Overview of Pustular Psoriasis

3 Distinct Types With Different Symptoms and Treatments

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Annular pustular psoriasis

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Pustular psoriasis is one of several types of psoriasis. It differs from the "classic" form of the disease, known as plaque psoriasis, in which dry, red skin lesions (called plaques) are covered with silvery-white scales. With pustular psoriasis, the lesions form tender, pus-filled blisters known as pustules.

As with psoriasis itself, pustular psoriasis is categorized by type. Each of the three major types differs in its location, severity, and medical response. While accounting for less than one percent of psoriasis cases, pustular psoriasis is arguably more serious than any other form of the disease.

Symptoms

The symptoms of pustular psoriasis vary by the type. Generally speaking, the pustules appear as small white blisters similar to pimples but without the inflamed borders. They are usually closely clustered and set atop a patch a red, inflamed skin.

The pustules easily erupt and can be extremely itchy and painful. After breaking open, the pustules will form crusted, peeling lesions that heal slowly.

There are three types of pustular psoriasis:

  • Palmoplantar pustulosis (PPP) is the type that develops on small areas of the body, typically the palms of the hands or soles of the feet. PPP can be recurrent and is most common in people who smoke.
  • Acrodermatitis continua of Hallopeau (ACH) is characterized by small but extremely painful pustules that appear on the fingertips or toes and occasionally spread to the hands or soles. Nail and joint damage have been known to occur. The pain is often extreme enough to make walking or grasping objects difficult.
  • Von Zumbusch psoriasis, also known as generalized pustular psoriasis, is characterized by widespread itchy pustules. Other symptoms include fatigue, fever, chills, nausea, headache, muscle weakness, joint pain, and weight loss. The extreme peeling of skin can lead to rapid dehydration, tachycardia (rapid heart rate), and an increased risk of infection. If not properly treated Von Zumbusch psoriasis can become life-threatening.

Causes

All psoriatic diseases are characterized by an abnormal autoimmune response in which the immune system will suddenly and inexplicably attack normal skin cells. The ensuing inflammation causes the cells to multiply at an accelerated rate, causing them to build one on top of the other faster than they can be shed.

The cause of pustular psoriasis is poorly understood but is believed linked to a sudden, extreme burst of inflammation in transition between the upper layer of skin (epidermis) and the layer just below (dermis). In addition to triggering plaque, the inflammation will cause the rapid death of defensive white blood cells. This, paired with the accumulation of lymph fluid, causes the whitish fluid we recognize as pus.

Pustular psoriasis is associated with specific triggers that can give rise to acute episodes known as flares. In many cases, a person with plaque psoriasis will suddenly develop pustular psoriasis when confronted by these triggers.

Among the characteristic triggers:

  • Drug reactions are the most common cause, involving a wide range of common and common medications.
  • Abrupt discontinuation of prednisone can trigger a severe rebound of psoriasis symptom unless the prednisone dose is gradually tapered.
  • Strong topical medications have also been cited as causes, including psoriasis remedies like crude coal tar, anthralin, steroids under occlusion, and zinc pyrithione in shampoo.
  • Staphylococcal and streptococcal skin infections are also known to trigger pustular psoriasis.
  • Phototherapy use to treat psoriasis can on rare occasion trigger a severe flare. In addition to phototherapy, excessive sun exposure can act as a trigger.
  • Pregnancy has been known to incite a pustular outbreak, most often during the third trimester. This can lead to miscarriage or stillbirth.

Stress can also trigger recurrent flares or exacerbate an existing episode. Other episodes are idiopathic, meaning they are of no known origin.

Diagnosis

The diagnosis of pustular psoriasis will start with a physical exam and a review of your medical history. Because pustular psoriasis often occurs in people with a history of plaque psoriasis, these evaluations may be all that is needed to render a diagnosis.

