“I am experiencing pain and swelling from a skin lesion.”
“I want to get treatment, but I don’t know which medical specialty to visit.”
Are you troubled by painful, swollen, red bumps on your body and unsure how to address them?
If hidradenitis suppurativa (HS) is the cause, the condition can worsen over time—pus may develop and symptoms may spread—so prompt attention is important.
With hidradenitis suppurativa, surgical removal of the affected tissue may be an option. Medical treatment is also available, so we encourage you to consider consulting a clinic.
This page explains the causes, prevention, and clinical treatment options for hidradenitis suppurativa. We hope it helps you understand how to manage the condition.
What Is Hidradenitis Suppurativa? | A Condition Causing Lumps, Swelling, and Pus
Hidradenitis suppurativa is a skin condition characterized by recurring, painful, red, swollen bumps [1,6,8].
Formally known as “hidradenitis suppurativa (HS),” it is classified as a chronic inflammatory skin disease within the group of follicular occlusion disorders [8,20].
It tends to occur in areas rich in apocrine sweat glands, and the Hurley staging system is internationally used as the standard method for assessing disease severity [5,8].
The specific symptoms of hidradenitis suppurativa are as follows.
| Symptom | Description |
|---|---|
| Nodules | Firm lumps or bumps under the skin that may become red and swollen over time |
| Abscesses | Pus-filled cavities that form beneath the skin |
| Sinus tracts (fistulas) | Tunnel-like passages through which pus drains, often accompanied by pain |
| Scarring | Thick, hardened scar tissue that forms as a result of repeated flare-ups |
(Reference: Do You Know About Hidradenitis Suppurativa?)
The condition commonly develops under the breasts, on the buttocks, in the groin, and in the armpits, and most often affects 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. It has been reported that women are affected approximately 2–3 times more often than men [7,14]. The average time from symptom onset to diagnosis is approximately 7–10 years, and delayed diagnosis is recognized as a global concern [27].
If left untreated, hidradenitis suppurativa can lead to pus accumulation, and as the condition progresses, lesions beneath the skin may become interconnected.
As symptoms worsen, they can cause significant swelling and pain, making early treatment important. Delayed management may also result in scarring (known as cicatrices) in the affected areas.
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, the overproduction of inflammatory cytokines such as TNF-α, IL-1β, and IL-17, along with impaired skin barrier function, is considered central to the pathophysiology [18,28]. In addition, genetic mutations in genes such as NCSTN, PSEN1, and PSENH have been identified in familial cases, suggesting that genetic predisposition is also an important contributing factor [8,28].
Follicular blockage can occur when dead skin cells are not shed smoothly due to aging or disruption of the skin cell turnover cycle. Hormonal changes can also contribute to clogged follicles.
When pressure or friction is applied to a blocked follicle, the follicular wall can rupture, allowing its contents to leak out and trigger inflammation.
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 in smokers is approximately 3–4 times higher than in 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 noted as a potential trigger, although the precise causes have not been fully established.
Severity Assessment of Hidradenitis Suppurativa
The Hurley staging system is used internationally to assess the severity of hidradenitis suppurativa [5,6].
The condition is classified into three stages: Stage I (abscess formation without sinus tracts or scarring), Stage II (recurrent abscesses with single or multiple sinus tracts and scarring), and Stage III (diffuse involvement with multiple interconnected sinus tracts, abscesses, and extensive scarring with broad areas of induration) [5].
Conditions Similar to Hidradenitis Suppurativa | Differences and How to Tell Them Apart
Conditions that resemble hidradenitis suppurativa include epidermoid cysts (atheroma) and folliculitis.
| Condition | Description |
|---|---|
| Epidermoid Cyst (Atheroma) | A benign cyst that forms when waste products such as sebum accumulate beneath the skin |
| Folliculitis | Inflammation of the hair follicle caused by bacterial entry into the follicle |
| Hidradenitis Suppurativa | Inflammation caused by the rupture of a hair follicle and leakage of its contents |
Attempting treatment based on an incorrect diagnosis may result in the condition failing to improve or worsening. Below, we outline how hidradenitis suppurativa differs from similar conditions and how each should be approached.
Epidermoid Cyst (Atheroma)
An epidermoid cyst is a benign growth that forms when waste products such as dead skin cells and sebum, which would normally be shed, accumulate inside a pocket beneath the skin.
Initially, an epidermoid cyst appears as a small lump, but as waste continues to accumulate inside the sac, it gradually grows larger over time.
One distinguishing feature from hidradenitis suppurativa is the presence of a small opening (punctum) in the skin over the cyst. Bacteria can enter through this opening, causing infection and symptoms such as pain and warmth.
