Acrodermatitis Continua of Hallopeau: Chronic Fingertip Pustules That Destroy Nails and Bone — A Dermatologist Explains How to Tell It From Infection

Acrodermatitis continua of Hallopeau (ACH) is a chronic inflammatory skin disease with recurrent sterile pustules on the tips of the fingers and toes. It belongs to the group of pustular psoriasis (pustular psoriasis). It is rare but important, because without the correct diagnosis and treatment, the inflammation gradually destroys the nails until they are lost permanently, and in long-standing cases it can spread to the bone at the fingertip and deform the finger.

The reason this disease is overlooked most often is that it looks very much like an infection of the nail or the skin around the nail. Many patients are therefore treated again and again with antibiotics or antifungal medicine without improvement, while the real disease keeps progressing. In this article, a dermatologist explains what the disease looks like, how it differs from an infection, and what treatment options you should know about.

What is Acrodermatitis Continua of Hallopeau?

ACH is a localized form of pustular psoriasis that affects the tips of the hands and feet. It is also known by other names, such as dermatitis repens or acrodermatitis perstans.

The key feature is small, sterile pustules on red, scaly skin at the fingertips, especially around and under the nail. These pustules burst, dry, form crusts, and then appear again in a chronic cycle. It often starts on a single finger (for example the thumb or big toe) and may slowly spread to neighboring fingers.

The word "sterile" is very important. Although you see pus, culture finds no bacteria or fungi. The pus here comes from neutrophils gathering together because of immune-driven inflammation, not from an infection.

What are the symptoms of ACH?

Common symptoms to watch for include:

• Small pustules on the fingertips on a red surface, usually around and under the nail, coming and going chronically.

• Red, peeling, cracked skin that is sometimes painful at the fingertips.

• Nail abnormalities — nails that flake, become pitted, thick or thin, or cloudy, up to the nail being lost completely (anonychia).

• Often starts on one finger and then gradually spreads. It may affect both hands or feet.

• In long-standing and severe cases, there may be tapering of the fingertip and a deformed finger because the bone at the fingertip has been destroyed.

The disease runs a chronic, relapsing course. It may settle for periods and then flare again, and in some patients it may later be associated with generalized pustular psoriasis.

Why ACH is dangerous — irreversible damage

Although it is a disease limited to the fingertips, what makes ACH need serious care is permanent destruction of structures.

• Nail destruction — continuous inflammation of the tissue that makes the nail (the nail matrix) deforms the nail and can cause it to be lost permanently.

• Erosion of the fingertip bone (osteolysis) — in long-standing cases that are not treated, the inflammation may reach the bone at the fingertip, making it thinner or shorter, so the finger becomes deformed and hard to use.

• Impact on daily life — painful fingertips, damaged nails, and deformed fingers greatly affect gripping, walking, and quality of life.

Once this damage has occurred, it usually cannot be reversed, which is why a correct diagnosis and starting treatment early are important.

What causes ACH, and who is at risk?

The true cause is still not clear, but it is believed to be due to an abnormality of the immune system, in the same group as pustular psoriasis. Related factors include:

• Part of the pustular psoriasis spectrum — some patients have, or have had, other forms of psoriasis as well.

• Genetic factors — in some patients, an association has been found with abnormalities in genes that control inflammation through the IL-36 signaling molecules.

• Triggers such as injury to the fingertip or a local infection may set off the disease in some people.

The disease is rare and is not contagious. The pustules you see do not spread infection to other people.

Where misdiagnosis is common — how to tell ACH from infection

This is the heart of this article, because ACH is often mistaken for an infection and treated the wrong way for a long time. A dermatologist tells it apart from similar-looking conditions as follows:

• Bacterial infection around the nail (bacterial paronychia) — usually sudden, with pain, red, hot swelling and true pus that grows bacteria in culture, and it responds to antibiotics. This differs from ACH, which is chronic, has sterile pus, and does not improve with antibiotics.

• Herpes of the fingertip (herpetic whitlow) — clusters of clear blisters with a burning pain, which usually clear on their own within 2–3 weeks and do not last for years.

• Nail fungus (onychomycosis) — thick, discolored nails with scale under the nail, but without recurrent sterile pustules, and fungus can be found on testing (read our article on "nail fungus" to compare the features).

• Itchy blistering rash of the hands (dyshidrotic eczema) — itchy clear blisters at the sides of the fingers and on the palms, not pustules that destroy the nail.

• Ordinary nail psoriasis — pitted nails or oil-drop marks under the nail, but without fingertip pustules that progressively destroy the nail as in ACH.

