Hidradenitis Suppurativa: Symptoms, Types, Causes and Treatment

Hidradenitis suppurativa (HS) is a chronic, recurrent, and often painful inflammatory skin condition that profoundly impacts patients’ lives. Affecting areas of the body where skin rubs together—like the armpits, groin, and under the breasts—HS can lead to distressing symptoms, significant physical discomfort, and substantial psychosocial consequences. Despite being relatively common, HS is frequently misunderstood, underdiagnosed, and undertreated, making awareness and education about its symptoms, types, causes, and treatments crucial for both patients and healthcare professionals.

Symptoms of Hidradenitis Suppurativa

Living with HS means enduring a spectrum of symptoms that can fluctuate in intensity and profoundly affect daily life. Early recognition of these symptoms is vital for prompt diagnosis and management, as HS can cause not only physical discomfort but also significant emotional and social challenges.

Symptom	Description	Impact / Consequence	Source(s)
Pain	Persistent, often severe pain in affected areas	Most troublesome and quality-of-life limiting	1, 2, 4, 5
Nodules	Recurrent, tender lumps under the skin	May progress to abscesses and tunnels	2, 13, 14
Abscesses	Painful, swollen collections of pus	May rupture and drain	2, 14
Pruritus	Itching, usually mild-to-moderate	Common, can further affect quality of life	1, 2
Malodour	Unpleasant odor due to chronic drainage and infection	Social embarrassment	2, 4, 5
Exudation	Oozing or drainage from lesions or sinus tracts	Clothing stains, hygiene issues	1, 2, 5
Scarring	Thick, rope-like scars from healed lesions	Restricted movement, cosmetic concerns	2, 13, 14
Sinus tracts	Tunnels forming under the skin, connecting lesions	Recurrent infections, chronicity	2, 13, 14
Psychological	Depression, anxiety, low self-esteem, sexual dysfunction	Impaired mental health, social isolation	3, 4, 5

Table 1: Key Symptoms of Hidradenitis Suppurativa

Pain and Tenderness

Pain stands out as the most distressing symptom of HS. Patients often describe deep, throbbing pain that can make simple movements excruciating. This pain is not only physically limiting but also affects sleep, mood, and social interactions. Nearly 78% of patients report significant pain, which is more impactful on quality of life than the severity or extent of the skin disease itself 1, 4.

Skin Lesions: Nodules, Abscesses, and Sinus Tracts

HS begins with small, tender nodules under the skin. These can enlarge, become fluctuant, and evolve into abscesses—collections of pus that may burst and drain. Over time, repeated inflammation leads to the formation of sinus tracts, which are tunnels under the skin connecting different inflamed areas. Chronicity leads to scarring and permanent skin changes 2, 13, 14.

Pruritus, Malodour, and Exudation

While not as prominent as pain, pruritus (itching) is reported by up to 42% of patients and can further diminish quality of life 1, 2. Malodour from chronic drainage and infection is a frequent complaint that can contribute to social withdrawal, embarrassment, and even unemployment 2, 4, 5. Exudation (oozing) from the lesions often stains clothes and can make hygiene challenging.

Scarring and Restricted Movement

The healing process in HS can result in thick, rope-like scars and contractures, especially when lesions are located in flexural areas. This can limit mobility and lead to cosmetic concerns 2, 13, 14.

Psychological and Social Impact

Beyond the physical symptoms, HS has a profound effect on mental health. Rates of depression, anxiety, and even suicidal thoughts are significantly higher among patients with HS than in the general population or those with other skin diseases 3, 4, 5. Sexual dysfunction and impaired relationships are also commonly reported, especially when lesions occur in the genital area 4, 5.

Types of Hidradenitis Suppurativa

HS doesn’t look the same in everyone. Its presentation varies depending on severity, distribution, and underlying associations, making it essential to understand the different types and classifications to tailor effective treatment.

