Palmoplantar pustulosis: Current understanding of disease definition and pathomechanism

Associations of inflammatory cytokines with palmoplantar pustulosis: a bidirectional Mendelian randomization study

Background

Variations in circulatory cytokine levels have been observed during the onset and course of palmoplantar pustulosis (PPP); however, whether these changes are due to etiological or secondary factors is unclear. To clarify the causal relationship, we conducted a summarized-level bidirectional Mendelian randomization (MR) analysis in this study.

Methods

A FinnGen biobank genome-wide association study (GWAS) of 212,766 individuals (524 PPP patients and 212,242 controls) provided summary data for PPP, whereas genetic instrumental variables (IVs) linked to circulation cytokine levels were gathered from a GWAS of 14,824 European individuals. The inverse-variance weighted (IVW), weighted median (WME), simple mode, and MR-Egger methods were used to ascertain the changes in PPP pathogenic cytokine taxa. Sensitivity analysis, which included horizontal pleiotropy analysis, was then conducted. The reliability of the results was assessed using the leave-one-out approach and the MR Steiger test, which evaluated the strength of a causal relationship. To evaluate the reverse causality between PPP and circulating cytokine levels, a reverse MR analysis was carried out.

Results

Our study demonstrated positive associations between C-X-C motif chemokine 6 (CXCL6) and PPP (odds ratio, OR 1.257, 95%CI: 1.001-1.570, p = 0.043). C-C motif chemokine 19 (CCL19) and interleukin-6 (IL-6) were suggested to be protectively associated with the development of PPP (OR: 0.698,95% CI: 0.516-0.944, p = 0.020; OR: 0.656, 95%CI:0.437-0.985, p = 0.042). The results were steady after sensitivity and heterogeneity analyses.

Conclusion

At the genetic prediction level, we identified causally connected inflammation-related variables that contributed to the onset and development of PPP. The therapeutic options for some refractory PPP have expanded due to tailored cytokine therapy, generating fresh concepts for PPP diagnostics and mechanism investigation.

Retrospective study of the clinical significance of the neutrophil-to-lymphocyte ratio in 79 patients with palmoplantar pustulosis

Palmoplantar pustulosis (PPP) is a chronic relapsing inflammatory skin disease characterized by multiple vesicles, pustules, and erythematous plaques on the palms and soles. The exacerbation of PPP is strongly associated with focal infections, such as tonsillitis, dental infections, and sinusitis, in Japan. Recently, the neutrophil-to-lymphocyte ratio (NLR) has been widely used as a convenient and useful marker for clinical conditions and various diseases; however, an association between PPP and NLR has not yet been established. We retrospectively analyzed 79 patients with PPP from our hospital to evaluate the clinical significance of the NLR. The average NLR value in patients with PPP was significantly higher than that in healthy controls (2.30 ± 1.02 vs 1.69 ± 0.45, P < 0.001). A comparative analysis of patients with PPP with and without infectious complications showed that there was a statistical difference in the NLR between patients with PPP with and without focal infections, whereas no significant difference was found for metal allergy, smoking, and pustulotic arthro-osteitis. Multivariate analysis indicated that the NLR was significantly associated with focal infections (odds ratio = 18.38, 95% confidence interval 3.86-87.35, P < 0.001). The NLR was also significantly correlated with C-reactive protein levels (P = 0.013, r = 0.2857). Interestingly, after symptom improvement, the NLR significantly decreased from the baseline levels. Furthermore, statistical analysis using the Youden's index revealed that an NLR of 2.28 or higher was associated with the risk of any focal infections in patients with PPP. These results suggest that the NLR has potential applications as a biomarker of the presence of focal infections in patients with PPP.

Evaluation of hematological inflammatory parameters in patients with palmoplantar pustulosis

BACKGROUND

Palmoplantar pustulosis (PPP) is a chronic inflammatory disease of ill-defined etiopathology. Recent studies have proposed complete blood count-based hematological parameters, such as neutrophil/lymphocyte ratio (NLR) and platelet/lymphocyte ratio (PLR), as biomarkers to monitor disease status in many inflammatory diseases. This study aimed to analyze for the first time the clinical significance of hematological parameters, including NLR, monocyte/lymphocyte ratio (MLR), PLR, mean platelet volume (MPV), plateletcrit (PCT), and pan-immune-inflammation value (PIV) in PPP patients.