In the end, there are no lab or imaging tests that can definitively diagnose psoriasis of any type. The diagnosis would be based largely on symptoms, individual risk factors, a review of potential triggers, and clinician experience.

With that being said, your doctor will make every effort to ascertain whether there are other explanations for the symptoms. This is referred to as the differential diagnosis.

One of the ways to do this is to send a pus sample to a pathologist for evaluation. Since pustular psoriasis is not caused by an infection, there should be no evidence of a bacteria, virus, or fungus unless the infection was secondary (meaning one that occurred as the result of the skin rupture).

Among some of the diseases included in the differential diagnoses are:

Treatment

The treatment of pustular psoriasis also varies by disease type. Both PPP and ACH are usually treated at home, while Von Zumbusch psoriasis almost invariably requires hospitalization.

Palmoplantar Pustular Psoriasis

Mild cases may only require topical treatments, such as hydrocortisone, coal tar, or salicylic acid creams or lotions. These may be applied in occlusion, meaning the skin is covered (say, with a sock or glove) so that the medication can be more readily absorbed.

Moderate to severe cases may require oral medications like Soriatane (acitretin), a retinoid drug which tempers the hyperproduction of skin cells, and disease-modifying antirheumatic drugs (DMARDs) like methotrexate or cyclosporine which temper the overall immune response.

Severe cases may be treated with an injection of methotrexate. Sometimes, one treatment is all that is needed to resolve the acute pustular symptoms.

Another option is psoralen ultraviolet light A (PUVA), a form of phototherapy in the drug psoralen sensitizes the skin to UV light. This may be used if the pustules are less responsive to treatment.

Acrodermatitis Continua

The treatment approach for ACH is similar to that of PPP, although, for reasons not entirely understood, people with ACH tend to be less responsive to such treatments. To bolster the effectiveness of ACH treatment, injectable biological drugs like Humira (adalimumab) and Enbrel (etanercept) are often combined with oral methotrexate.

While there are no guidelines to direct the appropriate treatment of ACH, numerous case studies, including one from the Mercer University School of Medicine in 2019, support the combination approach.

Von Zumbusch Psoriasis

When you have symptoms of generalized pustular psoriasis, it's critical to seek immediate care from a dermatologist. Most cases require hospitalization with intravenous (IV) fluids to prevent dehydration and IV antibiotics to prevent infections.

Generalized pustular psoriasis is treated by covering the skin in dressings soaked in a mixture of aluminum acetate and water (called Burow's solution). The preparation has astringent and antibacterial properties that can reduce swelling and aid with healing.

Oral retinoids are the most effective treatment for generalized pustular psoriasis and are considered first-line. Methotrexate or cyclosporine may be added in severe cases.

Prevention

Pustular psoriasis can be extremely distressing both physically and emotionally. There is little you can do to avoid getting pustular psoriasis since the causes are so varied and multidimensional. But, there are things you can do to reduce your risk:

  • Stop smoking. Smoking is one of the main risk factors for PPP but also contribute to ACH and Von Zumbusch. If you cannot stop on your own, ask your doctor about smoking cessation tools.
  • Lose weight. The increased accumulation of fat translates to increased levels of systemic inflammation. By eating right and exercising regularly, you can reduce the inflammatory burden on your body and, with it, the risk of flares.
  • Avoid excessive sun exposure. Limited sun exposure can reduce the hyperproduction of skin cells. But, overexposure can have the opposite effect and trigger an acute flare. Limit your daily exposure to 15 to 20 minutes, and wear plenty of sunscreen.
  • Manage your stress. Mind-body therapies like meditation, guided imagery, and progressive muscle relaxation (PMR) have their place in managing psoriasis symptoms and reducing the risk of flares.
  • Cut back on the alcohol. Like smoking, drinking excessively can increase your risk of flares. This is particularly true with non-light beer. If you cannot cut back entirely, limit yourself to no more than two to three drinks daily, replacing non-light beer with light beer or wine.
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