What is pustular psoriasis? Definition, causes, symptoms and treatment

By Cristiano Antonino On May 10, 2023

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Pustular psoriasis is a type of psoriasis that causes pus-filled blisters on plaques, which are patches of scaly skin

Pustular psoriasis is common on the hands and feet, but can occur anywhere on the body

There is no specific cure for psoriasis, but treatment is available to help manage the symptoms.

This type of psoriasis causes reddish, scaly, pus-filled bumps.

Anyone with pus-filled bumps on a large part of the body needs immediate medical attention.

When widespread, pustular psoriasis can be life-threatening

Pus-filled bumps are called pustules.

They can form on the skin, inside the mouth or under a fingernail.

Approximately 24-48 hours after the pus-filled bumps appear, they coalesce and open.

When the pus dries up, the area turns red and glassy.

It often feels raw and tender.

New pustules may form on the red, glassy area.

These will also coalesce and open up.

Generalised pustular psoriasis (GPP)

This type of pustular psoriasis causes diffuse pus-filled bumps and requires immediate medical attention.

Symptoms of GPP include fever, chills, dehydration and an accelerated pulse.

Treatment for GPP in adults: a dermatologist may prescribe one of the following drugs to control psoriasis.

Oral retinoid

Infliximab: This is a biologic, which can rapidly reduce inflammation (and bumps). Since patients often respond quickly, some experts believe this may be the first choice when GPP is severe.

Since the above-mentioned drugs are powerful, they may not be suitable for some patients.

Another drug may then be chosen to keep psoriasis under control.

Possible psoriasis drugs that can be prescribed include:

Apremilast
Methotrexate
Cyclosporine
Another biologic, such as adalimumab or etanercept

To keep GPP under control, a dermatologist may prescribe two drugs.

Options include using etanercept (a biologic) and cyclosporine, infliximab (a biologic) and methotrexate or infliximab followed by etanercept.

Knowing how to prescribe these combinations requires in-depth expertise in the treatment of pustular psoriasis.

GPP in children: although rare, this condition can develop before someone turns 18. When it does, the first choices to treat it follow.

Cyclosporine: this may be the first choice because it works quickly. It usually takes two to four weeks to see an improvement.

Etanercept: this is a type of drug called biologic. It is used to treat severe plaque psoriasis in children aged between 4 and 17 years.

Some experts believe that this may be the first choice for treating a child with pustular psoriasis. It is usually administered twice a week for two months because it takes time to see improvement.

Methotrexate: a low dose can be given to a child as young as 2 years old. It often takes about two weeks to see an improvement in a child, but it can take longer.

Other drugs and treatments for psoriasis may also be an option, including phototherapy or another biologic.

Impetigo herpetiformis

Developing only in pregnant women during their last trimester, this type of pustular psoriasis starts with pus-filled bumps forming on the inner thighs and groin.

When the pustules unite and spread, the pus-filled protuberances cover a large and diffuse area.

Pus-filled bumps may develop inside the mouth and under the nails.

Since this condition is rare, it is not yet known whether it is actually a different type of pustular psoriasis.

While psoriasis can cover a wide area of your body, treatment options differ from those listed above for GPP.

For instance, pregnant women should not take an oral retinoid.

A treatment plan for treating impetigo herpetiformis often starts with psoriasis medication that is applied to the skin.

A dermatologist may prescribe:

A corticosteroid for the skin
Synthetic vitamin D

If a stronger treatment is needed to keep psoriasis under control, a dermatologist may prescribe:

Phototherapy

If you have severe or life-threatening psoriasis, your dermatologist may prescribe one of the following remedies to keep psoriasis under control:

Cyclosporine
A biologic

To reduce possible side effects, your dermatologist may prescribe more than one drug.

This may sound strange, but it can be an effective strategy when the doctor has experience in this area.

Palmopustular psoriasis

This type of pustular psoriasis causes pus-filled bumps to form only on the palms of the hands, the soles of the feet or both.

Often, one of the following is used to treat this type of pustular psoriasis:

Corticosteroid (apply to the skin)
Synthetic vitamin D (apply to the skin)
Phototherapy (light treatment)
Corticosteroids and salicylic acid (apply to the skin)

The above treatments are often effective for the treatment of mild diseases.

To strengthen the medication you apply to your skin, your dermatologist may tell you to apply the medication and then cover it with a gauze bandage or other dressing.

Acrodermatitis continua of Hallopeau

This type of pustular psoriasis is rare.

It causes pus-filled bumps on the fingertips, feet or both.

The disease may also develop under the nails.

New pus-filled bumps may often continue to appear on a finger or toe.

When this happens, new pustules may develop on more than one finger or toe.

In rare cases, pus-filled bumps may slowly spread to the arms or legs.

Anyone with pus-filled bumps on a large part of the skin needs immediate medical attention.

When widespread, pustular psoriasis can be life-threatening.

The first choice for treating this type of pustular psoriasis often includes the following.

Synthetic vitamin D combined with a strong corticosteroid: this combination is applied to the skin.

PUVA: this is a type of light treatment that involves taking a drug called psoralen before undergoing UVA light treatments on the affected skin.

While the above describes which treatment can be used for each type of pustular psoriasis, the treatment plan may include different drugs.

Your age, other medical conditions (if any) and general health also play a key role in determining which treatment is best for you.

Bibliographic references

Fitzpatrick JE. “Pustular eruptions.” In: Fitzpatrick JE and Aeling JL. Dermatology Secrets. Hanley & Belfus, Inc., Philadelphia, 1996:66-7.

Jeon C, Nakamura M, et al. “Generalized pustular psoriasis treated with apremilast in a patient with multiple medical comorbidities.” JAAD Case Rep. 2017;3(6): 495-7.

Robinson, A Van Voorhees AS, et al. “Treatment of pustular psoriasis: From the Medical Board of the National Psoriasis Foundation.” J Am Acad Dermatol 2012;67:279-88.

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