Hidradenitis Suppurativa (HS): ICD-10 Code L73.2, Hurley Staging & Wound Care Management

ICD-10 Code for Hidradenitis Suppurativa

What Is Hidradenitis Suppurativa? Definition and Pathophysiology

Hidradenitis suppurativa (HS) is a chronic, recurrent, debilitating inflammatory skin disease characterised by painful nodules, abscesses, and draining sinus tracts in areas rich in apocrine glands — primarily the axillae, inguinal folds, inframammary region, perianal/perineal area, and buttocks. The condition was historically attributed to apocrine gland dysfunction, but current evidence identifies the primary pathological event as follicular occlusion and rupture, followed by a dysregulated innate and adaptive immune response.

HS is not an infective condition per se, though secondary bacterial colonisation — predominantly with Staphylococcus aureus, coagulase-negative staphylococci, anaerobes, and streptococci — contributes to ongoing inflammation and wound management complexity.

Epidemiology and Risk Factors

HS affects approximately 1% of the global population, with onset typically in the second or third decade of life. It is approximately three times more common in women than men. Prevalence may be underestimated due to patient embarrassment and delayed diagnosis — a median diagnostic delay of 7–10 years is frequently reported in the literature.

Key risk factors include:

• Smoking: Present in 70–90% of HS patients; smoking worsens disease severity and reduces treatment response to systemic antibiotics.
• Obesity: Body mass index is strongly correlated with disease severity; mechanical friction from skin-to-skin contact in skin folds may be a contributing factor.
• Metabolic syndrome: HS is independently associated with type 2 diabetes, dyslipidaemia, and cardiovascular disease.
• Family history: Approximately 30–40% of patients have a first-degree relative with HS.
• Female sex hormones: Disease activity often correlates with the menstrual cycle, implicating androgen and oestrogen pathways.

In Singapore, the psychosocial burden of HS has been documented in studies from the National Skin Centre (NSC) and published in the Annals Academy of Medicine Singapore, showing significant impairment in quality of life, work productivity, and mental health.

Hurley Staging System: Classification of HS Severity

IHS4 Score: A Complementary Severity Tool

The International Hidradenitis Suppurativa Severity Score (IHS4) provides a dynamic, quantifiable measure of HS activity that the static Hurley classification cannot capture. It is calculated as:

The IHS4 is endorsed by the 2024 European S2k guidelines as the preferred disease activity score for treatment monitoring and biologic prescribing decisions.

Treatment Ladder by Hurley Stage

Hurley Stage I: Topical and Local Measures

• Topical clindamycin 1% solution/lotion: Applied twice daily to affected areas; reduces surface bacterial load and inflammation. Evidence from RCT by Clemmensen (1983) — still cited in European guidelines.
• Antiseptic washes: Chlorhexidine gluconate 4% wash or triclosan-containing soap; daily use to reduce follicular bacterial colonisation.
• Intralesional triamcinolone: For acute flares; 10 mg/mL injected into active nodules/abscesses; reduces pain and inflammation within 48–72 hours.
• Lifestyle modification: Weight loss, smoking cessation, loose-fitting breathable clothing, pain management.
• Limited surgery: Incision and drainage for acute painful abscesses provides temporary relief but does not prevent recurrence; deroofing of individual sinus tracts offers better outcomes.

Hurley Stage II: Systemic Antibiotics

• Oral tetracyclines: Lymecycline 408 mg once daily or doxycycline 100 mg once daily for 12 weeks; used as monotherapy for mild-moderate Stage II.
• Combination clindamycin + rifampicin: Clindamycin 300 mg + rifampicin 300 mg, both twice daily for 10–12 weeks. A retrospective study from NSC Singapore demonstrated improvement rates of 71–86% with this regimen in an Asian HS population (Alikhan et al. regional data; NSC local study).
• Combination clindamycin IV: For severe flares; short-term IV clindamycin recommended in 2024 European S2k guidelines as a bridging strategy.
• Zinc gluconate: 90 mg daily has anti-inflammatory and anti-androgenic effects; limited but positive evidence in Stage I–II.

