Interesting Open Access Hidradenitis Suppurativa (HS) Reads – May 2025

 

In total, 104 #hidradenitissuppurativa (HS)-related publications appeared in PubMed in May 2025. Of these, approx. 47% (49/104) were open access.

1: HS Tunnels

🔍 What Was the Study About?

This review paper explains how tunnels, which are a common but poorly understood feature of HS, can actively cause and promote inflammation and worsen disease.

🧩What Are HS Tunnels?

• Tunnels (also called sinus tracts and fistulas) are deep, inflamed (swollen) channels under the skin.
• They are lined with skin-like cells and often leak pus, are painful, and can connect different areas under the skin, i.e., press down in one area and pus/blood can come out millimetres, centimeters, or even inches away from where you pushed.
• They commonly appear in more severe HS, and are difficult to treat.
• They can be very distressing for people.

🧠 What Causes Tunnels?

Researchers have found that tunnels:

• Can actively cause inflammation in HS.
• Lined with specialized skin cells (called keratinocytes) that can act like cells in wounds or even cancers.
• Certain types of immune cells (such as T-cells, B-cells, and neutrophils) can leak into tunnels and keep the inflammation going.
• Associated with abnormal wound healing and the inability of the skin to repair itself.
• Started by issues in stem cells from hair follicles and fibroblasts (cells involved in scarring and tissue structure).

🦠 The Role of Bacteria in HS Tunnels

• Tunnels have an imbalanced skin microbiome (known as “dysbiosis”), with a rise in certain bacteria like Prevotella and Fusobacterium .
• These bacteria can form biofilms, which are difficult to treat with antibiotics.
• This may prolong inflammation and cause tunnels to resist healing.

💉 How to Treat Tunnels?

• Some of the currently available biological drugs are ineffective when it comes to tunnels.
• Surgery, such as deroofing, can be an effective treatment for tunnels.
• Research into new medications that target cells or bacteria in tunnels is ongoing.

⚠️ Why Does This Matter?

Research has shown that tunnels are key players in causing inflammation in HS and highlights the need for therapies that target tunnels. In addition, research has given us a better understanding of how tunnels form and behave.

📌MainMessage

More research is needed to help us to focus on treating HS tunnels better through early treatment, targeted therapies, and new approaches.

Link: https://www.sciencedirect.com/science/article/pii/S2667026725000049

Citation: Vecin N, Balukoff NC, Yaghi M, Gonzalez T, Sawaya AP, Strbo N, Tomic-Canic M, Lev-Tov H, Pastar I. Hidradenitis Suppurativa Tunnels: Unveiling a Unique Disease Entity. JID Innov. 2025 Jan 21;5(3):100350. doi: 10.1016/j.xjidi.2025.100350. PMID: 40034103.

 

2. Low Satisfaction with Medical Care Among Patients with HS

📋 What Was the Study About?

This research from Germany explored whether patients with HS are satisfied with the medical care they receive and how that compares to patients with psoriasis. The study also asked dermatologists (doctors who specialize in skin) for their views on HS care.

👥 Who Was Involved?

• 124 people with HS
• 133 people with psoriasis
• 76 dermatologists treating the patients (All were based in Germany)

🔍What Did the Researchers Do?

• They used anonymous surveys to measure satisfaction levels in patients (with HS and psoriasis) and doctors with the following:
  • Overall care
  • Specific treatments (like creams or medications)
  • Information provided about the disease
• The researchers also looked at differences based on where patients received care (university hospital, municipal hospital, or private practice).

🧾 What Were the Key Findings?

👥 Patient Satisfaction

• Patients with HS reported lower satisfaction with their care than patients with psoriasis.
  • Average rating for HS care: 6.7/10
  • Average rating for psoriasis care: 8.6/10
• Patients with HS were especially dissatisfied with:
  • Systemic treatments (like pills or injections)
  • The information they received about HS

🩺 Doctor Satisfaction

• Dermatologists were also less satisfied with HS care than with psoriasis care.
  • They were especially unhappy with:
    • Limited treatment options for HS
    • Challenges referring patients with HS to specialized care

⚠️ Why Does This Matter?

