Acne Inversa (Hidradenitis Suppurativa): What It Is, Treatments, Causes and More

• Acne inversa is a chronic inflammatory disease that affects hair follicles 
• This condition causes lumps beneath the skin, which can enlarge to form painful abscesses and sinus tracts
• The exact causes are unknown, but smoking, obesity and genetics are known risk factors
• There is no cure for acne inversa, however there are treatment options to manage symptoms

Hidradenitis suppurativa, also known as acne inversa, is a chronic and potentially severe skin disease. It occurs when hair follicles become blocked near apocrine (sweat) glands and become inflamed, causing lumps to form beneath the skin. 

These lumps can range in size from small peas to large marbles. They may enlarge to form abscesses which can be unsightly, painful to the touch and foul-smelling when they rupture. Symptoms can become severe and lead to sinus tracts, severe pain and irreversible tissue destruction and disfiguring scar tissue.

Acne inversa is not curable and can be challenging to treat. A recent study found that this disease impairs quality of life more than any other skin condition. As such, it is important to begin treatment early to manage symptoms and halt the disease’s progress.

What Is Acne Inversa?

Hidradenitis suppurativa is a misnomer and was so-named based on the belief that this disease was related to the suppurative process of the sweat glands.  

However, this condition is brought on by the blocking of hair follicles, as is the case with acne. Acne inversa is therefore believed to be a more accurate name  – however, it affects skinfold areas and not the areas typically affected by acne.

Acne inversa is a chronic, inflammatory skin disease that affects the hair follicles around the sweat glands. Once hair follicles become blocked, sweat and bacteria build up inside and form lesions such as deep-seated nodules, abscesses and sinus tracts in skin folds. These eventually burst and spread to the surrounding area to form more lumps beneath the skin.

While the exact cause is not known, heredity and environmental factors have been identified as contributing factors. This disease is associated with multiple comorbidities including obesity, metabolic syndrome and  inflammatory bowel disease. 

Symptoms

Symptoms develop in skin folds (where skin rubs together) near sweat glands and worsen progressively over time. These symptoms include:

• Body odor due to bacteria or from lesions draining
• Burning and stinging
• Moderate to severe itching
• Painful lumps deep within the skin
• Sinus tracts – tunneling wounds beneath the skin containing blood and pus
• Weeping pustules

What areas are affected?

Acne inversa develops in skin folds and where sweat glands are present such as the armpits, under the breasts, inner thighs groin, anus and buttocks.

In addition to the high concentration of sweat glands and hair follicles, skin tends to rub together in these regions which causes irritation.

Stages of Acne Inversa

There are several systems used to classify acne inversa based on severity; the Hurley clinical staging system is the most widely used.

• Stage I – single or multiple abscess formation 
• Stage II – recurrent abscesses, formation of sinus tracts
• Stage III – widespread, interconnected sinus tracts and multiple abscesses

When left unchecked, symptoms can be so pronounced that it affects movement or the ability to sit comfortably due to inflammation, infection, extensive formation of scar tissue and severe pain. 

Studies show there is a great impact on quality of life as this disease affects the physical, emotional and social well-being of patients.

What Causes Acne Inversa?

While the exact cause is still unknown, science has determined that environmental and genetic factors are linked to this condition with the following risk factors identified:

Smoking is a well-established risk with up to 90% of people with acne inversa being active or past smokers. 

Obesity is a primary risk factor and disease severity is believed to be correlated with the degree of obesity. In one study researchers followed patients after bariatric surgery and found the number of patients reporting symptoms after weight loss decreased by 35%. In addition, the number of eruption sites were significantly reduced.

Genetics have been identified, as 30%–40% of patients report a family history of the disease.

This condition is not due to poor hygiene, shaving or deodorants.

Treatment Options for Acne Inversa

As acne inversa is not yet curable, treatment focuses on curbing bacterial growth, preventing new lesions from forming, treating existing lesions, and removing nodules and sinus tracts. Pain management is also important, as is support to manage depression or isolation – common outcomes of this disease. 

Over-the-Counter Treatments 

Over-the-counter (OTC) treatments may provide some relief from mild acne inversa symptoms.

Acne cleansers

Antimicrobial cleansers are recommended to reduce inflammation and dry out lesions with one of the following agents:

• Benzoyl peroxide – has powerful antibacterial properties
• Hydrogen peroxide – is an oxidizing agent that kills bacteria and dries up skin

While these cleansers are a standard treatment for acne inversa, patient adherence can be an  issue. One study found that patients were less likely to commit to daily use of antimicrobial cleaners due to difficulty in obtaining them in store and perceiving little benefit in using them.

Non-steroidal anti-inflammatory drugs

Non-steroidal anti-inflammatory drugs (NSAIDs), such as aspirin, ibuprofen or naproxen, can ease pain and reduce swelling. These medications can alleviate mild discomfort in the short term 

Topical retinoids

Topical retinoids have been used for decades to treat a range of skin conditions, as they have powerful anti-inflammatory properties to fight bacterial infections. Although the effects are modest, two particular types of retinoids, adapalene and tazarotene, have been proven to reduce the inflammation associated with acne inversa. 

