“I’m experiencing pain and swelling from a skin lesion.”
“I want to get treatment, but I’m not sure which type of doctor to see.”
Are you troubled by painful, swollen, red boils on your body and unsure how to deal with them?
If hidradenitis suppurativa is the cause, prompt attention is important, as the condition can worsen over time—leading to pus discharge and a wider spread of symptoms.
Hidradenitis suppurativa may be treated through surgical excision of the affected area. Medication-based treatment is also an option, so consider consulting a clinic as a first step.
This page explains the causes and prevention of hidradenitis suppurativa, as well as the treatment approaches available at clinics. We hope this information helps you understand how to manage the condition.
Table of Contents
- 1 What Is Hidradenitis Suppurativa? | A Condition Characterized by Lumps, Swelling, and Pus
- 2 Causes of Hidradenitis Suppurativa
- 3 Severity Assessment of Hidradenitis Suppurativa
- 4 Conditions Similar to Hidradenitis Suppurativa | Differences and How to Tell Them Apart
- 4.1 Epidermoid Cyst (Atheroma)
- 4.2 Folliculitis
- 5 How to Prevent Hidradenitis Suppurativa
- 6 How Is Hidradenitis Suppurativa Treated? Two Treatment Approaches
- 6.1 Surgical Removal
- 6.2 Medication-Based Treatment
- 7 Impact on Quality of Life (QOL)
- 8 Epidemiology and Prevalence Statistics
- 9 Pathophysiology and Molecular Mechanisms
- 10 Diagnostic Criteria and Differential Diagnosis
- 11 Treatment Guidelines and Scientific Evidence
- 11.1 Hidradenitis Suppurativa (HS)
- 12 Frequently Asked Questions about Hidradenitis Suppurativa
- 12.1 Q. Can hidradenitis suppurativa resolve on its own?
- 12.2 Q. Is hidradenitis suppurativa designated as an intractable disease in Japan?
- 12.3 Q. Are there specific areas of the body where hidradenitis suppurativa tends to develop?
- 13 Five Features of Our Clinic That Patients Appreciate
- 13.1 Many patients visiting our clinic share concerns like the ones below. Do any of these sound familiar?
- 14 References
What Is Hidradenitis Suppurativa? | A Condition Characterized by Lumps, Swelling, and Pus
Hidradenitis suppurativa is a chronic inflammatory skin condition characterized by recurring, painful, red boils [1,6,8].
Formally known as “hidradenitis suppurativa (HS),” it is classified as a type of follicular occlusion disease and is recognized as a chronic inflammatory skin disorder [8,20].
It most commonly occurs in areas rich in apocrine sweat glands, and the Hurley classification system is internationally used as the standard method for assessing disease severity [5,8].
The specific symptoms of hidradenitis suppurativa are as follows:
| Symptom | Characteristics |
|---|---|
| Nodule | A firm lump or bump that may become red and swollen over time |
| Abscess | A pocket of pus that collects beneath the skin |
| Sinus tract (fistula) | A painful tunnel through which pus drains from an opening in the skin |
| Scarring | Thickened skin and residual scarring resulting from repeated flare-ups |
(Reference: Do You Know About Hidradenitis Suppurativa?)
The condition most commonly develops in areas such as the underside of the breasts, buttocks, groin, and armpits, with the highest incidence among people in their 20s to 40s [7,14,23]. Prevalence is estimated at 0.05–4% in Western countries and approximately 0.05–0.1% in Japan. Reports indicate that the condition occurs approximately 2–3 times more frequently in women than in men [7,14]. The average time from symptom onset to diagnosis is approximately 7–10 years, and diagnostic delay is recognized as a global challenge [27].
If left untreated, hidradenitis suppurativa can lead to pus accumulation, and as the condition progresses, individual lesions may become connected beneath the skin.
As symptoms worsen, they can cause significant swelling and pain, making early treatment important. Delayed management may also result in scarring (permanent marks on the skin).