Type/Phenotype	Key Features	Clinical Relevance	Source(s)
Classic/Typical	Lesions in axillae, groin, perineal, inframammary	Most common presentation	2, 13, 14
Syndromic HS	Associated with genetic or autoinflammatory syndromes	May require specialized management	7, 8
Hurley Stages I-III	Severity-based classification	Guides treatment decisions	2, 13, 14
Follicular Phenotype	Prominent follicular occlusion, comedones	Overlaps with acne; may influence therapy	6, 7

Table 2: Types and Classifications of HS

Classic/Typical HS

This is the most frequently encountered form, marked by the presence of nodules, abscesses, and sinus tracts in the axillae, groin, perineal, and inframammary regions. The classic phenotype is characterized by recurrent lesions in these intertriginous (skin-fold) areas 2, 13, 14.

Syndromic HS

Some patients develop HS as part of rare genetic or autoinflammatory syndromes, including follicular occlusion triad/tetrad, PASH, PAPASH, SAPHO, and others. These forms may show earlier onset, more widespread involvement, and can be associated with systemic symptoms 7, 8. Recognizing syndromic HS is important, as these patients may need different diagnostic and therapeutic approaches.

Severity Grading: Hurley Staging

The Hurley staging system is widely used to classify HS severity:

• Stage I: Single or multiple abscesses, no sinus tracts/scarring.
• Stage II: Recurrent abscesses with sinus tracts and scarring, but with widely separated lesions.
• Stage III: Diffuse or near-diffuse involvement, interconnected sinus tracts, and abscesses across an entire area 2, 13, 14.

Treatment approaches are often guided by Hurley stage, with more aggressive therapies for higher stages.

Follicular Phenotype

HS is sometimes classified based on the prominence of follicular occlusion and comedones, which can overlap with acne vulgaris. This is especially relevant for early lesions and may influence treatment choices, such as the use of retinoids 6, 7.

Causes of Hidradenitis Suppurativa

Understanding what causes HS is complex, as the disease is multifactorial, involving genetic, immunological, environmental, and lifestyle factors. Despite ongoing research, many aspects of its pathogenesis remain unresolved.

Factor	Description/Role	Evidence/Notes	Source(s)
Follicular Occlusion	Blockage of hair follicles triggers inflammation	Central event in HS onset	6, 13, 14
Immune Dysregulation	Overactive innate and adaptive immune response	Inflammatory cytokines, NETs, B cells	8, 10, 11
Genetics	Family history and gene mutations (e.g. NCSTN, PSTPIP1)	Important in syndromic/early-onset cases	7, 8
Environmental	Smoking, obesity, friction	Major modifiable risk factors	2, 8, 13
Microbiome	Altered skin bacteria in lesions	May contribute to chronic inflammation	8
Hormonal	Onset after puberty; links to PCOS	Hormonal influence suspected	2, 12

Table 3: Major Causes and Risk Factors in HS

Follicular Occlusion: The Initiating Event

The primary event in HS appears to be the occlusion of the hair follicle, leading to rupture and subsequent inflammation in areas rich in apocrine glands. This blockage may result from abnormal keratinization and is followed by a cascade of local immune activation 6, 13, 14. The process triggers the development of nodules and abscesses.

Immune System Dysregulation

HS is increasingly recognized as an autoinflammatory disease. There is heightened activity of inflammatory pathways, particularly involving cytokines like TNF-α and interleukin-1β (IL-1β) 8, 10. Neutrophil extracellular traps (NETs), B cell activation, and a type I interferon signature have also been implicated, suggesting that both the innate and adaptive immune systems play roles in perpetuating tissue damage and chronicity 8, 10, 11.

Genetic and Syndromic Associations

A family history of HS is common, and certain genetic mutations (such as NCSTN and PSTPIP1) are directly linked to syndromic forms of the disease. These genetic associations are often seen in patients with early onset or those with co-existing autoinflammatory syndromes 7, 8.

Environmental and Lifestyle Factors

Smoking and obesity are repeatedly identified as the most significant modifiable risk factors. Smoking increases the risk of developing HS by up to twelvefold, while each unit increase in BMI also raises the risk 2, 8, 13. Mechanical friction, such as that caused by tight clothing, may contribute to lesion formation in susceptible individuals.

