Photodynamic therapy, a promising treatment approach for cutaneous infectious granulomas

Cutaneous infectious granulomas are mainly caused by fungi and bacteria. Antibiotics are the primary therapeutic choices for these diseases, but drug-resistant pathogens have become increasingly prevalent. Thus, there is a need to explore novel approaches to treat cutaneous infectious granulomas. Photodynamic therapy (PDT) is widely used as a treatment for various kinds of skin diseases, and evidence has been accumulating that PDT is also effective for the treatment of cutaneous infectious granulomas. In this narrative review, we sought to summarize the recent literature concerning the applications and mechanisms of PDT in the treatment of cutaneous infectious granulomas. Clinical and basic research has demonstrated that PDT is an effective approach in treating fungal infections such as sporotrichosis and chromoblastomycosis. In addition, PDT is also used to treat atypical mycobacterial infections such as Mycobacterium marinum. PDT can significantly shorten the duration of antibiotics treatment, resulting in diminishment of adverse effects. The potential mechanisms of PDT are to kill the pathogens directly or elicit modulatory effects on the immune microenvironments. We conclude that PDT is a promising therapeutic choice for the treatment of cutaneous infectious granulomas.