• This study clearly shows clearly that patients and doctors are frustrated with current HS care.
• The research findings highlight the need for:
  • Better treatment options for HS
  • More education and resources for both patients and doctors, nurses, and healthcare workers
  • Faster access to effective care

📌 MainMessage

People with HS feel less supported, less informed, and less satisfied with their treatment than people with psoriasis. Improving medical care for HS requires more effective treatments and better communication between patients with HS and healthcare professionals.

Link: https://onlinelibrary.wiley.com/doi/10.1111/jdv.20718

Citation: Wolk K, Cugno G, Kokolakis G, Schneider-Burrus S, Wilsmann-Theis D, Assaf K, Moessner R, Kromer C, Bechara FG, Abu Rached N, Peitsch WK, Schneider LC, Happ A, Siddi V, Kubitzki D, Groß D, Friedrich M, Vandersee S, Asadullah K, Sabat R. Low satisfaction with medical care among patients with hidradenitis suppurativa: A multicenter study. J Eur Acad Dermatol Venereol. 2025 May 2. doi: 10.1111/jdv.20718. Epub ahead of print. PMID: 40318085.

 

3. HS in a Pediatric Population

🔍 What Was the Study About?

This study from Italy looked at how HS affects children and teenagers compared to adults. Researchers focused on symptoms, quality of life, and emotional health.

👥 Who Was Involved?

• In total, 601 patients with HS, of whom
  • Approx. 10% (60) were under 18 years old
  • The rest were adults, used for comparison

🧾What Were the Key Findings?

🔹Diagnosis and Disease Characteristics

• The pediatric (child) patients with HS were mostly female (80%).
• I in children, the average age of HS onset was around 12 years old.
• Diagnostic delays were shorter in children (average 2 years) than adults (average 7 years).
• Children had fewer associated illnesses (known as comorbidities), but the severity of HS (number of lesions, pain levels, etc.) was similar between the children and adults

🔹 Quality of Life and Mental Health

• Adults reported worse overall quality of life than children.
• However, HS still had a significant psychological impact on children, of whom:
  • Approx. 44% had signs of emotional distress
  • Approx. 18% were likely experiencing depression
• Pediatric patients with HS reported issues with pain levels, self-esteem, social life, and the impact on school.

🔹 Obesity and Risk Factors

• Obesity was more common in the pediatric group (35%).
• HS lesions in the lower abdomen were more common in children.

⚠️ Why Does This Matter?

Even though children with HS may have slightly less emotional and quality-of-life impact than adults, HS affects their lives considerably and can interfere with school, friendships, and their mental health.

✅ How to Help Children and Teenagers with HS?

• Early diagnosis and education for families are crucial.
• Children with HS need access to:
  • Multidisciplinary care (dermatologists, psychologists, paediatricians, others)
  • Mental health support
  • Obesity and nutrition counseling and support
  • Ongoing monitoring and age-appropriate treatments

📌 MainMessage

Children and teenagers with HS experience considerable physical and emotional challenges. Better disease awareness, earlier diagnosis, and more specific care are key to improving their lives.

Link: https://www.pagepress.org/journals/dr/article/view/10086/9463

Citation: Dattolo A, Sampogna F, Mastroeni S, Fania L, Ciccone D, Abeni D. Health-related quality of life and clinical characteristics of hidradenitis suppurativa in a pediatric population. Dermatol Reports. 2025 May 23;17(2). doi:10.4081/dr.2024.10086. Epub 2024 Oct 16. PMID: 40420710.

 

4. Impact of Surgery on Quality of life in Patients with HS

🔍 What Was the study about?

This study from Germany looked at how surgery affects the quality of life for people with HS. The researchers wanted to know if surgery alone (without any biological medications) could help reduce pain and improve daily life for people.

👥 Who Was Involved in the Study?

• 82 patients with moderate to severe HS (Hurley stage II or III)
• None had received biologic treatments before surgery
• Most had surgery in the groin, underarms, or buttocks/perianal area
• Majority healed by secondary intention (ie, where the surgical wound is left open to heal from the bottom up), and some had skin grafts

🩺 What Did They Do?

All patients had wide excision surgery to remove HS-damaged skin. They were checked:

• Before surgery
• 3 months after surgery
• 6 months after surgery

Patients with HS completed surveys used to rate:

• Quality of life (using the Dermatology Life Quality Index [DLQI])
• Pain levels
• Disease severity

Dermatologists also completed surveys regarding their satisfaction levels.

📈 What Did the Results Show?