METHODS

We retrospectively investigated the clinical and laboratory data of 237 patients with PPP and 250 sex-age-matched healthy controls (HCs). Hematological parameters were compared between patients with PPP and HCs. The correlations between these parameters and disease severity, as well as treatment response, were analyzed.

RESULTS

NLR, MLR, MPV, PCT, and PIV values were significantly higher in PPP patients than in HCs. But in receiver-operating characteristic analyses, only monocyte count (Youden Index = 0.53), PCT (Youden Index = 0.65), and PIV (Youden Index = 0.52) performed relatively accurate distinguishment between moderate-to-severe cases and mild cases. PCT and PIV values were significantly correlated with disease severity. After treatment, both PIV and PCT values decreased significantly in the responder group but not in the non-responder group.

CONCLUSIONS

Hematological parameters altered significantly in PPP patients. PCT and PIV can be used as simple and inexpensive biomarkers for systemic inflammation in PPP patients.

Local injection of micro-dose guselkumab for palmoplantar pustulosis after partial failure of systemic ixekizumab treatment

We present a palmoplantar pustulosis case partially resistant to systemic IL-17A inhibitor (ixekizumab) treatment, and then receiving a local injection of 0.1 mL micro-dose (1 mg) IL-23 inhibitor (guselkumab) every 4 weeks for four times. The paradoxical lesion disappeared rapidly following local injection and there was no recurrence after 8 weeks of drug withdrawal. This is the first clinical report on the treatment of palmoplantar pustulosis by local injection of micro-dose guselkumab.

Treatment Patterns and Negative Health Outcomes in Palmoplantar Pustulosis Patients in Germany and the US

INTRODUCTION

Limited information exists on the epidemiology, treatment, and burden of palmoplantar pustulosis (PPP) and defining the optimal course of treatment remains challenging without approved targeted treatments in most countries. Here, we describe the clinical and demographic characteristics, treatments received, and negative health outcomes experienced among patients with PPP in the United States (US) and Germany.

METHODS

Retrospective cohort study between 2016 and 2021 using data from the US Merative™ MarketScan® Research Database and IQVIA™ German Disease Analyzer. Adult patients with PPP (ICD-10-CM L40.3) were followed from the date of their first qualifying PPP diagnosis and continued until the earlier of disenrollment or end date of database, during which treatment patterns and incidence rates of negative health outcomes were assessed. Treatment patterns included adherence, non-persistence, discontinuation, re-initiation, switching, and combination therapy.

RESULTS

The prevalence of PPP was 0.005% and 0.065% in the MarketScan database and German Disease Analyzer, respectively, with 1629 and 3866 patients meeting the inclusion criteria. Most patients were female (71.3%, 67.8%), with mean (SD) age of 54.1 (11.7) and 56.9 (14.3) years, respectively. One year post index, most patients received topical treatment (77.4%, 65.3%), but non-persistence and discontinuation were high. Oral and biologic treatments displayed higher levels of adherence, particularly apremilast and tofacitinib among oral treatments and TNF inhibitors and IL-23 inhibitors among biologics. Rates of negative health outcomes were higher among patients not receiving treatment post-index compared with those receiving treatment post-index across both databases, regardless of prior treatment history.

CONCLUSIONS

Establishing treatment guidelines remains an unmet need for patients with PPP and could improve quality of life by reducing the occurrence of negative health outcomes. The findings from this study may provide insight into the effectiveness of current treatment options for patients with PPP and can be leveraged to support the development of treatment guidelines.

Drug survival of biologic therapies for palmoplantar pustulosis: A nationwide study

BACKGROUND

Biological therapies have established efficacy in psoriasis vulgaris. However, palmoplantar pustulosis (PPP) has proven difficult to treat, and data on drug survival in these patients remain scarce.

OBJECTIVE

To investigate drug survival of biological treatments in a nationwide cohort of patients with PPP.

METHODS

We included all patients treated for PPP with a biologic from a prospective Danish nationwide registry between 2007 and 2019. Descriptive statistics were reported. Drug survival was calculated for all patients and specified for the most frequently used biologics. Drug survival was reported as median time to discontinuation. Kaplan-Meier plots were used to visualize drug survival. Trajectories of Dermatology Life Quality Index (DLQI) scores were plotted by interpolating between the different visits with a dermatologist for each treatment course.

