Follicular mucinosis successfully treated by photodynamic therapy: Two case reports.

Follicular mucinosis is an epithelial reaction pattern characterized by follicular mucin accumulation. Follicular mucinosis may occur in a primary form or a secondary form associated with skin lymphoma, especially mycosis fungoides. This report describes two patients with these two forms of follicular mucinosis, who both had an excellent response to photodynamic therapy. The condition changes of the secondary follicular mucinosis patient were followed up by repeated pathological biopsies. The expression of CD103, a specific marker of tissue-resident memory T cells, was found to decline when the lesions improved. These results indicate an association between efficacy and pathological changes during the treatment of secondary follicular mucinosis.