Prescription Treatments

Prescription medications for wide-spread or moderate to severe symptoms can be used alone or in combination, or used alongside OTC medications and professional treatments. 

Antibiotics

Antibiotics play an important role in treating patients in Hurley Stages I and II as they work to   kill bacteria and fight infection. The most commonly used antibiotics are clindamycin and tetracycline – both first-line treatments

Clindamycin is a topical medication; tetracycline is an oral antibiotic that is recommended for patients with more widespread symptoms. 

Biologics

Biologics are administered by an intravenous infusion or injection. These treatments are for patients with severe symptoms, or for those that fail to respond to other treatments. These are powerful medications that alter the body’s immune system which results in symptom reduction. 

Two biologics currently used for this skin disease are adalimumab and infliximab. The former is FDA-approved for acne inversa but the latter has also shown results, both as a treatment and as maintenance therapy. 

Adalimumab has been shown to provide significant results for moderate to severe symptoms.  

Corticosteroids

Corticosteroids are potent medications that treat a wide range of conditions. In the case of acne inversa, they target inflammation and swelling, reduce pain and calm the immune system to effectively manage symptoms. 

These medications are typically prescribed for short-term use or rescue therapy for flare-ups for Hurley stage III patients. They are taken orally or by injection. Longer-term treatments apply intermittent low-dose therapy which has also been shown to be effective.

Surgery

While medications can halt the progression of this disease during the early stage of acne inversa, surgical interventions are required to remove sinus tracts, growths and extensive scarring when the disease advances. 

Surgical excision

Excision involves surgical removal of growths along with healthy tissue in the affected area. Skin grafts are required and can take months to heal. In one study review of patients who underwent excision, a complete recovery was observed in 60%, with partial recovery in 30% after a two-year period. 

STEEP

Skin-tissue-sparing excision with electrosurgical peeling (STEEP) takes a different approach in removing affected tissue. Rather than complete resection of the affected tissue, the STEEP method removes the lesional tissue and spares the surrounding healthy tissue. 

This method has shown promising outcomes for stage II and III patients with a statistically significant improvement in the quality of life of patients. 

Laser and light-based therapies 

Laser and light-based therapies are secondary treatments that are used alongside first-line treatments for better results.

They can reduce flare-ups by reducing bacteria growth and the number of hair follicles in the affected areas; they can also remove lesions. Carbon dioxide laser surgery is the most common laser treatment for acne inversa. 

One study of difficult-to-treat patients used both CO2 and Nd:YAG lasers. Researchers found these lasers were effective, minimally invasive and spared healthy tissue.

At-Home Treatments

Some at-home treatments and self-care practices can help reduce symptoms or minimize the risk of developing acne inversa. They are not meant to replace OTC and  professional medications, but to support these therapies. 

Healthy diet

As obesity is a known risk factor for acne inversa, maintaining a healthy weight can reduce active symptoms and prevent this disease from developing in the first place. Research indicates that a low-glycemic diet largely based on natural, whole foods and no dairy products may be the best approach. 

A Mediterranean diet can also be beneficial, as it is rich in anti-inflammatory foods that may prevent and reduce swelling including:

• Healthy fats
• Legumes
• Nuts and seeds
• Oily fish, such as salmon, mackerel, tuna and sardines
• Vegetables
• Whole grains

Honey 

Honey has antifungal, anti-inflammatory and antibacterial properties to speed up wound healing. Apply raw, unprocessed honey directly to the skin, allow it to rest for 15 minutes, then wash off.

Tea tree oil

Tea tree oil is an essential oil that has anti-inflammatory, antifungal, antiseptic and antimicrobial properties. These all work to address swelling and inflammation. To use, dilute 1–2 drops of tea tree oil with 12 drops of a carrier oil, such as almond or coconut oil and apply to the skin. 

Warm compress

A warm compress can reduce the swelling and inflammation of active lesions. Use a dry source of heat such as a heating pad or hot water bottle, apply the compress to your skin and allow it to rest for 10 minutes.  

Takeaway

Hidradenitis suppurativa is a chronic, severe skin disease characterized by painful, recurrent lumps most commonly under the breasts and armpits, around the groin and inner thighs, and anus and buttocks. These lumps eventually worsen, rupture and lead to sinus tracts and scarring.

Although the exact causes have not been established, smoking, obesity and genetics are all known risk factors. With this in mind, maintaining a healthy body weight and avoiding smoking can be positive actions for prevention and management of this disease.

While there is no cure, OTC and prescription medications, together with laser and light-based therapies can control the progression of the disease, manage symptoms and ease discomfort and pain. For severe and treatment-resistant cases, surgery is required to remove the affected tissue and thick scarring to improve quality of life.

If you suspect you may be developing early signs of acne inversa, see your care provider as early diagnosis and intervention is essential for best results.