Microbiome and Hormonal Influences

Alterations in the skin microbiome of affected areas may perpetuate inflammation, although it is unclear if this is a cause or consequence of the disease 8. HS typically develops after puberty, and is more common in women, suggesting a hormonal component. It is also associated with conditions like polycystic ovary syndrome (PCOS) 2, 12.

Treatment of Hidradenitis Suppurativa

Managing HS is challenging and often requires a combination of medical, surgical, and lifestyle interventions. Treatment must be individualized based on disease severity, location, and patient preferences.

Treatment	Role/Indication	Key Points	Source(s)
Antibiotics	Mild-moderate disease; acute flares	Clindamycin + rifampicin; tetracyclines	13, 14, 15, 16
Biologics	Moderate-severe disease; refractory cases	Adalimumab, infliximab most studied	16, 17, 8, 13
Surgery	Chronic, severe, or localized lesions	Excision, deroofing, laser therapy	13, 15, 14, 16
Lifestyle	All patients	Weight loss, smoking cessation, hygiene	8, 13, 14
Pain Management	Symptom relief	Analgesics, local care	1, 4, 13
Adjuncts	Selected patients	Steroids, zinc, retinoids, hormonal therapy	15, 16, 14

Table 4: Main Treatment Approaches in HS

Antibiotics

Topical and oral antibiotics remain the backbone of initial therapy, especially in mild-to-moderate disease. Common regimens include topical clindamycin for localized disease and oral clindamycin plus rifampicin or tetracyclines for more extensive involvement 13, 14, 15, 16. These medications target both bacteria and the underlying inflammation.

Biologic and Immunomodulatory Therapies

For moderate to severe or refractory HS, biologic agents that inhibit inflammatory cytokines have become essential tools. Adalimumab (anti-TNF-α) is the only biologic approved specifically for HS and has shown significant benefit in reducing lesion counts and pain 16, 17, 8, 13. Infliximab and other agents targeting IL-1 and IL-12/23 pathways hold promise, particularly for patients not responding to traditional therapies 17, 8.

Surgical Approaches

Surgery is often required for chronic or severe HS, especially where there are sinus tracts or extensive scarring. Techniques range from limited local excision to wide excision and complex reconstructions. Carbon dioxide laser and tissue-sparing approaches are also used for selected cases 13, 15, 14, 16. Surgery may be combined with medical therapy for optimal results.

Lifestyle Modifications

Since obesity and smoking are key risk factors, all patients should be counseled on weight loss, smoking cessation, and proper hygiene. These measures can reduce the risk of new lesions and improve treatment outcomes 8, 13, 14.

Pain Management and Adjunctive Care

Given the prominence of pain, effective pain management is a priority. This may include analgesics, wound care, and treatment of superinfections. Intralesional or systemic steroids, zinc supplements, and retinoids may be considered in selected cases, especially for those not responding to first-line therapies 1, 4, 15, 16, 14.

Conclusion

Hidradenitis suppurativa is a complex, chronic inflammatory skin disease that goes beyond the skin to affect every aspect of a patient's life. Awareness of its symptoms, types, causes, and treatment options is crucial for timely diagnosis, effective management, and improved quality of life.

Key Takeaways:

• HS causes painful nodules, abscesses, sinus tracts, scarring, and significant psychosocial distress 1, 2, 4, 5.
• Types of HS vary by body location, severity (Hurley staging), and association with syndromic or genetic factors 2, 7, 8, 13.
• Central causes involve follicular occlusion, immune dysregulation, genetics, and modifiable lifestyle factors like smoking and obesity 6, 8, 13.
• Treatment is multidisciplinary and tailored to severity, ranging from antibiotics and biologics to surgery and lifestyle changes 13, 15, 16, 17.
• Effective management requires not only addressing skin lesions but also supporting psychological well-being and mitigating comorbid conditions 3, 4, 5.

By improving recognition and understanding of HS, we can offer affected individuals hope for better outcomes and a higher quality of life.