Hidradenitis Suppurativa, the Inflammatory Skin Disease with a Surprising Pathology


March 25, 2022

Hidradenitis suppurativa, or HS, is also called acne inversa. HS is a painful, debilitating, and chronic inflammatory skin disease1 that starts in hair follicles near sweat glands and is often mistaken for an infectious process. Painful lesions usually form in intertriginous areas (where skin rubs together) such as the groin, genitals, buttock, breast, and armpit regions.2 While these lesions may look like a simple boil, the characteristic features of HS include recurring painful boil-like nodules, abscesses that progress to purulent discharge, sinus tracts (tunnels), irreversible tissue destruction, and scar development.3–5 The recurrence and persistence of the lesions is also a key distinguishing feature of HS.6 Even within the same patient, activity and recurrence might happen consistently at the same site or vary between different areas of the body.7

While the pathology of HS is not fully understood, it’s considered to be a multifactorial disease involving dysregulated inflammation, a genetic predisposition, and environmental factors.8 The initial events are thought to be perifollicular inflammation followed by occlusion and dilation of the hair follicle and the release of pro-inflammatory cytokines. Inflammation causes the follicular wall to rupture, releasing intrafollicular debris into the dermis and furthering inflammation. This leads to the destruction of sebaceous and apocrine glands and ducts with the subsequent formation of tunnels, sinus tracts, and fistulas.9 These tunnels are filled with debris and fluid and extend throughout the skin to connect large cavities to surface lesions.6 Skin bacteria may be involved in activating and sustaining the skin’s innate immune response and inflammation.8

HS lesions are characterized by7:

A person's skin with HS
Reproduced with permission of Kang et al. (10)

A person's skin with HS

  • Open, double-headed comedones
  • Firm, painful papules and nodules
  • Pustules, fluctuant pseudocysts, and abscesses
  • Draining sinus tracts that link inflammatory lesions
  • Hypertrophic and atrophic scars

Living with HS is challenging for patients and impacts their lives in many ways.

We must make time to address this hidden disease. These are the patients that need our help but are often afraid, embarrassed, or too ashamed to ask for it.” Laura Bush, Dermatology PA‑C

The broad array of clinical presentations and the sites affected often lead to patients being misdiagnosed as having other conditions, such as an infection, prolonging the patient burden. In fact, the average delay in an accurate HS diagnosis is approximately 7 years from the onset of the first symptoms.2 The deep cysts and tunnels that develop beneath the skin are painful. As the body produces more and more scar tissue, the scars can thicken and may eventually restrict the person’s movement of their arms and other affected body parts.7,11 HS can have a profound impact on a person’s quality of life, damaging their body image and sexual health. The embarrassment and pain of these lesions can result in social withdrawal, depression, and even suicidal thoughts.12

According to Laura Bush, Dermatology PA-C, “when uncontrolled, HS affects the mind as much as the body, causing stress and anxiety. The stigma of HS can lead to avoidance of intimacy and relationships as it affects these sensitive areas of the body.”

Studies have also revealed that approximately 40% of people with HS are unable to work13 and that patients have active lesions for an average of 14 days per month.11 Notably, some studies report that HS has a significantly greater impact on a person’s quality of life than other dermatological diseases including psoriasis, atopic dermatitis, acne, and alopecia areata.11

One patient with HS noted that she has a “negative self image because of the skin lesions, and the bad odor which adds to the emotional impact of the disease.”

HS affects approximately 0.1% of the general US population, with women being affected (more than 3 times) more commonly than men.11,14 HS is most active between the ages of 20 and 40, and in women may resolve during menopause.11,15 HS is more prevalent in women of African descent or those with a family history of HS.4,5

Lifestyle risk factors such as obesity and smoking tobacco also increase the chances of developing HS.4,16,17 Obesity may contribute to HS because it’s often associated with metabolic syndrome. Moreover, increased skin-to-skin mechanical friction could facilitate follicular occlusion making it more likely that the inflamed follicle unit will rupture.17 Smoking is thought to escalate HS disease progression by activating immune cells and pro-inflammatory cytokines.16

A person's skin with HS
Reproduced with permission of Kang et al. (10)

HS requires a clinical diagnosis as there are no specific tests or biomarkers that can be used to diagnose this disorder, which often leads to misdiagnosis in the early stages of HS. Diagnosis primarily relies on the assessment of the patient looking for 3 key features: the type of lesions, location of the lesions, and whether the lesions are chronically recurring or persistent.4

Scarring is often present from past outbreaks. Lesions are typically found in intertriginous sites, such as the armpits and groin.4 Finally, the lesions must be persistent and recur regularly, with at least 2 recurrences within 6 months or the presence of persistent lesions for 3 or more months.6

“The impact of the delayed diagnosis of HS can not only lead to treatment difficulties but may even result in permanent scarring and disability.” Laura Bush, Dermatology PA-C

Health care providers should suspect HS in patients who present with recurrent abscesses in skin folds. Misdiagnosis is common, with patients reporting an average of 3 misdiagnoses before HS is identified; the most common misdiagnoses are boils, ingrown hair, and skin infections.18

Kristin Rygg, MPAS, Dermatology PA-C recommends that “when a patient has multiple scars or ‘abscesses’ in their axilla, groin, buttock, or breasts, the provider must have a high index of suspicion for HS and refer to dermatology immediately.

The average delay from symptom onset to HS diagnosis is approximately 7 years, in large part due to a lack of health care provider awareness in specialties outside of dermatology.1,2 This makes prompt recognition, diagnosis, and referral to a dermatology provider essential to prevent HS from progressing into a more debilitating stage of this disease with a severe impact on the patient’s physical and emotional health.

Sponsored by Novartis US Medical Affairs.



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18 Canadian Skin Patient Alliance. Scarred for Life: 2020 Update. A National Report of Patients’ Experiences Living with Hidradenitis Suppurativa. May 2020.