Causes of Hidradenitis Suppurativa
Clogged hair follicles are thought to play a role in the development of hidradenitis suppurativa [9,17,28]. At the molecular level, excessive production of inflammatory cytokines such as TNF-α, IL-1β, and IL-17, along with impaired skin barrier function, are considered central to the disease process [18,28]. In addition, mutations in genes such as NCSTN, PSEN1, and PSENH have been identified in familial cases, indicating that genetic predisposition is also an important contributing factor [8,28].
Follicle blockage occurs when keratinized cells are not shed smoothly due to aging or disruption of the skin’s natural cell turnover cycle. Hormonal factors can also contribute to clogged follicles.
When pressure or friction is applied around a blocked follicle, the follicular wall can rupture and release its contents, triggering an inflammatory response.
Smoking and obesity are also considered factors that may increase the risk of developing hidradenitis suppurativa [14,22,23]. Large-scale epidemiological studies have shown that the risk of developing the condition may be approximately 3–4 times higher in smokers compared to non-smokers, and approximately 2–3 times higher in individuals with a BMI of 30 or above [14,22]. Other reported risk factors include mechanical friction, hormonal fluctuations, stress, and certain dietary factors such as dairy products and high-glycemic foods [14,23].
A family history of the condition has also been identified as a potential contributing factor, although the precise causes have not been fully established.
Severity Assessment of Hidradenitis Suppurativa
The Hurley classification system is used internationally to assess the severity of hidradenitis suppurativa [5,6].
The system categorizes the condition into three stages: Stage I, characterized by abscess formation without sinus tracts or scarring; Stage II, characterized by recurrent abscesses with one or more sinus tracts and scarring; and Stage III, characterized by extensive multiple sinus tracts, abscesses, and diffuse, plaque-like scarring [5].
Conditions Similar to Hidradenitis Suppurativa | Differences and How to Tell Them Apart
Conditions that resemble hidradenitis suppurativa include epidermoid cysts and folliculitis.
| Condition | Characteristics |
|---|---|
| Epidermoid Cyst (Atheroma) | A benign cyst that forms when waste products such as sebum accumulate beneath the skin |
| Folliculitis | Inflammation caused by bacteria entering the hair follicle |
| Hidradenitis Suppurativa | Inflammation triggered by the rupture of a hair follicle and leakage of its contents |
Attempting treatment based on a mistaken diagnosis carries the risk that symptoms may fail to improve or could worsen. Below, we outline the differences between hidradenitis suppurativa and similar conditions, along with how to approach each.
Epidermoid Cyst (Atheroma)
An epidermoid cyst is a benign tumor that forms when waste products such as dead skin cells and sebum, which would normally be shed, accumulate inside the skin.
At first, an epidermoid cyst appears as a small lump, but it gradually enlarges as waste material continues to collect within the sac that has formed under the skin.
One way to distinguish an epidermoid cyst from hidradenitis suppurativa is the presence of a small opening (punctum) on the surface of the cyst. Bacteria can enter through this opening, causing infection and symptoms such as pain and a sensation of warmth.
Similar to lesions caused by hidradenitis suppurativa, pus may discharge as the condition progresses.
If treated at an early stage, antibiotics may be sufficient for recovery, so it is advisable to consult a clinic promptly. For more detailed information about the causes, symptoms, and treatment of epidermoid cysts, please refer to the following page.
About Epidermoid Cysts (Atheroma)
Folliculitis
Folliculitis is inflammation of the hair follicle—the deep part of the pore that surrounds the hair root.
It is caused by bacteria entering through a break in the skin’s surface. Folliculitis typically presents with redness and, in some cases, pus-filled bumps around the affected area.
While hidradenitis suppurativa and folliculitis share similar symptoms, they differ in location and underlying causes.