RESULTS

We identified 85 individual patients who received biological therapy for PPP across 194 treatment courses during follow-up. Of the included treatment courses, 151 (77.8%) were discontinued. The most frequent cause of discontinuation was ineffective response to treatment (54.3%), while 18.5% of courses were discontinued due to adverse events. The median drug survival across all therapies for PPP was 9.3 (Inter quartile range (IQR), 3.9-25.6) months. Ustekinumab demonstrated the longest median time to discontinuation of 14.6 (IQR, 9.1-51.8) months. The proportion of bio-naive patients in treatment at 12 months were according to drug 47.9% for adalimumab, 64.3% for ustekinumab and 40.0% for secukinumab. For bio-experienced, it was 58.2% adalimumab, 54.5% for ustekinumab and 51.4% for secukinumab.

CONCLUSIONS

The treatment of PPP poses significant challenges, with limited drug survival observed across all therapies regardless of prior experience with biologics. Ustekinumab demonstrated the longest median drug survival. Notably, patients discontinuing therapy due to inefficacy exhibited higher DLQI scores, highlighting the importance of personalized treatment selection and timely consideration of therapy changes when inefficacy is established.

A fluorescence imaging technique suggests that sweat leakage in the epidermis contributes to the pathomechanism of palmoplantar pustulosis

Sweat is an essential protection system for the body, but its failure can result in pathologic conditions, including several skin diseases, such as palmoplantar pustulosis (PPP). As reduced intraepidermal E-cadherin expression in skin lesions was confirmed in PPP skin lesions, a role for interleukin (IL)-1-rich sweat in PPP has been proposed, and IL-1 has been implicated in the altered E-cadherin expression observed in both cultured keratinocytes and mice epidermis. For further investigation, live imaging of sweat perspiration on a mouse toe-pad under two-photon excitation microscopy was performed using a novel fluorescent dye cocktail (which we named JSAC). Finally, intraepidermal vesicle formation which is the main cause of PPP pathogenesis was successfully induced using our "LASER-snipe" technique with JSAC. "LASER-snipe" is a type of laser ablation technique that uses two-photon absorption of fluorescent material to destroy a few acrosyringium cells at a pinpoint location in three-dimensional space of living tissue to cause eccrine sweat leakage. These observatory techniques and this mouse model may be useful not only in live imaging for physiological phenomena in vivo such as PPP pathomechanism investigation, but also for the field of functional physiological morphology.

Photodynamic therapy for palmoplantar pustulosis: A case report

Palmoplantar pustulosis (PPP) is a chronic inflammatory skin disease characterised by sterile, relapsing pustules on erythematous, scaly backgrounds on the palms and soles. PPP impairs quality of life and is notoriously challenging to manage. Here, we presented the case of a 79-year-old male who suffered from recalcitrant PPP for 9 years and responded not well to halometasone, acitretin capsules and oral Chinese traditional medicine. The patient showed improvement with a great reduction of erythema, scales, pustules after 5 sessions of 5-aminolevulinic acid photodynamic therapy (ALA-PDT), suggesting that ALA-PDT could be a potentially safe and effective therapeutic option for PPP.

Successful treatment of pustulotic arthro-osteitis with amoxicillin: A case report and review of the literature

Palmoplantar pustulosis (PPP) is a chronic skin inflammatory disease characterized by sterile pustules on the palms and soles. Pustulotic arthro-osteitis (PAO) is a major comorbidity of PPP, frequently affecting the anterior chest wall. PPP and PAO are thought to be closely associated with focal infection. We report a female in her 40s who developed pustules on her palms and soles with tenderness of both sternoclavicular and left sacroiliac joints, which were not improved with non-steroidal anti-inflammatory drugs. Of note, she showed a great response to amoxicillin, resulting in the almost complete resolution of her skin lesions and arthralgia. We also reviewed previous reports to learn more about the potential therapeutic options of antibiotics for PAO.

The Epidemiology of Palmoplantar Pustulosis: An Analysis of Multiple Health Insurance Claims and Electronic Health Records Databases

BACKGROUND

Palmoplantar pustulosis (PPP) is a chronic inflammatory condition characterized by sterile pustules on the palms and soles. This study evaluated the epidemiology of PPP using claims and electronic health record (EHR) databases.

