Generalized Pustular Psoriasis Treated With Risankizumab

To the Editor:

Generalized pustular psoriasis (GPP) is a rare but severe subtype of psoriasis that can present with systemic symptoms and organ failure, sometimes leading to hospitalization and even death.^1,2 Due to the rarity of this subtype and GPP being excluded from clinical trials for plaque psoriasis, there is limited information on the optimal treatment of this disease.

More than 20 systemic medications have been described in the literature for treating GPP, including systemic steroids, traditional immunosuppressants, retinoids, and biologics, which often are used in combination; none have been consistently effective.³ Among biologic therapies, the use of tumor necrosis factor α as well as IL-12/23 and IL-17 inhibitors has been reported, with the least amount of experience with IL-17 inhibitors.⁴

A 53-year-old Korean woman presented to the dermatology clinic for evaluation of a widespread painful rash involving the face, neck, torso, arms, and legs that had been treated intermittently with systemic steroids by her primary care physician for several months before presentation. She had no relevant medical or dermatologic history. She denied taking prescription or over-the-counter medications.

Physical examination revealed the patient was afebrile, but she reported general malaise and chills. She had widespread erythematous, annular, scaly plaques that coalesced into polycyclic plaques studded with nonfollicular-based pustules on the forehead, frontal hairline, neck, chest, abdomen, back, arms, and legs (Figure 1).

FIGURE 1. Initial presentation (day 0 [prior to treatment with risankizumab]). A and B, Scaly plaques coalesced into polycyclic plaques studded with nonfollicular-based pustules on the leg and neck, respectively.

Two 4-mm punch biopsies were performed for hematoxylin and eosin staining and direct immunofluorescence. Histopathologic analysis showed prominent subcorneal neutrophilic pustules and spongiform collections of neutrophils in the spinous layer without notable eosinophils (Figure 2). Direct immunofluorescence was negative.

FIGURE 2. Histopathologic findings at initial presentation consisted of prominent subcorneal neutrophilic pustules and spongiform collections of neutrophils in the spinous layer without notable eosinophils (H&E, original magnification ×20).

Based on the clinical history, physical examination, histopathology, and unremarkable drug history, a diagnosis of GPP was made. Initially, acitretin 25 mg/d was prescribed, but the patient was unable to start treatment because the cost of the drug was prohibitive. Her condition worsened, and she returned to the clinic 2 days later. Based on knowledge of an ongoing phase 3, open-label study for risankizumab in GPP, a sample of risankizumab 150 mg was administered subcutaneously in this patient. Three days later, most of the pustules on the upper half of the patient’s body had dried up and she began to desquamate from head to toe (Figure 3).The patient developed notable edema of the lower extremities, which required furosemide 20 mg/d andibuprofen 600 mg every 6 hours for symptom relief.

FIGURE 3. A and B, On Day 6— 3 days after treatment with subcutaneous risankizumab 150 mg— most of the pustules had already crusted over leading to generalized desquamation on the neck and back, respectively.

Ten days after the initial dose of risankizumab, the patient continued to steadily improve. All the pustules had dried up and she was already showing signs of re-epithelialization. Edema and pain also had notably improved. She received 2 additional samples of risankizumab 150 mg at weeks 4 and 16, at which point she was able to receive compassionate care through the drug manufacturer’s program. At follow-up 151 days after the initial dose of risankizumab, the patient’s skin was completely clear.