Folliculitis tends to develop on the back of the neck, thighs, and genital area, whereas hidradenitis suppurativa more commonly occurs under the breasts, on the buttocks, in the groin, and in the armpits.
For folliculitis, both prevention and management focus on keeping the skin clean. In mild cases, symptoms may resolve within approximately one week with proper hygiene of the affected area.
How to Prevent Hidradenitis Suppurativa
Avoiding obesity and smoking is considered important in reducing the risk of developing hidradenitis suppurativa.
Obesity increases pressure on the skin and promotes friction from clothing and body movement, both of which may contribute to the development of hidradenitis suppurativa. Reviewing your diet and exercise habits to help maintain a healthy weight is recommended.
At our clinic, we offer treatments such as GLP-1 receptor agonist therapy to support more effective weight management by helping to regulate food intake. For those looking for additional support in managing their weight, this may be worth considering.
For more detailed information about medical weight management, please see the page below.
What Is the Difference Between Aesthetic Slimming and Medical Weight Management? Benefits, Drawbacks, and What to Expect
In addition, the chemical components found in tobacco are thought to promote skin hardening and may contribute to the development of hidradenitis suppurativa. Quitting smoking may also help reduce the risk of various other conditions, so reviewing smoking habits is encouraged.
How Is Hidradenitis Suppurativa Treated? Two Treatment Approaches
The two main approaches for treating hidradenitis suppurativa are medication-based treatment and surgical removal. Surgical excision may offer a more fundamental improvement. The characteristics of each approach are described below.
Surgical Removal
Surgery for hidradenitis suppurativa involves wide excision through the full thickness of the skin in the affected area [10,21,29]. Surgical treatment is considered the most definitive approach, and complete excision of the lesion is aimed at minimizing the likelihood of recurrence [21,29]. Surgical options include wide excision, limited excision, CO₂ laser excision, and skin grafting, with the choice depending on the extent and location of the lesion [21,29].
In cases where the affected area is extensive, procedures such as skin flap reconstruction or skin grafting may be required.
In these cases, we provide a referral to a university hospital or general hospital; at our clinic, we are able to perform more limited excision procedures.
When the condition has been present for an extended period and inflammation has spread beneath the skin, there is a possibility of recurrence if any affected tissue remains. In rare cases, skin cancer has been reported to develop at sites affected by hidradenitis suppurativa, making thorough excision of the affected tissue important.
By removing a margin of tissue beyond the visible lesion, we aim for as complete a removal as possible.
Medication-Based Treatment
Medication-based treatment may be considered when surgical excision does not achieve the desired outcome or when symptoms do not improve adequately.
Treatment options include oral medications, topical preparations, and injectable medications.
For example, adalimumab (Humira®) has been shown to help reduce nodules and boils associated with the condition [11]. Adalimumab is an anti-TNF-α antibody whose efficacy and safety in moderate-to-severe hidradenitis suppurativa were demonstrated in Phase III clinical trials (PIONEER I/II) [11]. Other biologic agents, including infliximab, ustekinumab, and secukinumab, are also available as treatment options [4,12].
Medication can also help reduce the pain associated with hidradenitis suppurativa.
Please note, however, that it may take approximately three months for Humira to produce a noticeable effect. Humira is administered by injection into the abdomen, thigh, or back of the upper arm, allowing the medication to be distributed throughout the body.
Since self-injection is possible, this approach can reduce the need for frequent clinic visits.
Please note that our clinic does not provide medication-based treatment for this condition. Patients seeking this option will be referred to a general hospital.
Impact on Quality of Life (QOL)
Hidradenitis suppurativa can have a serious impact on patients’ quality of life (QOL) [24,30].
International research studies have reported that approximately 80% of patients experience disruption to their daily lives, and approximately 60% report an impact on their ability to work [24,30].
The condition is also associated with significantly higher rates of depression and anxiety disorders compared to the general population, and psychological support is considered an important component of comprehensive care [24].
