The role of macrophages in the pathogenesis of mycosis fungoides

Summary Background Macrophages are classified into classically activated (M1) and alternatively activated (M2) macrophages. Decrease in macrophage number in tumour tissue with treatment has been reported. Aim The aim of this study was to determine whether treatment has an effect on the number of dermal M1 and M2 macrophages in patients with mycosis fungoides (MF). Methods In total, 21 patients (8 women, 13 men; age range 42–73 years) were included in this study. We determined markers for dermal M1 (inducible nitric oxide synthase and CD68) and M2 (markers: CD163 and CD206) macrophages using double immunohistochemistry to reduce the error rate, and then counted the cells. Results The number of dermal M1 cells was significantly lower pretreatment compared with post‐treatment (P < 0.01). The numbers of dermal M2 cells were also numerically decreased by treatment. These results did not change significantly after exclusion of the patients who had recurrence (n = 2). There were no statistically significant differences between groups classified by stage, lesion type or treatment outcome. Conclusion Macrophage numbers are decreased in MF after treatment of tumour tissue.