3, tumors) and in more extensive (T4, erythroderma) cutaneous lesions compared to less infiltrative and limited skin lesions (T1, T2, patches and/or plaques) (p<0.01 for both). Regarding the extracutaneous spread, higher CD31 expression correlated with nodal involvement (N1-3 vs. N0; p<0.0001). In the WB study, statistical analysis revealed significantly higher CD31 expression only in advanced vs. early stage of MF (p<0.05). In regard to skin involvement, expression was also elevated in T3 and T4 as compared T1+T2 (p=0.08, p<0.05; respectively). Higher CD31 expression correlated with nodal involvement (N1-3 vs. N0; p<0.01). A strong significant correlation between CD31 expression at the protein level analyzed by IHC and WB was noticed (r=0.802, p<0.0001). Moreover, strong positive correlations between IHC expression of CD31 and podoplanin (PDPN; r=0.582, p<0.0001), vascular endothelial growth factor C (VEGFC; r=0.332, p<0.01) and Ki-67 (r=0.330, p<0.01) were disclosed.

Expression of CD31 in MF skin biopsies provides new evidence for the role of angiogenesis in the progression of MF. Additionally, the new data revealed prompts for further research on potential use of CD31 as a new marker of the disease advancement, as well as the target of new therapeutic strategies.