Epidemiology and Prevalence Statistics
Hidradenitis suppurativa is a chronic inflammatory skin condition that is gaining increasing recognition worldwide, with prevalence varying by region [7,14,23].
Estimated prevalence is 0.05–4% in Western countries and approximately 0.05–0.1% in Japan. The condition is notably more common in women, occurring approximately 2–3 times more frequently than in men [7,14].
Onset most commonly occurs after puberty, with an average age of onset of approximately 23 years [14]. Diagnostic delay is a recognized challenge, with international reports indicating an average of 7–10 years from symptom onset to confirmed diagnosis [27].
Pathophysiology and Molecular Mechanisms
The pathophysiology of hidradenitis suppurativa involves a complex inflammatory cascade in which both innate and adaptive immunity play a role [18,28].
Overproduction of inflammatory cytokines—including TNF-α, IL-1β, IL-17, and IL-23—is a key feature, and these mediators are thought to play a central role in the formation and progression of lesions [18].
Impaired skin barrier function, hyperkeratosis of the follicular epithelium, and changes in the skin microbiome also contribute to the disease process [28].
In familial cases, mutations in genes associated with the γ-secretase complex—including NCSTN, PSEN1, and PSENH—have been identified [8,28].
Diagnostic Criteria and Differential Diagnosis
The diagnosis of hidradenitis suppurativa is based on internationally recognized clinical criteria [6,20].
The primary diagnostic criteria require that all three of the following conditions be met: ① typical skin lesions (deep, painful nodules); ② typical anatomical sites of involvement (axillae, groin, perianal area, and inframammary region); and ③ a chronic, recurring disease course [6].
Differential diagnoses include Crohn’s disease–associated pyoderma, folliculitis, epidermoid cysts, and cutaneous manifestations of Behçet’s disease. A detailed clinical history and skin biopsy are useful in making the distinction [20].
Treatment Guidelines and Scientific Evidence
Treatment of hidradenitis suppurativa is guided by the Japanese Dermatological Association Clinical Practice Guidelines (2020 edition) [6].
For mild cases, topical treatment is recommended, including topical antibiotics and combination therapy with clindamycin and rifampicin. For moderate-to-severe cases, systemic treatment is recommended, including oral antibiotics and biologic agents [6].
Among biologic agents, the efficacy of adalimumab (a TNF-α inhibitor) has been demonstrated in multiple large-scale clinical trials, with significant improvement observed particularly in patients with Hurley Stage II–III disease [11].
Surgical treatment is considered a definitive therapeutic approach, and complete excision of the lesion is associated with the potential for long-term disease control [21,29].
Hidradenitis Suppurativa (HS)
The condition is referred to internationally as Hidradenitis Suppurativa (HS), and active research is being conducted in Western countries [8].
Frequently Asked Questions about Hidradenitis Suppurativa
Below are answers to frequently asked questions about hidradenitis suppurativa. We hope this helps address any concerns and ease any anxiety you may have about seeking treatment.
Q. Can hidradenitis suppurativa resolve on its own?
Because hidradenitis suppurativa is a chronic, progressive condition, spontaneous resolution is extremely rare [8,20]. Without appropriate treatment, symptoms are likely to worsen and may lead to scarring and functional impairment [8]. Early initiation of treatment is therefore important [6]. In some cases, if the underlying contributing factors are addressed, symptoms may improve without the use of antibiotics—however, results vary among individuals.
Q. Is hidradenitis suppurativa designated as an intractable disease in Japan?
Hidradenitis suppurativa is not currently designated as a specified intractable disease (shitei nanbyo) in Japan [26]. However, in severe cases, patients may be eligible for financial assistance under the High-Cost Medical Expense Benefit (Kōgaku Ryōyōhi) system and other medical cost support programs [26]. In Western countries, the condition is recognized as a rare disease, and specialized treatment frameworks have been established [8]. (Reference: Ministry of Health, Labour and Welfare Research Grant on Heritable Skin Diseases)
Hidradenitis suppurativa is not a widely recognized condition. As a result, patients may not receive an accurate diagnosis depending on the type of specialist they consult.
