UVB
phototherapy is widely used for the treatment of
psoriasis and
atopic dermatitis, however, only limited reports evaluate its usefulness in the treatment of
mycosis fungoides. We introduced UVB
phototherapy to five patients with early-stage
mycosis fungoides. All of them were classified as stage IB (erythematous stage), and none had obtained a satisfactory response to other
therapies. After initial treatment with UVB
phototherapy, all the patients obtained significant improvement in their skin lesions leaving pigmentary changes. After this satisfactory response was achieved, the same dose of UVB was administrated as a maintenance
therapy with longer intervals between exposures. Histopathological examination of three patients revealed decreased numbers of inflammatory cells in both the epidermis and the dermis after the treatment. Immunohistochemical study showed that CD1a+/HLA-DR+ dendritic cells were present throughout the lesional epidermis before the treatment. In contrast, after the treatment, the dendritic cells in the epidermis were CD1a+/
HLA-DR-. Although it remains unclear why only the expression of
HLA-DR antigen was eliminated
after treatment, we presume that this loss of
HLA-DR antigen expression by epidermal Langerhans cells was, in part, responsible for the improvement of skin lesions. This preliminary study suggests that UVB
phototherapy is an effective treatment for patients with early-stage
mycosis fungoides.