Hurley Stage III (and Refractory Stage II): Biologic Therapy

• Adalimumab (anti-TNF-α): First approved biologic for HS. PIONEER I and II trials (Kimball et al., NEJM 2016) demonstrated clinical response (HiSCR — ≥50% reduction in abscess and nodule count) in 41.8% vs. 26% placebo at 12 weeks. Dosing: 160 mg week 0, 80 mg week 2, then 40 mg weekly. ICD-10 secondary code: Z79.899.
• Secukinumab (anti-IL-17A): EMA-approved for HS (2023); Phase III SUNSHINE and SUNRISE trials showed HiSCR response in ~45% at week 16.
• Bimekizumab (anti-IL-17A/F): EMA-approved 2023; BE HEARD I and II trials showed superior HiSCR75 responses (~60–70%) at 16 weeks. The 2024 European S2k guidelines include bimekizumab as a first-choice biologic.
• Infliximab (anti-TNF-α): Off-label; used in refractory severe HS where adalimumab has failed.

Surgical Options for HS

• Deroofing: Unroofing of sinus tracts using scissors or scalpel; local anaesthesia; low recurrence in small-area Stage II disease.
• Wide excision: For Stage III or large-area Stage II; resection of all involved tissue with primary closure, skin grafting, or secondary intention healing. SGH and NUHS dermatology and plastic surgery teams perform these procedures in Singapore.
• Laser therapy: Nd:YAG 1064 nm laser has RCT evidence for reduction in HS lesion count; CO₂ laser deroofing is an alternative to surgical deroofing.

Wound Care for Hidradenitis Suppurativa

Despite HS being a medical (dermatological) condition, its physical manifestations — draining sinus tracts, open abscesses, post-surgical wounds, and areas of maceration — require skilled wound care nursing. The IWII 2022 framework and EWMA guidance on complex wounds are applicable.

Managing Active Draining Sinus Tracts

Draining sinus tracts produce variable amounts of serous, seropurulent, or purulent exudate. Management principles:

• PHMB cleansers (Prontosan): Gentle irrigation of sinus tracts and surrounding skin reduces bacterial bioburden without cytotoxicity. PHMB is the recommended wound cleanser in the 2022 IWII consensus for critically colonised chronic wounds.
• Foam dressings (Mepilex, Biatain Silicone): Absorb moderate-to-heavy exudate; soft silicone adhesive reduces trauma to fragile periwound skin. Non-adhesive variants preferred in axillary or groin locations where skin is occluded.
• Alginate or hydrofibre (Aquacel) for cavity packing: Used to pack deep sinus openings to manage exudate and prevent premature skin bridge formation.
• Antimicrobial dressings: Silver-containing dressings (Mepilex Ag, Aquacel Ag) for sinus tracts with signs of local infection (NERDS criteria); Medihoney for MRSA-positive wounds or malodorous tracts.

Post-Surgical HS Wound Care

Wide excision wounds in HS may heal by secondary intention over weeks to months. Management requires:

• Initial debridement and regular wound bed preparation
• Superabsorbent dressings (Eclypse, Zetuvit Plus) for heavily exuding post-excision wounds
• Negative Pressure Wound Therapy (NPWT) to reduce wound volume and promote granulation in large cavities — particularly in axillary and inguinoperineal regions
• Skin grafting wound care where split-thickness skin grafts are applied: non-adherent silicone interfaces (Mepitel) to protect graft and donor site

Quality of Life and Pain Management in HS

HS carries one of the highest disease burdens among all dermatological conditions as measured by the Dermatology Life Quality Index (DLQI). Studies from NSC Singapore document comparable or higher DLQI impairment than psoriasis or atopic eczema in the local population. Pain is universal — the nociceptive component from active abscesses and the chronic pain from scar tissue both require structured assessment and management. Multimodal analgesia, including NSAIDs, gabapentinoids, and referral to pain medicine, may be required for Stage II–III patients.

