About Generalized Pustular Psoriasis
Ordinary psoriasis makes thick scaly plaques. Generalized pustular psoriasis is driven by a different part of the immune system and looks nothing like it. The pustules are sterile, meaning they contain white blood cells rather than bacteria, and they are not contagious. The whole body joins in: fever, a racing pulse, swollen skin that hurts to touch. Severe flares can lead to sepsis, dangerous drops in blood pressure, and kidney, lung or heart failure, which is why GPP is treated as a dermatologic emergency.
The engine behind it is a signaling pathway called interleukin-36, or IL-36. Think of IL-36 as an inflammation switch in the skin and a protein called IL-36Ra as the hand that turns it off. In many people with GPP the off switch is weak or missing because of changes in the gene IL36RN. Changes in a second gene, CARD14, do the opposite job and push the inflammation switch on, and a third gene, AP1S3, has also been linked to the disease. When the switch stays on, white blood cells flood the skin and form pustules. Many people with GPP have no detectable change in any of these genes, so the pathway can misfire for reasons that are still being worked out.
Diagnosis rests on the history of how the rash started, the appearance of the skin, and sometimes a skin biopsy. Blood tests alone cannot confirm it. Look-alike conditions include a drug reaction called AGEP and infected eczema, so a dermatologist with experience in pustular disease is worth seeking out.
Common Symptoms of Generalized Pustular Psoriasis
Recognizing the signs of Generalized Pustular Psoriasis early can lead to faster diagnosis and better outcomes. Symptoms may vary in severity from person to person. If you or a loved one are experiencing any of the following, consider speaking with a specialist.
- Crops of small pus-filled bumps (pustules) on red, tender skin, often across the trunk and limbs
- Flares that build within a week, with fever, chills, headache and exhaustion
- Burning, itching and pain in the affected skin
- Skin that dries, scales and peels as the pustules clear
- Joint pain, muscle weakness, nausea or diarrhea during a flare
- Flares that return, from several a year to one every few years, each lasting weeks to months
Who Generalized Pustular Psoriasis Affects
GPP can start at any age but most often appears between 40 and 60, and women are affected slightly more often than men. About 3% of people with psoriasis develop a pustular form, and around half of people with GPP also have plaque psoriasis. People with a change in the IL36RN gene tend to develop it earlier, sometimes in childhood. Flares are often set off by something: an infection, stress, pregnancy (usually in the third trimester), low calcium, certain medicines, and the withdrawal of steroid tablets or injections.
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