This is a phase 2a, open label study.

As psoriasis and Hidradenitis Suppurativa (HS) share multiple inflammatory pathways, the investigators hypothesize that the use of topical roflumilast 0.3% foam is a safe and efficacious option as a monotherapy for patients with mild disease and as add-on therapy for maintenance and flares in patients with moderate to severe disease. The study will include correlative analysis to study gene expression profiling before and after therapy.

With limited topical treatment options available for mild HS and for flare control, the investigators hypothesize that topical roflumilast, a phosphodiesterase-4 inhibitor (PDE4) inhibitor, is a safe and efficacious monotherapy or add-on therapy in HS patients.

The study will investigate the efficacy, safety, and toxicity of topical roflumilast 0.3% foam applied to affected areas once a day as monotherapy in Hurley stage I HS patients and as add-on therapy with daily application for Hurley stage II and III HS patients on 4 months of stable treatment regimen via changes in gene expression compared to pre-treatment using Ribonucleic acid (RNA) derived from tape strip collection.

Inclusion Criteria:

• Must understand the risks and the benefits/purpose of the study and provide signed and dated informed consent.
• Must be 18 years at time of signing informed consent form.
• Willing to participate in all required evaluations and procedures in the study including the ability to apply topical medication without difficulty.
• Patients must have a diagnosis of HS based upon the clinical criteria of a history of more than or equal 5 typical lesions (erythematous papules, nodules, or abscesses) in flexural sites with a recurring nature over time.
• Patients must be candidate for topical therapy defined by active Hurley stage I or Hurley stage II/III with active disease after an adequate trial of systemic antibiotics/hormonal/immunomodulatory or biologic therapy.
• Patient is required to be on stable dose of concomitant therapy for at least 3 months before enrollment and throughout the study period.
• Females of childbearing potential must have a negative urine pregnancy test at baseline visit and be on adequate contraception throughout the study time.

Exclusion Criteria:

• Concomitant use of topical antibiotics, topical corticosteroids, resorcinol, benzoyl peroxide, vitamin D analogs, Hibiclens wash (except for emollients) within 1 week of enrollment.
• Increasing or changing dosing for concurrent therapy agents within 90 days before study day 0 and during the study period.
• History of any clinically significant (as determined by the investigator) cardiac, endocrinologic, pulmonary, neurologic, psychiatric, hepatic, renal, hematologic, immunologic, or other major uncontrolled disease.
• Any condition, including the presence of laboratory abnormalities, which places the subject at unacceptable risk if he/she were to participate in the study or confounds the ability to interpret data from the study.
• Pregnant or breastfeeding.
• Prior major surgery or major life-threatening medical illness within 2 weeks.
• Active hepatitis B or C infection with detectible viral nucleic acid in the blood or known Human Immunodeficiency Virus (HIV) positivity.
• Patients with known active malignancy.
• Any severe systemic illness requiring Intravenous (IV) antibiotics within the two weeks prior to initiation of the study drug.
• Active substance abuse or a history of substance abuse within 6 months prior to screening.
• Use of any investigational drug within 4 weeks prior to randomization, or 5 pharmacokinetic/pharmacodynamic half-lives, if known (whichever is longer).