The most important clue is that if the fingertip has chronic, recurring pustules together with a nail that is gradually being destroyed, and does not respond to antibiotics or antifungal medicine, ACH should be considered and you should see a dermatologist for a clear diagnosis.

How is ACH diagnosed?

Diagnosis relies on assessment by a dermatologist together with further tests:

• Examination and history — chronic pustules at the fingertip and nail destruction.

• Culture — to confirm that it is sterile and to rule out a bacterial or fungal infection.

• Skin biopsy — shows pustules containing neutrophils in the epidermis, consistent with the pustular psoriasis group.

• X-ray (in some patients) — to assess whether the bone at the fingertip has been destroyed.

Treatment of ACH

ACH is a disease that is difficult to treat and often resistant to treatment, so a dermatologist needs to plan individual treatment and follow up closely. Approaches range from:

• Topical medicines — high-potency corticosteroids, vitamin D derivatives (calcipotriol), or calcineurin inhibitors for milder cases.

• Oral immune-modulating medicines — such as acitretin (a vitamin A derivative), methotrexate, or ciclosporin.

• Biologics — medicines that act specifically on the immune system, such as anti-TNF, IL-17, and IL-23 agents, including those targeting the IL-36 pathway, which plays a role in pustular psoriasis. They are an option that has given better results in many patients who did not respond to earlier medicines.

• Important caution — do not start and then suddenly stop oral steroids on your own, because this may trigger a severe flare or progression to generalized pustular psoriasis.

The goal of treatment is to keep the inflammation under control and prevent destruction of the nail and bone. Patients should continue treatment and follow up with their doctor regularly, and should not change or stop medicines by themselves.

Living with this chronic disease

Because ACH is a chronic disease that can recur, long-term care is important:

• Avoid injury to the fingertips and care for your hands and feet gently.

• Do not pick, scratch, or squeeze the pustules, because this may trigger inflammation and risk a secondary infection.

• Apply moisturizer to keep the skin around the nails moist and reduce cracking.

• Follow up with treatment regularly and tell your doctor when symptoms flare or when you have side effects from medicines.

When should you see a doctor?

You should see a dermatologist for a clear diagnosis if you have any of the following:

• Chronic, recurring pustules on the fingertips that do not improve even with antibiotics or antifungal medicine.

• Nails that are gradually becoming deformed, flaking, or falling off together with inflamed skin at the fingertip.

• Fingertips that are deformed or shorter than they used to be.

• Symptoms at the hands or feet that interfere with daily life and have not improved with self-treatment.

Seeing a dermatologist for differential diagnosis with a skin biopsy and culture helps you get the correct treatment early, which is the key to preserving the nails and the bone at the fingertip.

Frequently asked questions about Acrodermatitis Continua of Hallopeau

What is Acrodermatitis Continua of Hallopeau?

It is a rare chronic inflammatory skin disease with sterile pustules that appear repeatedly on the tips of the fingers and toes. It belongs to the pustular psoriasis group. If left untreated, it can permanently destroy the nails and the bone at the fingertip.

How is it different from nail fungus or an infected nail?

The difference is that ACH has chronic, recurring sterile pustules and does not respond to antifungal medicine or antibiotics, whereas an infection grows an organism in culture and usually improves when the organism is treated directly. A skin biopsy and culture by a doctor can tell them apart clearly.

Are ACH pustules contagious?

No. The pus comes from immune-driven inflammation, not from germs, so it does not spread to other people.

Can ACH be cured completely?

It is a chronic disease that is often resistant to treatment and can recur. At present there is not always a way to cure it completely, but modern medicines, especially biologics, help control the disease much better in many patients. The goal is to control the inflammation and prevent permanent damage.

Can ACH really cause permanent nail loss or damage to the finger bone?

Yes. If left untreated, continuous inflammation can deform the nail until it is lost permanently, and in long-standing cases it can reach the bone at the fingertip and deform it, so it is important to diagnose and treat early.

Is ACH related to psoriasis?

Yes. ACH is considered a localized form of pustular psoriasis. Some patients also have other forms of psoriasis, or it may later progress to generalized pustular psoriasis.

Written by Dr. Patara Voravutinon, Dermatologist · Last reviewed 2 August 2026

The information in this article is for basic understanding only and does not replace diagnosis and treatment by a doctor. Acrodermatitis continua of Hallopeau is a disease that is difficult to diagnose and treat and should be managed by a dermatologist. If you have symptoms or warning signs, please consult a doctor for an examination and a treatment plan suited to you.