METHODS

Patients coded for PPP in the United States (US) and Japan from 2016 to 2020 were identified. Several PPP definitions were evaluated; the specific definition (≥ 2 visits coded for PPP, the second 31-730 days after diagnosis) was chosen for characterizing PPP epidemiology. Baseline characteristics and pre- and post-diagnosis treatments were summarized. Prevalence and incidence rates were analyzed by calendar year, sex, age, and database.

RESULTS

Prevalence and incidence of PPP were higher in Japan than the US. PPP prevalence increased over time. PPP occurred predominantly in adulthood and was more common among women. Features of metabolic syndromes, anxiety, and depression were more common among US PPP patients. Consistently high baseline use of anti-bacterial, anti-inflammatory/anti-rheumatic, and obstructive airway disease treatments was observed among PPP patients. Potential miscoding or misclassification of PPP limited this analysis. Prevalence estimates from databases may differ from field- and population-based approaches.

CONCLUSIONS

The burden of PPP was greater in Japan than in the US. Additional studies are needed to further elucidate PPP epidemiology worldwide.

Secukinumab-Induced Alopecia Areata Successfully Treated with Tofacitinib in a Patient with Palmoplantar Pustulosis

Secukinumab, a monoclonal antibody targeting interleukin-17 (IL-17), has exhibited encouraging results in the therapeutic management of palmoplantar pustulosis (PPP). The development of alopecia areata (AA) is closely related to IL-17, and IL-17A inhibitors were considered as a potential treatment modality. Therefore, the development of AA during secukinumab treatment for PPP is a rare adverse event that has been rarely reported worldwide. Here we report a 35-year-old female patient with PPP who developed AA after completing the induction period of secukinumab treatment. Discontinuing secukinumab and initiating treatment with tofacitinib resulted in a significant improvement in both PPP and AA. The emergence of AA in this patient can be attributed to paradoxical skin reactions associated with IL-17 inhibitors. Tofacitinib appears to alleviate biologic-induced AA during PPP syndrome treatment.

Spesolimab Efficacy and Safety in Patients with Moderate-to-Severe Palmoplantar Pustulosis: A Multicentre, Double-Blind, Randomised, Placebo-Controlled, Phase IIb, Dose-Finding Study

INTRODUCTION

We evaluated the anti-interleukin-36 receptor antibody spesolimab in patients with moderate-to-severe palmoplantar pustulosis (PPP).

METHODS

This phase IIb trial comprised a loading dose period to week (W) 4, then maintenance dosing to W52. Patients were randomised 2:1:1:1:2 to subcutaneous spesolimab 3000 mg to W4 then 600 mg every 4 weeks (q4w), spesolimab 3000 mg to W4 then 300 mg q4w, spesolimab 1500 mg to W4 then 600 mg q4w, spesolimab 1500 mg to W4, 300 mg q4w to W16 then 300 mg every 8 weeks (q8w), or placebo switching to spesolimab 600 mg q4w at W16. The primary efficacy endpoint was percentage change from baseline in Palmoplantar Pustular Area and Severity Index (PPP ASI) at W16. Secondary endpoints included a Palmoplantar Pustular Physician's Global Assessment (PPP PGA) score of 0/1. Safety (including adverse events [AEs], local tolerability) was assessed.

RESULTS

152 patients were treated. The primary endpoint was not met; mean differences for spesolimab versus placebo ranged from - 14.6% (95% confidence interval [CI]: - 31.5%, 2.2%) to - 5.3% (95% CI: - 19.1%, 8.6%); none reached significance. At W16, 23 (21.1%) and two (4.7%) patients in the combined spesolimab and placebo groups, respectively, achieved PPP PGA 0/1 (mean difference 16.4%; 95% CI: 3.8%, 25.7%), increasing to 59 (54.1%; combined spesolimab) and 12 (27.9%; placebo switch to spesolimab) patients at W52. Non-Asian patients had significant improvements in the primary endpoint (mean difference - 17.7%; nominal P = 0.0394) and PPP PGA 0/1 at W16 with spesolimab versus placebo. Rates of AEs and AE-related discontinuations were similar for spesolimab and placebo. Local tolerability events and injection-site reactions were more frequent with spesolimab than placebo.