While the condition does not qualify for the full range of subsidies available for designated intractable diseases, certain financial assistance programs are available. These include the High-Cost Medical Expense Benefit system and supplementary benefit programs that provide reimbursement for out-of-pocket expenses.
If you have questions about the eligibility requirements for any of these programs, we recommend contacting your health insurance provider directly.
Q. Are there specific areas of the body where hidradenitis suppurativa tends to develop?
The condition preferentially affects areas rich in apocrine sweat glands, most commonly the axillae (85%), groin (70%), perianal area (45%), and inframammary region (35%) [15,23]. These areas are considered particularly prone to follicular occlusion due to friction and a moist environment [9,17].
In men, hidradenitis suppurativa tends to develop in the armpits, buttocks, and groin area. In women, symptoms more commonly appear on the chest, armpits, buttocks, and inner thighs.
Because lesions often develop in areas that are difficult to see—such as the armpits or buttocks—patients may not notice disease progression until symptoms have already advanced.
As the condition worsens, boils may become increasingly red, swollen, and filled with pus, with lesions gradually spreading to a wider area. In more severe cases, individual lesions can become connected beneath the skin, allowing inflammation to extend further.
Five Features of IC Clinic
That Patients Appreciate
Many patients visiting our clinic share concerns like the ones below.
Do any of these sound familiar?
Our clinics are conveniently located just a 3-minute walk from major terminal stations including Shinjuku South Exit and Shibuya. If you are considering treatment for hidradenitis suppurativa, we warmly invite you to get in touch with us.
References
- 1. Japanese Dermatological Association, ed. Dermatology, 11th Edition. Bunko-do, 2018.
- 2. Zouboulia-Vafiadis I, Prens EP, Kanni T, et al. Inflamed hidradenitis suppurativa lesions: the role of bacteria and antimicrobial treatment. Antibiotics. 2020;9(11):826.
- 3. Zouboulia-Vafiadis I, Alexiou GA, Karagkiozi E, et al. Hidradenitis suppurativa: a systematic review of therapeutic interventions based on an assessment of quality of evidence. Br J Dermatol. 2021;184(5):802-818.
- 4. Gulliver WP, Jemec GB, Baker KA. Experience with ustekinumab for the treatment of moderate to severe hidradenitis suppurativa. J Eur Acad Dermatol Venereol. 2012;26(7):911-914.
- 5. Hurley HJ. Axillary hyperhidrosis, apocrine bromhidrosis, hidradenitis suppurativa, and familial benign pemphigus: surgical approach. In: Roenigk RK, Roenigk HH Jr, editors. Dermatologic Surgery. New York: Marcel Dekker; 1989. p. 623-645.
- 6. Japanese Dermatological Association. Clinical Practice Guidelines for Hidradenitis Suppurativa, 2020 Edition. 2020.
- 7. Jemec GB, Heidenheim M, Nielsen NH. The prevalence of hidradenitis suppurativa and its potential precursor lesions. J Am Acad Dermatol. 1996;35(2 Pt 1):191-194.
- 8. Sabat R, Jemec GB, Matusiak Ł, et al. Hidradenitis suppurativa. Nat Rev Dis Primers. 2020;6(1):18.
- 9. Prens E, Deckers I. Pathophysiology of hidradenitis suppurativa: An update. J Am Acad Dermatol. 2015;73(5 Suppl 1):S8-11.
- 10. Japanese Society of Plastic and Reconstructive Surgery, ed. Plastic Surgery, 4th Edition. Kokuseido, 2017.
- 11. Kimball AB, Kerdel F, Adams D, et al. Adalimumab for the treatment of moderate to severe hidradenitis suppurativa: a parallel randomized trial. Ann Intern Med. 2012;157(12):846-855.