✅ Improved quality of life

• The DLQI score dropped from an average score of 11.7 before surgery to:
  • 8.3 at 3 months
  • 4.7 at 6 months
• More than half of patients with HS improved by at least 5 points on the DLQI scale

✅Less Pain

• Pain scores dropped from 3.0 (out of 10) to 1.1 at 6 months

✅ Less Disease Activity

• HS severity scores dropped significantly
• About 24% of patients were free of lesions 6 months after surgery

🔄 Comparison Between Post-Surgical Healing Methods

The researchers compared the two surgical healing methods, secondary intention and skin grafts, and found that:

➡️ Both worked, but healing by secondary intention showed slightly better results for people’s quality of life. ➡️ Pain scores were similar in both groups.

⚠️ Why Does This Matter?

• This is one of the largest studies showing that surgery alone (ie, without biologics) can significantly improve life for people with HS
• Surgery should be part of a multimodal approach: combining medical treatments and surgery gives the best outcomes

📌 MainMessage

Surgery for HS can:

• Improves quality of life
• Reduce pain
• Lowers disease severity

Surgery is most helpful for patients with more advanced HS (with scarring), and should be considered as a key part of long-term treatment planning.

Link: https://www.mdpi.com/2075-1729/15/5/769

Citation: Ocker L, Abu Rached N, Koller A, Frost C, Käpynen R, Bechara FG. The Impact of Surgery on Quality of Life in Hidradenitis Suppurativa: Results from a Prospective Single-Center Study. Life (Basel). 2025 May 12;15(5):769. doi: 10.3390/life15050769. PMID: 40430197 .

 

5. Quality and Readability of Online Health Resources for HS

🔍 What Was the Study About?

This study from Australia looked at how good and easy-to-understand online information is for people searching about HS.

As HS affects intimate and sensitive parts of the body, people with HS often search online for disease information as they can do so anonymously, privately, and safely. Therefore, the researchers wanted to know if the:

• Information is understandable (readable) for most people?
• Content is accurate and up-to-date?

💻What Did the Researchers Do?

• The researchers used Google to search for terms like “hidradenitis suppurativa” and “acne inversa” (how HS is called in mainly German-speaking regions and elsewhere)
• They reviewed the first 240 search results, choosing 115 websites aimed at patients with HS.
• Each website was rated on its:
  • Readability (measured by what grade level of education a person needs to understand it)
  • Quality (how trustworthy, clear, and up-to-date was the information about HS)

📊 What Did They Find?

📚 Readability: Too Complex

• Most websites required at least a high school or college reading level.
• Only one website ( WebMD ) met the recommended 6 ^th -grade reading level.
• The average reading level was about 11th ^grade , which is too difficult for many readers.

✅ Quality: Needs Improvement

• Many websites lacked author names or references (sources ought to be available for cross-checking)
• Only 18% mentioned key quality indicators (ie, who wrote the information, the date it was last updated, and source reliability).
• Less than 20% mentioned secukinumab, a new (since 2023) approved treatment for HS.
• Some of the best-ranked websites (like DermNet ) were of high quality but too hard to read (for most people).

⚠️ Why Does This Matter?

People living with HS often search online because:

• Diagnosis is often delayed
• There’s limited awareness among general doctors
• Patients want to be informed and take part in treatment decisions

When online health information is too complex to understand or contains outdated information, it can:

• Confused people
• Lead to delays in treatment
• Prevent people from getting the help they need

📌MainMessage

Online resources for HS are often too hard to read and unreliable or out-of-date. People need simpler, clearer, and more accurate websites to help people make informed choices and get the care they need and deserve sooner.

Link: https://onlinelibrary.wiley.com/doi/10.1111/ajd.14533

Citation: Xiong G, McMullen E, Shenouda C, Gupta S, Moshkovich M, Soliman J, Mukovozov I, Dumont S, Julanon N, Alhusayen R, Piguet V. Quality and Readability of Online Health Resources for Hidradenitis Suppurativa: A Cross-Sectional Analysis. Australas J Dermatol. 2025 May 30. doi: 10.1111/ajd.14533. Epub ahead of print. PMID: 40444659.

 

6. HS and Ocular Diseases

👁️ What Was This Study About?

This study looked at whether people with HS are more likely to have eye problems (ocular diseases) compared to people without HS.

