Hidradenitis Suppurativa

ETIOLOGY​​

Genetics​​

• A twin study reported a heritability of HS of 77%, which is higher than what has been previously reported for psoriasis, (68%) and RA (60-75%), and on par with Crohns (75%). 33052394

  • note to self: not particularly savvy at interpreting these heritability statistics​​​

CLINICAL FEATURES

• ​​Patients with HS can present with sepsis-like features -- meet SIRS criteria, leukocytosis, tachycardia -- but RARELY have fever. 38395228​​

Impact on Pregnancy

• Some evidence HS is associated with worse maternal and fetal outcomes during pregnancy even when controlling for maternal comorbidities that were significantly higher in HS patients than non-HS patients. 39412794 

TREATMENT​​

Surgical

Definitions​​​

• Recently, an attempt to standardize surgical definitions was proposed to clarify what is being performed. 36811866​​

IL-17 Inhibitors

Risk of Fungal Infections

Risk of Candida and overall fungal infections with interleukin-17 inhibitors in the treatment of hidradenitis suppurativa: A systematic review and meta-analysis. J Am Acad Dermatol. 2025. PMID: 39710114.

• Among 2,272 patients across 9 clinical trials:

  • Overall fungal infection rate was 7.4%

  • Candida infection rate was 6.1%

• Bimekizumab had the highest infection rates (12.7% fungal, 8.1% Candida), especially at higher doses.

• Secukinumab had lower rates (4.4% fungal, 1.7% Candida).

• The elevated risk may stem from IL-17’s role in antifungal immunity, particularly the dual inhibition of IL-17A and IL-17F by bimekizumab.

Emerging Therapies

Efficacy and Safety of the Heat Shock Protein 90 Inhibitor RGRN-305 in Hidradenitis Suppurativa: A Parallel-Design Double-Blind Trial. JAMA Dermatol. 2024. PMID: 38055242.

Special Patient Populations 39725212

Pregnancy

• Safe options: Topical antiseptics (chlorhexidine), zinc supplementation, certain antibiotics (cephalexin, azithromycin), and biologics like adalimumab.

• Avoid: Tetracyclines (e.g., doxycycline), metronidazole, and resorcinol due to risks to the fetus.

Breastfeeding

• Safe: Metformin, adalimumab, and most antibiotics (e.g., amoxicillin/clavulanic acid, azithromycin) with caution.

• Avoid or limit: High-dose prednisone (>20 mg), long-term doxycycline; time breastfeeding around dosing if needed.

Pediatrics

• First-line: Topical antibiotics, benzoyl peroxide, and adalimumab (for ages ≥12).

• Caution: Anti-androgens should be used primarily in post-pubertal adolescents; metformin may be used in cases with metabolic syndrome.

Malignancy

• Preferred: Tetracyclines, metformin, and biologics (e.g., anti-TNFs, secukinumab, ustekinumab) in consultation with oncology.

• Caution: Immunosuppressants require multidisciplinary decision-making, particularly if recent or high-risk cancer.

Tuberculosis (TB)

• Screening: Required before starting biologics or prolonged corticosteroids.

• Preferred: Non-TNF biologics (e.g., secukinumab, ustekinumab) for high TB-risk patients; complete latent TB treatment before anti-TNF initiation.

Hepatitis B/C

• Screening: Required prior to immunosuppressive or biologic therapy.

• Safe: Ciprofloxacin, TMP-SMX, and doxycycline; metformin is generally safe unless cirrhosis is present.

HIV

• Safe: Doxycycline, TMP-SMX, metformin, and cautious biologic use (adalimumab, infliximab).

• Avoid or monitor: Rifampin due to antiretroviral interactions; coordinate care with infectious disease specialists.

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