As with the bumps caused by hidradenitis suppurativa, pus may also develop as the condition progresses.
When identified at an early stage, the condition may be managed with antibiotics. Visiting a clinic as soon as possible is important. For more information on the causes, symptoms, and treatment options for epidermoid cysts, please refer to the following page.
About Epidermoid Cysts (Atheroma)
Folliculitis
Folliculitis is inflammation of the hair follicle—the deeper part of the pore that surrounds the hair root.
It is caused by bacteria entering through a break in the skin surface. Symptoms of folliculitis include redness and pus-filled spots around the affected follicles.
Although folliculitis and hidradenitis suppurativa share similar symptoms, they differ in the areas affected and their underlying causes.
Folliculitis tends to occur on the back of the neck, the thighs, and around the genital area. Hidradenitis suppurativa, on the other hand, more commonly develops under the breasts, on the buttocks, in the groin, and in the armpits.
For folliculitis, keeping the skin clean is key both for prevention and management. Mild cases may resolve on their own within approximately one week with proper cleansing of the affected area.
How to Help Prevent Hidradenitis Suppurativa
To help reduce the risk of developing hidradenitis suppurativa, avoiding obesity and smoking is considered important.
Obesity increases pressure on the skin and promotes friction from clothing, which may raise the likelihood of developing hidradenitis suppurativa. Reviewing your diet and exercise habits to help maintain a healthy weight is worthwhile.
Our clinic offers treatments such as GLP-1 therapy to help regulate food intake as part of an approach to weight management. If you are looking for support with obesity, consulting with us about treatment options may be helpful.
For more details on medical weight management, please see the following page.
In addition, chemical components in cigarettes can promote hardening of the skin and may contribute to the development of hidradenitis suppurativa. Quitting smoking may also help reduce the risk of other health conditions, so reviewing your smoking habits is recommended.
How Is Hidradenitis Suppurativa Treated? Two Main Approaches
The two main treatment approaches for hidradenitis suppurativa are medication and surgical removal. Surgical excision may offer a more fundamental resolution. The characteristics of each approach are outlined below.
Surgical Removal
Surgery for hidradenitis suppurativa typically involves wide excision of the affected skin through all layers [10,21,29]. Surgical treatment is considered the most definitive approach, and complete removal of the affected tissue may help minimize 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 lesions [21,29].
When the condition has spread over a wide area, skin flap procedures or skin grafting may be required.
In such cases, a referral to a university hospital or general hospital will be arranged. Our clinic is able to address cases involving partial skin removal.
When a long period has passed since onset and inflammation has spread beneath the skin, incomplete removal may lead to recurrence. In rare cases, skin cancer can develop at the site of hidradenitis suppurativa, making thorough excision of the affected area important.
By removing tissue with an adequate margin beyond the visible affected area, we aim for complete removal.
Medication
When surgical excision does not achieve the desired results or symptoms do not improve sufficiently, medical treatment may also be considered.
Treatment options include oral medications, topical treatments, and injectable therapies.
For example, adalimumab (Humira®) has been shown to reduce nodules and lesions 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 biologics, including infliximab, ustekinumab, and secukinumab, are also among the available treatment options [4,12].
Medical treatment can also help reduce pain associated with hidradenitis suppurativa.
However, it takes approximately three months for the therapeutic effects of Humira to become apparent. Humira is administered by injection into the abdomen, thigh, or back of the upper arm, allowing the medication to circulate throughout the body.
Self-injection is possible, which has the advantage of reducing the need for frequent clinic visits.
Please note that our clinic does not provide medication-based treatment for this condition. If this is your preference, we will arrange a referral 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 has reported that approximately 80% of patients experience difficulties in daily life, and approximately 60% report an impact on their ability to work [24,30].
The co-occurrence of depression and anxiety disorders is also significantly higher among patients compared to the general population, and psychological support is considered an important component of overall care [24].
Epidemiology and Prevalence of Hidradenitis Suppurativa
Hidradenitis suppurativa is a chronic inflammatory skin condition that is gaining increasing recognition worldwide, with prevalence varying by region [7,14,23].
Estimates suggest a prevalence of 0.05–4% in Western countries and approximately 0.05–0.1% in Japan, with women affected approximately 2–3 times more frequently than men [7,14].
Onset most commonly occurs after puberty, with an average age of onset of approximately 23 years [14]. Delayed diagnosis is a recognized issue, with international reports indicating an average of 7–10 years between symptom onset and confirmed diagnosis [27].
Pathophysiology and Molecular Mechanisms of Hidradenitis Suppurativa
The pathophysiology of hidradenitis suppurativa involves a complex inflammatory cascade in which both innate and adaptive immunity play roles [18,28].
