Stage‐related increase in PIM2 expression in mycosis fungoides

The oncogene PIM2 is upregulated in several malignancies but has never been investigated in mycosis fungoides (MF), the most common type of cutaneous T‐cell lymphoma (CTCL). PIM2 is a well‐known oncogene and is regulated by cell signaling pathways like the JAK/STAT‐ and NF‐kB‐pathway, key regulators in the pathogenesis of CTCL. The aim of this study was to examine the role of PIM2 in MF. PIM2 gene expression was measured in 81 formalin‐fixed paraffin‐embedded skin biopsies from patients with MF and 46 control biopsies from healthy skin (HS) and benign inflammatory skin disease (BID). Validation of PIM2 protein expression was performed on selected biopsies with immunohistochemical staining. We found a significant difference in gene expression levels between both early stage MF and HS ( p < 0.0001), and BID ( p < 0.0001). In addition, the PIM2 gene expression was higher in advanced‐stage MF compared to early stage disease ( p = 0.0001). No significant difference in gene expression levels was found between patients with and without disease progression. In conclusion, we found PIM2 expression is significantly increased in MF compared to controls, and in advanced‐stage MF compared to early stage MF. These findings could potentially have diagnostic value in discriminating early stage MF from BID.