CONCLUSION

The primary objective to demonstrate a non-flat dose-response relationship and proof-of-concept was not achieved; improvements with spesolimab occurred in secondary endpoints and in non-Asian patients, indicating potential modest benefits. Spesolimab was generally well tolerated (ClinicalTrials.gov NCT04015518).

Efficacy and safety of biological agents to treat patients with palmoplantar pustulosis: A systematic scoping review

BACKGROUND

Palmoplantar pustulosis (PPP), a chronic, recurrent pustular dermatosis associated with erythema, scales, and sterile pustules on the palms and soles, is commonly encountered in dermatology clinics. Whether PPP is a variant of psoriasis or a distinct condition is still debated. Although biological agents have been successfully used to treat moderate-to-severe psoriasis, existing literature on PPP is limited to case reports or small case series. The lack of well-documented clinical studies makes it difficult to select the ideal treatment for this condition. This review aims to discuss the efficacy and safety of biological agents in PPP treatment based on randomized controlled trials with the hope of inspiring dermatologist clinicians to propose new therapeutic approaches.

OBJECTIVES

This review aims to obtain high-level evidence to assess the efficacy and safety of biological agents in the treatment of patients with PPP.

METHODS

We searched the PubMed, Embase, and Cochrane databases up to May 18, 2023, for high-quality randomized controlled trials that reported at least one adverse event after PPP treatment with biological agents in patients > 18 years of age. RevMan 5.3 software was used for the meta-analysis.

RESULTS

Nine trials involving 799 participants were included in the analysis. We used ppPASI 75 as the primary efficacy measure. Anti-IL-23 and anti-IL-17A agents afforded 4.14-fold and 1.95-fold better outcomes than placebo treatment at weeks 16 and 12, respectively (P-value = 0.009, RR = 4.14, 95% confidence interval [CI; 1.43-11.98]; P-value = 0.02, RR = 1.95, 95% CI [1.11-3.42]). Moreover, anti-IL-23 agents at a dose of 100 mg were more effective than at 200 mg, indicating that 100 mg may be the best dose for anti-IL-23 agents. Next, we investigated the safety of biological agents for PPP treatment. The incidence of total adverse events (AEs) was 1.25 times higher for biological agents than for controls, indicating a good safety profile (RR = 1.25, P-value ＜ 0.00001, 95% CI [1.13, 1.37]). Additionally, we divided the common AEs into 16 categories and found that anti-IL-23 agents were more likely to induce infections. In conclusion, we evaluated safety and efficacy in a comprehensive comparison and found that anti-IL-23 agents conferred good clinical efficacy with a low incidence of AEs and could be recommended with caution.

LIMITATIONS

Only a few relevant, high-quality, randomized controlled trials were included in the study.

CONCLUSION

This study showed that biological agents can be used to treat patients with PPP with good efficacy; however, AEs cannot be ignored. Multi-center, high-quality clinical studies with large sample sizes are needed to further evaluate the effects and safety of biological agents in PPP treatment.

Efficacy and Safety of Apremilast for the Treatment of Japanese Patients with Palmoplantar Pustulosis: Results from a Phase 2, Randomized, Placebo-Controlled Study

BACKGROUND

Palmoplantar pustulosis (PPP) is a pruritic, painful, recurrent, and chronic dermatitis with limited therapeutic options.

OBJECTIVE

To evaluate the efficacy and safety of apremilast for the treatment of Japanese patients with PPP and inadequate response to topical treatment.

METHODS

This phase 2, randomized, double-blind, placebo-controlled study enrolled patients with Palmoplantar Pustulosis Area and Severity Index (PPPASI) total score ≥ 12 and moderate or severe pustules/vesicles on the palm or sole (PPPASI pustule/vesicle severity score ≥ 2) at screening and baseline with an inadequate response to topical treatment. Patients were randomized (1:1) to apremilast 30 mg twice daily or placebo for 16 weeks, followed by a 16-week extension phase during which all patients received apremilast. The primary endpoint was achievement of PPPASI-50 response (≥ 50% improvement from baseline in PPPASI). Key secondary endpoints included change from baseline in PPPASI total score, Palmoplantar Pustulosis Severity Index (PPSI), and patient's visual analog scale (VAS) for PPP symptoms (pruritus and discomfort/pain).