Overproduction of inflammatory cytokines including TNF-α, IL-1β, IL-17, and IL-23 is a hallmark feature, and these cytokines are considered central to 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 pathophysiology [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 of Hidradenitis Suppurativa
Diagnosis of hidradenitis suppurativa is based on internationally recognized clinical criteria [6,20].
The primary diagnostic criteria require all three of the following to be present: ① typical skin lesions (deep, painful nodules); ② typical anatomical locations (axillae, groin, perianal area, inframammary region); and ③ a chronic, relapsing course [6].
Differential diagnoses include Crohn’s disease-associated pyoderma, folliculitis, epidermoid cysts, and cutaneous manifestations of Behçet’s disease. Detailed medical history and skin biopsy can be helpful in distinguishing between these conditions [20].
Treatment Guidelines and Scientific Evidence
Treatment of hidradenitis suppurativa is guided by the 2020 Clinical Practice Guidelines of the Japanese Dermatological Association [6].
For mild cases, topical treatments (topical antibiotics, combination therapy with clindamycin and rifampicin) are recommended, while systemic treatment (oral antibiotics, biologics) is recommended for moderate-to-severe cases [6].
Among biologics, the efficacy of adalimumab (an anti-TNF-α agent) has been demonstrated in multiple large-scale clinical trials, with significant improvement noted particularly in patients with Hurley Stage II–III disease [11].
Surgical treatment is considered the definitive therapeutic approach, with complete excision of the affected tissue offering the potential for long-term remission [21,29].
Hidradenitis Suppurativa (HS)
Internationally, the condition is referred to 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 section helps address your concerns and puts your mind at ease regarding treatment.
As a chronic progressive condition, hidradenitis suppurativa rarely resolves without treatment [8,20]. Without appropriate intervention, symptoms may worsen and lead to scarring and functional impairment [8]. Starting treatment as early as possible is important [6]. If the underlying contributing factors are addressed, there is a possibility that symptoms may improve without antibiotics.
In Japan, hidradenitis suppurativa is not designated as a specified intractable disease (shitei nanbyo) [26]. However, patients with severe cases may be eligible for medical expense assistance programs such as the High-Cost Medical Expense Benefit (Kōgaku Ryōyōhi Seido) [26]. In Western countries, it is recognized as a rare disease with established specialized treatment frameworks [8]. (Reference: Ministry of Health, Labour and Welfare Scientific Research Grants)
Hidradenitis suppurativa is not widely known by name, which means that depending on the specialty consulted, an accurate diagnosis may not always be reached.
While the condition does not qualify for the medical expense subsidies associated with designated intractable diseases, some financial assistance programs are available—for example, the High-Cost Medical Expense Benefit and supplementary benefit programs that provide reimbursement for out-of-pocket costs.
If you have questions about eligibility for these programs, please contact your health insurance association directly.
The condition tends to occur in areas rich in apocrine sweat glands, most commonly the axillae (85%), groin (70%), perianal area (45%), and inframammary region (35%) [15,23]. These locations are thought to be prone to follicular occlusion due to friction and a moist environment [9,17].
In terms of distribution by sex, hidradenitis suppurativa tends to develop in the armpits, buttocks, and groin in men, while in women it more commonly appears on the chest, armpits, buttocks, and inner thighs.
Because the condition can develop in areas that are difficult to see—such as the armpits or buttocks—it is easy to miss signs of progression.
As the condition advances, pus can accumulate in the swollen, inflamed bumps, and the affected area may gradually expand. In more severe cases, lesions beneath the skin may become interconnected, allowing inflammation to spread further.
Q. Can hidradenitis suppurativa resolve on its own?
As a chronic progressive condition, hidradenitis suppurativa rarely resolves without treatment [8,20]. Without appropriate intervention, symptoms may worsen and lead to scarring and functional impairment [8]. Starting treatment as early as possible is important [6]. If the underlying contributing factors are addressed, there is a possibility that symptoms may improve without antibiotics.
Q. Is hidradenitis suppurativa designated as an intractable disease in Japan?
In Japan, hidradenitis suppurativa is not designated as a specified intractable disease (shitei nanbyo) [26]. However, patients with severe cases may be eligible for medical expense assistance programs such as the High-Cost Medical Expense Benefit (Kōgaku Ryōyōhi Seido) [26]. In Western countries, it is recognized as a rare disease with established specialized treatment frameworks [8]. (Reference: Ministry of Health, Labour and Welfare Scientific Research Grants)
Hidradenitis suppurativa is not widely known by name, which means that depending on the specialty consulted, an accurate diagnosis may not always be reached.