Singapore Clinical Services for Hidradenitis Suppurativa

NSC (National Skin Centre) is the primary specialist hub for HS in Singapore, with dermatologists conducting biologic prescribing and clinical trials. NSC has published Singapore-specific data on the clindamycin-rifampicin combination and on the psychosocial burden of HS in Asian patients. SGH dermatology and plastic surgery provide multidisciplinary HS care for complex surgical cases. NUHS (National University Health System) dermatology at NUH offers HS management including biologic initiation. KKH sees paediatric and adolescent HS — the condition can present from puberty onwards. TTSH and CGH dermatology outpatient services manage Stage I–II HS in the community.

Frequently Asked Questions: Hidradenitis Suppurativa

Is hidradenitis suppurativa contagious?

No. HS is an inflammatory condition, not an infectious one. While secondary bacterial colonisation occurs in active lesions, the condition itself cannot be transmitted from person to person. Patients should be explicitly reassured, as social stigma and misconceptions about contagion significantly contribute to the psychosocial burden of HS.

How is HS different from recurrent boils (furunculosis)?

Recurrent furunculosis involves discrete follicle-based infections, typically on hair-bearing skin, caused by Staphylococcus aureus. HS involves a systemic inflammatory dysregulation affecting characteristic apocrine gland-bearing sites with a pattern of scarring, sinus tract formation, and interconnected lesions that is distinct from simple furunculosis. MRSA furunculosis and HS can co-exist, but the diagnostic distinction affects long-term management.

Does adalimumab work for all HS patients?

Adalimumab (Humira) achieves clinical response (HiSCR — ≥50% reduction in total abscess and nodule count without increase in abscess or draining fistula count) in approximately 40–50% of patients in pivotal Phase III trials. Predictors of response include higher baseline disease activity, absence of smoking, and lower BMI. Patients failing adalimumab may respond to secukinumab or bimekizumab, targeting the IL-17 pathway rather than TNF-α.

What dressings should be avoided in HS wound care?

Avoid highly adhesive dressings (traditional adhesive foam or hydrocolloid dressings) on periwound skin, as repeated adhesive trauma worsens skin fragility and can trigger new lesions in susceptible areas. Occlusive dressings that trap heat and moisture should be avoided in axillary or groin sites. Fibre-shedding dressings (traditional gauze) should not be used in open sinus tracts, as retained fibres may serve as foreign bodies perpetuating inflammation.

References

1. Zouboulis CC, Desai N, Emtestam L, et al. European S1 guideline for the treatment of hidradenitis suppurativa/acne inversa. J Eur Acad Dermatol Venereol. 2015;29(4):619–644.
2. Zouboulis CC, Bechara FG, Dickinson-Blok JL, et al. European S2k guidelines for hidradenitis suppurativa/acne inversa — part 2: Treatment. J Eur Acad Dermatol Venereol. 2024. doi:10.1111/jdv.20249.
3. Kimball AB, Okun MM, Williams DA, et al. Two phase 3 trials of adalimumab for hidradenitis suppurativa. N Engl J Med. 2016;375(5):422–434.
4. Jemec GBE. Hidradenitis suppurativa. N Engl J Med. 2012;366(2):158–164.
5. Tan LF, Tay YK. The effect of oral clindamycin and rifampicin combination therapy in patients with hidradenitis suppurativa in Singapore. Int J Dermatol. 2016;55(4):e220–222. [NSC Singapore study, PMC5779281]
6. Fung A, Tan NN, Tey HL. Psychosocial impact and treatment trends of hidradenitis suppurativa in Singapore. Ann Acad Med Singapore. 2022.
7. Poli F, Jemec GBE, Revuz J. Clinical presentation. In: Jemec GBE, Revuz J, Leyden JJ, eds. Hidradenitis Suppurativa. Berlin: Springer; 2006.
8. National Skin Centre Singapore. Hidradenitis suppurativa services. Available at: www.nsc.com.sg. Accessed May 2026.