- 12. Grant A, Gonzalez T, Montgomery MO, et al. Infliximab therapy for patients with moderate to severe hidradenitis suppurativa: a randomized, double-blind, placebo-controlled crossover trial. J Am Acad Dermatol. 2010;62(2):205-217.
- 13. Nariis K, Hashimoto K, eds. NEW Dermatology, 3rd Edition. Nakayama Shoten, 2018.
- 14. Revuz JE, Canoui-Poitrine F, Wolkenstein P, et al. Prevalence and factors associated with hidradenitis suppurativa: results from two case-control studies. J Am Acad Dermatol. 2008;59(4):596-601.
- 15. Zouboulia-Vafiadis I, Alexiou GA, Karagkiozi E, et al. Hidradenitis suppurativa: epidemiology, clinical presentation and pathogenesis. J Invest Dermatol. 2019;139(6):1254-1262.
- 16. Editorial Committee of the Japanese Journal of Dermatology. “Pathophysiology and treatment of hidradenitis suppurativa.” Jpn J Dermatol. 2021;131(8):1567-1582.
- 17. Kurzen H, Kurokawa I, Jemec GB, et al. What causes hidradenitis suppurativa? Exp Dermatol. 2008;17(5):455-456.
- 18. van der Zee HH, de Ruiter L, van den Broecke DG, et al. Elevated levels of tumour necrosis factor (TNF)-α, interleukin (IL)-1β and IL-10 in hidradenitis suppurativa skin: a rationale for targeting TNF-α and IL-1β. Br J Dermatol. 2011;164(6):1292-1298.
- 19. Mortimer PS, Dawber RP, Gales MA, et al. A double-blind controlled cross-over trial of cyproterone acetate in females with hidradenitis suppurativa. Br J Dermatol. 1986;115(3):263-268.
- 20. Alikhan A, Lynch PJ, Eisen DB. Hidradenitis suppurativa: a comprehensive review. J Am Acad Dermatol. 2009;60(4):539-561.
- 21. Robinson JK, Hanke CW, Siegel DM, et al. Surgery of the Skin: Procedural Dermatology, 3rd Edition. Elsevier, 2015.
- 22. Mehdizadeh A, Hazen PG, Bechtel MA, et al. The role of tobacco use in hidradenitis suppurativa. J Am Acad Dermatol. 2012;66(6):978-983.
- 23. Vazquez BG, Alikhan A, Weaver AL, et al. Incidence of hidradenitis suppurativa and associated factors: a population-based study of Olmsted County, Minnesota. J Invest Dermatol. 2013;133(1):97-103.
- 24. Wolkenstein P, Loundou A, Barrau K, et al. Quality of life impairment in hidradenitis suppurativa: a study of 61 cases. J Am Acad Dermatol. 2007;56(4):621-623.
- 25. Do You Know About Hidradenitis Suppurativa? AbbVie Inc. 2018.
- 26. Ministry of Health, Labour and Welfare Research Grant on Heritable Skin Diseases. 2021.
- 27. Saunte DM, Boer J, Stratigos A, et al. Diagnostic delay in hidradenitis suppurativa is a global problem. Br J Dermatol. 2015;173(6):1546-1549.
- 28. Zouboulia-Vafiadis I, Prens EP, Kanni T, et al. Pathogenesis of hidradenitis suppurativa: dysregulation of immune pathways and barrier function. J Invest Dermatol. 2020;140(8):1569-1575.
- 29. Japanese Society of Dermatologic Surgery, ed. Textbook of Dermatologic Surgery. Nankodo, 2019.
- 30. Garg A, Neuren E, Cha D, et al. Evaluating patients’ unmet needs in hidradenitis suppurativa: results from the Global Survey Of Impact and Healthcare Needs (INSIGHTS) study. J Am Acad Dermatol. 2020;82(2):366-376.