🔍What Did the Researchers Do?

• They used a large database of electronic medical records (TriNetX) to study over 57,000 people, comprising:
  • 28,986 people with and without HS (the groups were matched by age, sex, and smoking status
• They examined how often different eye conditions occurred in each group.

🧾 What Did They Find?

People with HS had a significantly higher risk of several eye diseases, including:

Eye Condition	How Much More Common in HS?
Vision problems (blurred, distorted)	2× more likely
Refractive issues (needing glasses)	3.5× more likely
Lacrimal (tear duct) disorders	3.5× more likely
Glaucoma	3× more likely
Blepharitis (eyelid inflammation)	3× more likely
Cataracts (age-related)	Over 3× more likely
Eye pain and inflammation	2–3× more likely

Even less common conditions like blindness, hordeolum (stye), and dry eye were seen more often in people with HS.

💡 Why Is This Important?

• HS can affect more than the skin, including the eyes.
• Most people with HS don’t get asked about eye symptoms during clinic visits.

This study suggests that doctors should pay more attention to eye health in patients with HS, even if the person hasn’t mentioned any problems with their eyes yet.

🧠 What Might Be Causing These Eye Problems?

• HS involves long-term inflammation, which may affect blood flow in the eyes or lead to changes in the tear system.
• Smoking, obesity, and metabolic issues (all of which are common in people with HS) may also contribute.
• Some patients with HS may not notice eye issues unless screened during medical checkups.

📌 Main Message:

People with HS are at a higher risk for a wide range of eye conditions, including those that can affect vision. Doctors treating patients with HS should routinely ask about eye symptoms and refer patients with HS to eye specialists when needed.

Link: https://medicaljournalssweden.se/actadv/article/view/42716

Citation: Von Stebut-Marx J, Preissner R, Schneider-Burrus S, Preissner S. Hidradenitis Suppurativa and Ocular Diseases: Real-world Evidence of 57,972 Patients. Acta Derm Venereol. 2025 May 19;105:adv42716. doi: 10.2340/actadv.v105.42716. PMID: 40390258.

 

7. Differentiating the Role of Inflammation in HS from Other Inflammatory Skin Diseases

🔍 What Is This Review About?

This review explores how HS is different from other skin conditions (such as psoriasis or eczema), even though they all involve inflammation (swelling). The goal is to better understand what makes HS unique so that treatments can be improved.

➡️ What’s Different About Inflammation in HS?

• In many inflammatory skin diseases, the immune system plays a big role.
• In HS, the inflammation also involves problems with skin structure and wound healing, (in addition to immune system overactivity).
• Unlike psoriasis (which is mostly driven by immune cells), HS shows a mixed pattern involving:
  • Hair follicle blockages
  • Bacterial imbalance (dysbiosis)
  • Long-term (chronic) skin damage
  • Deeper inflammation in tunnels under the skin

🧾 Key Findings:

• HS involves more than inflammation: It includes scarring, infections, and tunnels, which makes it harder to treat.
• Certain immune signals are more active in HS than in other skin diseases, especially those related to wound repair and tissue remodeling.
• HS lesions often contain fibrosis (scarring) and biofilms (clusters of bacteria protected by a slimy layer), which are absent in other skin conditions like eczema.

💡 Why does this matter?

• Standard treatments used for other skin diseases don’t always work for HS, as HS has a different kind of inflammation.

📌 MainMessage

Current treatments used for HS are limited and more specific treatments for HS are needed to improve people’s lives.

Link: https://linkinghub.elsevier.com/retrieve/pii/S0022202X25004506

Citation: Byrd AS, Moreau JM, Petukhova L, Frew J. Differentiating the Role of Inflammation in Hidradenitis Suppurativa from that in Other Inflammatory Skin Diseases. J Invest Dermatol. 2025 May 24:S0022-202X(25)00450-6. doi: 10.1016/j.jid.2025.04.009. Epub ahead of print. PMID: 40411510.

 

8. Assessing Clinicians’ Knowledge of HS

🔍 What Was This Study About?

This study from Poland looked at how well doctors from different medical specialties recognize and diagnose HS. Despite having clear clinical features, many patients with HS are misdiagnosed (several times) and/or wait years to get a correct diagnosis. This survey aimed to test how familiar different doctors are with HS and where the biggest gaps in knowledge exist.