RESULTS

A total of 90 patients were randomized (apremilast: 46; placebo: 44). A significantly greater proportion of patients achieved PPPASI-50 at week 16 with apremilast versus placebo (P = 0.0003). Patients receiving apremilast showed greater improvement in PPPASI at week 16 versus placebo (nominal P = 0.0013), as well as PPSI and patient-reported pruritus and discomfort/pain (nominal P ≤ 0.001 for all). Improvements were sustained through week 32 with apremilast treatment. The most common treatment-emergent adverse events included diarrhea, abdominal discomfort, headache, and nausea.

CONCLUSIONS

Apremilast treatment demonstrated greater improvements in disease severity and patient-reported symptoms versus placebo at week 16 in Japanese patients with PPP with sustained improvements through week 32. No new safety signals were observed.

CLINICALTRIALS

GOV: NCT04057937.

Acrodermatitis continua of Hallopeau and generalised pustular psoriasis: Should they be the same or different entities?

Pustular psoriasis is characterised by eruptions of neutrophilic sterile pustules. The European Rare and Severe Psoriasis Expert Network consensus defines pustular psoriasis into three subtypes; generalised pustular psoriasis (GPP), palmoplantar pustulosis and acrodermatitis continua of Hallopeau (ACH). Mixed forms are categorised according to their predominant features. However, the Japanese Dermatological Association includes ACH under the diagnosis of GPP. This article aims to review the similarities and differences between ACH and GPP. Based on our review, interleukin (IL)-36RN mutations, the most frequent genetic findings in pustular psoriasis are found most commonly in GPP, followed by ACH. Genotypes of IL-36RN mutations among GPP patients and ACH patients are different between European and Asian ethnicities. IL-36 signalling pathway is the main mechanism. Metabolic diseases are common comorbidities and joint involvement can occur in 20.5%-36.4% of both conditions. Associated plaque psoriasis is more common in GPP than in ACH. Generally, ACH, even the generalised type, does not have systemic inflammation whereas GPP can occur with or without systemic inflammation. ACH can occur before, simultaneously, or after the development of GPP. However, response to treatment for GPP and ACH even in the same patients appear to be different. ACH seemed to be more recalcitrant to treatment than GPP but severe flare of GPP can lead to morbidity and mortality. Although GPP and ACH share genotypes and pathogenesis, we believe that ACH should be classified separately from GPP, and not under diagnosis of GPP. Future research is warranted to satisfactorily distinguish the two conditions.

Acrodermatitis continua of Hallopeau successfully treated with bimekizumab: A case report

Acrodermatitis continua of Hallopeau is a rare variant of localized pustular psoriasis characterized by the recurrent eruption of sterile pustules involving the distal portions of the fingers and toes that can lead to the destruction of the nail apparatus. Acrodermatitis continua of Hallopeau is a chronic, relapsing condition that is resistant to most topical and systemic psoriasis therapies, making it notoriously difficult to manage. Interleukin-36 and interleukin-17 are thought to play a pivotal role in the pathophysiology of pustular psoriasis, and evidence suggests that interleukin-17 inhibition can be an effective therapy for pustular psoriasis variants, including acrodermatitis continua of Hallopeau. Bimekizumab, a monoclonal antibody that inhibits the interleukin-17 pathway, may be a safe and effective treatment option for patients with acrodermatitis continua of Hallopeau. We present the first documented case of a patient with acrodermatitis continua of Hallopeau of the bilateral thumbnails who experienced an excellent response to bimekizumab treatment.

