Intralesional photodynamic therapy in hidradenitis suppurativa: Getting closer to the target

The successful treatment of hidradenitis suppurativa (HS) with intralesional photodynamic therapy (IL-PDT) has been previously reported in some case series published a few years ago. We present additional data and patient outcome for this form of PDT.

This is an observational retrospective study including all patients diagnosed with HS and treated with IL-PDT in the Hospital Universitari Son Espases from February 2019 to February 2020. Under local or general anesthesia, 5-aminolevulinic acid (5ALA) in gel 2 % or solution 1 % was introduced in the lesion. After two hours, the lesion was intralesionally irradiated (1.4 W, fluence 168 J/cm2) with the tip of a 0.4-mm thick optical fiber connected to a continuous 630-nm diode laser. The main outcome variable was the result (remission, improvement or no change) for each lesion 3 months after the therapy. The result at 6 months and the side effects were secondary outcomes. A multivariate analysis was carried out in order to obtain adjusted odds ratios for no change vs improvement or remission at 3 months for significant variables.

A total of 117 lesions (28 nodules and 89 fistulae) were treated in 42 patients. At 3 months, 26 lesions (22.2 %) had resolved, 73 (62.4 %) had improved in size or symptoms, and 18 (15.4 %) experienced no change. The most frequent side effects were skin burns (53 lesions, 45.3 %), and abscess formation (8 lesions, 6.8 %). In the multivariate analysis, significant variables for no benefit were: a higher International Hidradenitis Suppurativa (IHS4) score, active smoking and gluteal and inguinal location.

Although our results did not present the level of remission of the previous studies, IL-PDT was useful in most of our patients. Early interventions in patients with lower inflammatory burden were the most valuable.