👩‍⚕️ Who Was Surveyed?

• In total, 655 doctors from a variety of specialties in Poland, including:
  • Dermatologists
  • General Practitioners (GPs)
  • Gynaecologists
  • Urologists
  • Surgeons
• Survey participants included both experienced specialists and doctors still in training.
• Doctors were shown images of actual cases of HS (Hurley stages I–III) and asked to identify the disease.

📊 Key Findings:

⚠️ Diagnostic accuracy was highly variable by specialty:

• Severe armpit HS (Hurley III) :
  • Most (97%) of dermatologists got it right
  • Only 49% of GPs and 31% of gynaecologists identified it correctly
• Genital HS in Males (Hurley II) :
  • Only 34.5% of all doctors diagnosed HS
  • Most misdiagnosed it as boils, sexually transmitted infections (STIs), or tumors
• Mild Genital HS in Females (Hurley I) :
  • Less than 30% of all doctors correctly identified HS
  • Even among dermatologists, only 58% got it right
• For buttocks HS lesions (Hurley III):
  • Many doctors mistook HS for pilonidal cysts or Crohn’s disease
  • Only 30% of all respondents correctly diagnosed hs

👨‍⚕️ Career Experience Didn’t Guarantee Accuracy:

• Dermatologists in training performed better than senior dermatologists.
• In other specialties, experience made little difference as doctors often misdiagnosed HS regardless of years in practice.

📉 Why does this matter?

• People with HS see multiple doctors and on average wait 7–10 years before getting a correct diagnosis.
• Misdiagnosis can lead to:
  • Inappropriate treatments
  • Delayed care
  • Emotional harm (eg being told it’s an STI)
  • Worsening of the disease

✅ What needs to change?

1. Improved education about HS in medical school and specialist training
2. Ongoing learning for experienced doctors, especially in family medicine, gynaecology, urology, and surgery
3. More awareness of early signs of HS to catch it before it gets severe
4. Use of visual tools and clinical images to improve recognition skills
5. Referral checklists to help non-dermatologists send patients to the right specialist early

📌 MainMessage

Many doctors, including specialists, struggle to recognize HS, especially in its early or less typical forms. This leads to delayed diagnoses and poorer outcomes for patients with HS. Targeted education and better training are urgently needed to help doctors diagnose HS early and provide timely, effective treatment.

Link: https://www.mdpi.com/2077-0383/14/9/3171

Citation: Knecht-Gurwin K, Gurwin A, Łyko M, Drewa T, Kielan W, Mastalerz-Migas A, Stojko R, Szepietowski JC, Matusiak L. An Assessment of Clinician Knowledge of Hidradenitis Suppurativa: Insights from a Multidisciplinary Survey Study. J Clin Med. 2025 May 3;14(9):3171. doi: 10.3390/jcm14093171. PMID: 40364202.

 

9. Assessing Long-Term Pain Reduction in HS with Secukinumab

🔍 What Was the Study About?

This research examined whether secukinumab, a biologic medication, helps reduce pain over time in people with moderate to severe HS. People with HS report pain as the most troublesome, which can greatly affect quality of life (QoL).

🔍 How Was the Study Done?

• The data came from two large clinical trials: SUNSHINE and SUNRISE.
• During these trials, over 1000 patients with HS were randomly given:
  • Secukinumab every 2 weeks
  • Secukinumab every 4 weeks
  • Or a placebo (inactive treatment)
• After 16 weeks, those on placebo were switched to secukinumab.
• The study lasted 52 weeks (1 year).
• Researchers measured:
  • Skin pain using a 0–10 scale (Numerical Rating Scale)
  • Use of pain medications
  • Quality of life (Dermatology Life Quality Index [DLQI] and EuroQOL- 5 Dimesion [EQ-5D])

📊 What Did They Find?

✅ Secukinumab Reduced Pain in Patients with HS

• People on secukinumab had greater pain reduction than those on placebo.
• Improvements began as early as week 4 and continued through week 52.
• By week 52, more patients reported mild or no pain (NRS ≤ 3.3).

📉 Less Need for Pain Medication

• Fewer patients needed painkillers (like non-steroidal anti-inflammatory drugs [NSAIDs], paracetamol, or tramadol) during the study.
• Opioid use also went down.

