Assess the efficacy of fractional ablative CO2 therapy combined with topical steroids in HS patients with Hurley stage I or stage II disease.

Hidradenitis suppurativa (HS) is a chronic, oftentimes debilitating inflammatory skin condition that presents with painful lesions in intertriginous areas of the body. The reported prevalence of HS in the U.S. is around 1-4%. Medical therapies, which typically consist of topical or systemic antibiotics, hormone- regulating drugs, and immunomodulators, are initially used to control the disease but HS can be recalcitrant to these modalities in the long-term. Optimizing management of mild-moderate HS is crucial to prevent disease progression and improve patients' quality of life.

This is an open label prospective study aimed at understanding the efficacy of fractional ablative CO 2 laser therapy combined with steroids in HS patients with mild-moderate (Hurley stage I or stage II) disease. Study subjects will be patients with mild-moderate HS. The subjects will undergo a minimum of 3 treatment sessions and up to 5 treatment sessions at 4-6 week intervals. Patients will be informed of the aim of the study and the risks and benefits of the intervention. All questions that the subjects have will be answered and patients will be informed that their participation is completely voluntary. Subjects who agree and consent to participate in the study will partake in the treatment sessions. EMLA™ 5% cream will be applied as a topical anesthetic to the affected area 30 minutes prior to treatment. Fractional ablative CO 2 laser therapy will be performed and the HS lesions that will be treated include: non-inflammatory and inflammatory nodules, sinus tracts, abscesses, and scars. The fractional CO 2 laser treatment will be followed by immediate application of triamcinolone acetonide 40 mg/ml to the treatment area. Patients will be evaluated before the 1st treatment session and before every subsequent treatment session. The last study visit will occur 1 month after the completion of the last treatment session. Before each laser treatment, physicians will perform a complete assessment of Hurley stage and HS-PGA score. The number of non-inflammatory nodules, inflammatory nodules, abscesses, and sinus tracts in the treated area will be counted. Patients will evaluate their pain and itch level and provide their impression on whether their HS has improved, worsened, or stayed the same. Patients will also complete the Patient Global Assessment Item questionnaire. For scars, objective scar assessment will be performed using the Fibrometer ® , Elastimeter ® , and SkinColorCatch ® measurement tools. The Fibrometer ® measures tissue induration and skin stiffness. The Elastimeter ® induces constant skin deformation and returns a measurement of skin elasticity. The SkinColorCatch ® is a colorimeter that allows skin tone to be measured. Measurements of scars will be taken before each treatment session. In addition, the scars will be assessed using the VSS and POSAS scales by the investigators. Patients will also complete a POSAS self- assessment at each treatment session. Pictures of the treatment area will be taken during each visit with permission from the patients to analyze the effects of the treatment.

Inclusion Criteria:

• 18 years of age or older with a diagnosis of HS for at least 6 months
• Subjects who provide informed consent to undergo the procedure
• Patients with mild to moderate HS (Hurley stage I or stage II)
• Must not have been using topical or systemic therapies for 2 weeks prior to starting treatment on the affected area
• The use of antiseptic washes and intralesional steroid injections for acute lesions (rescue therapy) will be allowed

Exclusion Criteria:

• Under the age of 18
• Pregnant women
• Severe HS (Hurley stage III)
• Using topical or systemic medications within the 2 weeks prior to starting therapy
• History of adverse reactions to laser resurfacing or steroids
• Other diseases besides HS which require ongoing systemic therapies
• Active infection within the treatment area