While the condition does not qualify for the medical expense subsidies associated with designated intractable diseases, some financial assistance programs are available—for example, the High-Cost Medical Expense Benefit and supplementary benefit programs that provide reimbursement for out-of-pocket costs.
If you have questions about eligibility for these programs, please contact your health insurance association directly.
Q. Are there areas of the body where hidradenitis suppurativa is more likely to develop?
The condition tends to occur in areas rich in apocrine sweat glands, most commonly the axillae (85%), groin (70%), perianal area (45%), and inframammary region (35%) [15,23]. These locations are thought to be prone to follicular occlusion due to friction and a moist environment [9,17].
In terms of distribution by sex, hidradenitis suppurativa tends to develop in the armpits, buttocks, and groin in men, while in women it more commonly appears on the chest, armpits, buttocks, and inner thighs.
Because the condition can develop in areas that are difficult to see—such as the armpits or buttocks—it is easy to miss signs of progression.
As the condition advances, pus can accumulate in the swollen, inflamed bumps, and the affected area may gradually expand. In more severe cases, lesions beneath the skin may become interconnected, allowing inflammation to spread further.
Five Features of Our Clinic That Patients Appreciate
Team-Based Care Our clinic brings together specialists from multiple disciplines—including plastic surgery, dermatology, and orthopedic surgery—under the leadership of a board-certified plastic surgeon certified by the Japan Society of Plastic and Reconstructive Surgery.
Pain Management Our specialist physicians select the most appropriate surgical approach from a wide range of options, with the aim of minimizing discomfort throughout treatment.
Minimal Scarring We perform surgical excision with careful attention to the surrounding tissue, striving to minimize damage to the skin and achieve a clean result.
Same-Day Surgery Available — No Hospital Admission Required The process from consultation to surgery is smooth and efficient. Same-day, outpatient surgery is available.
Convenient Location Our clinics are located just a 3-minute walk from major transport hubs in central Tokyo, including JR Shinjuku South Exit and JR Shibuya Station.
Many patients visit our clinic with concerns like these.
Do any of these sound familiar?
- Experiencing pain or swelling caused by a skin lesion
- Having a lesion under the breast, on the buttocks, in the groin, or in the armpit
- Experiencing pain with pus draining from a pore
Our clinics are conveniently located just a short walk from major transport hubs, so if you are considering treatment for hidradenitis suppurativa, please do not hesitate to reach out to us.
References
- Japanese Dermatological Association, ed. Dermatology, 11th Edition. Bunkodo, 2018.
- 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.
- 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.
- 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.
- 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.
- Japanese Dermatological Association. Clinical Practice Guidelines for Hidradenitis Suppurativa, 2020 Edition. 2020.
- 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.
- Sabat R, Jemec GB, Matusiak Ł, et al. Hidradenitis suppurativa. Nat Rev Dis Primers. 2020;6(1):18.
- Prens E, Deckers I. Pathophysiology of hidradenitis suppurativa: An update. J Am Acad Dermatol. 2015;73(5 Suppl 1):S8-11.
- Japan Society of Plastic and Reconstructive Surgery, ed. Plastic Surgery, 4th Edition. Kokuseidodo, 2017.
- 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.
- 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.
- Harii K, Hashimoto K, eds. NEW Dermatology, 3rd Edition. Nakayama Shoten, 2018.
- 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.
- Zouboulia-Vafiadis I, Alexiou GA, Karagkiozi E, et al. Hidradenitis suppurativa: epidemiology, clinical presentation and pathogenesis. J Invest Dermatol. 2019;139(6):1254-1262.
- Editorial Committee of the Journal of the Japanese Dermatological Association. “Pathophysiology and Treatment of Hidradenitis Suppurativa.” Jpn J Dermatol. 2021;131(8):1567-1582.
- Kurzen H, Kurokawa I, Jemec GB, et al. What causes hidradenitis suppurativa? Exp Dermatol. 2008;17(5):455-456.
- 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.
- 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.
- Alikhan A, Lynch PJ, Eisen DB. Hidradenitis suppurativa: a comprehensive review. J Am Acad Dermatol. 2009;60(4):539-561.
- Robinson JK, Hanke CW, Siegel DM, et al. Surgery of the Skin: Procedural Dermatology, 3rd Edition. Elsevier, 2015.
- 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.
- 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.
- 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.
- Do You Know About Hidradenitis Suppurativa? AbbVie Inc. 2018.
- Ministry of Health, Labour and Welfare Scientific Research Grants. Research Group on Hereditary Intractable Skin Diseases. 2021.
- 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.
- 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.
- Japanese Society of Dermatologic Surgery, ed. Textbook of Dermatologic Surgery. Nankodo, 2019.
- 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.