👍 Improved Quality of Life

• Patients with less pain reported better quality of life scores.
• Those who started with severe pain saw the biggest benefit from secukinumab.

💡 Why Does This Study Matter?

• Pain from HS affects people in many ways, including sleep, mental health, work, and daily life.
• Until now, few treatments have targeted HS pain directly.
• Secukinumab may offer a non-opioid option for long-term pain relief.
• The improvement happened in patients with HS who had used other treatments before.

❗ What Are the Study’s Limitations?

• The analysis was “post hoc,” meaning it was not the primary goal of the original trials.
• Most trial participants were white, so results may not reflect the full diversity of people with HS.
• Pain is a subjective experience and can vary a lot.

📌 Key Takeaway:

Secukinumab helps reduce pain, improve quality of life, and reduces the need for pain medications in people with moderate to severe HS.

Link: https://link.springer.com/article/10.1007/s13555-025-01426-x

Citation: Ingram JR, Szepietowski JC, Matusiak L, Kokolakis G, Wozniak MB, Ortmann CE, Martinez AL, Ravichandran S, Thomas N, Alarcon I, Pieterse CC, Alam MS, Ioannides D, Kimball AB. Assessing Long-Term Pain Reduction with Secukinumab in Moderate to Severe Hidradenitis Suppurativa: A Post Hoc Analysis of the SUNSHINE and SUNRISE Phase 3 Trials. Dermatol Ther (Heidelb). 2025 May 15. doi: 10.1007/s13555-025-01426-x. Epub ahead of print. PMID: 40372667.

 

10. Management and Burden of HS in Italy

🔍 What Was the Study About?

This study looked at how HS affects patients in Italy, including how it’s managed, how it impacts daily life, and how much it costs patients and the healthcare system.

👥 Who Was Involved in This Study?

• A total of 48 adult patients with HS from four specialized centers in Italy
• The study included both patients with mild and moderate-to-severe HS
• The researchers used both:
  • Clinical and patient-reported data (how people feel)
  • Administrative health data (doctor visits, treatments, costs)

📊 Key Findings

1. 🕒 Delayed Diagnosis

• Patients with moderate-to-severe HS waited nearly 2 years on average to be diagnosed.
• Those with mild HS waited less than 1 year.

2. 😖 Poor Symptom Control in Severe Cases

• Only 40.7% of people with moderate-to-severe HS had their symptoms under control
• Most (95.2%) people with mild HS had good control

3. 😐Quality of Life (QoL)

• QoL was significantly worse in moderate-to-severe cases:
  • Average score: 11.8 (on a 0–30 scale)
  • Compared to 8.0 in mild cases
• The longer someone had HS, the worse their quality of life was.

4. 💶 Costs to the Healthcare System (Direct Costs)

• Moderate-to-severe HS: €2,214 per year
• Mild HS: €873 per year
• Most of these costs were for medications, especially antibiotics and biologics

5. 💸 Out-of-Pocket Costs (Not Covered by Health Insurance)

• Nearly all patients paid extra out-of-pocket for:
  • Dressings, creams, antibiotics, supplements, psychological support
• Patients with moderate-to-severe HS spent more, especially on surgery and therapy

6. 💼 Lost Work and Income (Indirect Costs)

• Moderate-to-severe HS: average of €2,435 lost per year
• Mild HS: €262 lost per year
• People with more severe disease lost twice as many workdays as those with milder disease

✅ Key Messages

• HS causes significant physical, emotional, and financial strain
• Delays in diagnosis and lack of effective treatments lead to worse health and higher costs
• People with moderate-to-severe HS carry the heaviest burden
• Biologic medications may reduce the need for surgery and emergency care, improving long-term outcomes
• More education, early diagnosis, and access to advanced care are needed

📌 MainMessage

HS can deeply affect people’s lives and wallets. This study shows how important it is to catch the disease early, treat it properly, and support patients’ mental and physical health along the way.

Link: https://link.springer.com/article/10.1007/s13555-025-01407-0

Citation: Balato A, Venturini M, Scalvenzi M, Foti C, Maifredi G, Creazzola SS, Antonacci S, Tonelli A, Valsecchi D, Vassellatti D, Cipelli R, Ori A, Casoli L. Management and Burden of Hidradenitis Suppurativa: An Italian Hybrid Real-World Study. Dermatol Ther (Hei