Pia Rude Nielsen, Jens Ole Eriksen, Mia Dahl Sørensen, Ulrike Wehkamp, Lise M. Lindahl, Michael Bzorek, Lars Iversen, Anders Woetman, Niels Ødum, Thomas Litman, Lise Mette Rahbek Gjerdrum
DOI: 10.2340/00015555-3775

Mycosis fungoides is the most common type of cutaneous T-cell lymphoma. The inflammatory micro­environment in mycosis fungoides is complex. There is accumulating evidence that the neoplastic T-cells take control of the microenvironment and thereby promote their own expansion by suppressing cellular immunity. B-cells have proved to be upregulated in large-cell transformed mycosis fungoides, and could potentially play a role in disease progression. To investigate the presence of B-cells in mycosis fungoides compared with controls, this study analysed 85 formalin-fixed and paraffin-embedded mycosis fungoides biopsies. MS4A1 gene expression was significantly upregulated in mycosis fungoides compared with controls (p < 0.0001) and further upregulated in disease progression, (p = 0.001). Digital quantification of PAX5+/CD20+ cells confirmed the increased presence of B-cells in mycosis fungoides compared with controls. No co-labelling of CD3/CD20 was observed in the neoplastic T-cells. This study found a significantly increased presence of B-cells in the tumour-associated microenvironment in mycosis fungoides. These findings could potentially lead to new treatment strategies for mycosis fungoides.

The inflammatory microenvironment in mycosis fungoides is complex, and little is known about the presence of B-cells in this disease. This retrospective study examined 85 biopsies from patients with all stages of mycosis fungoides. MS4A1 gene expression was significantly upregulated in mycosis fungoides compared with controls, and further upregulated in disease progression. Digital quantification of double (PAX5/CD20)-stained slides confirmed the increased presence of B-cells in mycosis fungoides compared with controls. No aberrant CD20 expression was found in the neoplastic T cells. These findings could potentially promote new treatment strategies for mycosis fungoides.