Targeting IL-36 in Inflammatory Skin Diseases

Interleukin (IL)-36 cytokines are members of the IL-1 superfamily of cytokines. IL-36 cytokines are composed of three agonists (IL-36α, IL-36β, and IL-36γ) and two antagonists (IL-36 receptor antagonist [IL36Ra] and IL-38). These work in innate and acquired immunity and are known to contribute to host defense and to the pathogenesis of autoinflammatory diseases, autoimmune diseases, and infectious diseases. In the skin, IL-36α and IL-36γ are mainly expressed by keratinocytes in the epidermis, although they are also produced by dendritic cells, macrophages, endothelial cells, and dermal fibroblasts. IL-36 cytokines participate in the first-line defense of the skin against various exogenous assaults. IL-36 cytokines play significant roles in the host defense system and in the regulation of inflammatory pathways in the skin, collaborating with other cytokines/chemokines and immune-related molecules. Thus, numerous studies have shown IL-36 cytokines to play important roles in the pathogenesis of various skin diseases. In this context, the clinical efficacy and safety profiles of anti-IL-36 agents such as spesolimab and imsidolimab have been evaluated in patients with generalized pustular psoriasis, palmoplantar pustulosis, hidradenitis suppurativa, acne/acneiform eruptions, ichthyoses, and atopic dermatitis. This article comprehensively summarizes the roles played by IL-36 cytokines in the pathogenesis and pathophysiology of various skin diseases and summarizes the current state of research on therapeutic agents that target IL-36 cytokine pathways.

Exceptional response of skin symptoms to secukinumab treatment in a patient with SAPHO syndrome: Case report and literature review

RATIONALE

SAPHO syndrome is a rare clinical entity characterized by a wide range of dermatological and musculoskeletal manifestations. Treatment strategies are not standardized. Palmoplantar pustulosis (PPP) is the most common rash in patients with SAPHO syndrome.

PATIENT CONCERNS

A 24-year-old Chinese woman with no relevant medical or familial history had a 1-year history of cutaneous lesions with PPP and pain in the sternoclavicular joint.

DIAGNOSIS

Based on the diagnostic criteria for SAPHO syndrome proposed by Nguyen et al in 2012, we diagnosed SAPHO syndrome with severe PPP as the predominant manifestation.

INTERVENTIONS

Due to the limited therapeutic efficacy of methotrexate and cyclosporin, we started therapy with subcutaneous secukinumab 150 mg weekly for the first month, then 150 mg monthly thereafter.

OUTCOMES

After 4 weeks of secukinumab administration, the patient showed significant remission of pustular skin lesions, with almost no joint pain and no adverse reaction. Complete remission of skin symptoms was achieved after 3 months. Joint pain and adverse events have not reoccurred in follow-up thus far.

CONCLUSIONS

In patients with SAPHO syndrome, we recommend personalized treatment, which may have excellent therapeutic efficacy in those with PPP or severe skin symptoms. Although data related to the use of IL-17 blockers for SAPHO syndrome are very limited, secukinumab provides a novel therapeutic option, especially for patients with PPP and severe skin lesions. Further prospective studies are needed to support our findings.

Beyond plaque psoriasis - pathogenesis and treatment of other psoriasis phenotypes

PURPOSE OF REVIEW

Psoriasis vulgaris is the commonest presentation of psoriatic disease, but morphologic variants such as pustular psoriasis (PP) and a closely related disease, pityriasis rubra pilaris (PRP), have been known for a long time, have been associated with rheumatologic manifestations indistinguishable from psoriatic arthritis (PsA) that may go unrecognized, and often represent a therapeutic conundrum. There is recent evidence that underlying genetic and pathogenetic differences may provide the basis for newer therapeutic approaches.

RECENT FINDINGS

This narrative review highlights the clinical, genetic and pathogenetic characteristics of PP and PRP, their association with PsA and recent developments in their treatment, especially with biologic agents targeting IL-36 and other cytokines of pathogenic relevance.

SUMMARY

The clinical manifestations of PP and PRP are less well known to rheumatologists than those of psoriasis, and recent advances in our insight on their pathogenesis may eventually overcome the therapeutic difficulties faced by dermatologists and rheumatologists in the management of these diseases and their rheumatologic manifestations.

Use of granulocyte and monocyte adsorption apheresis in dermatology (Review)

Adsorptive granulocyte and monocyte apheresis (GMA) is an extracorporeal treatment that selectively removes activated myeloid lineage leukocytes from peripheral blood. This technique consists of a column with cellulose acetate beads as absorptive leukocytapheresis carriers, and was initially used to treat ulcerative colitis. A literature search was conducted to extract recently published studies about the clinical efficacy of GMA in patients with different skin disorders, reporting information on demographics, clinical symptoms, treatment and clinical course. Dermatological diseases, in which GMA has been performed, include generalized pustular psoriasis, pyoderma gangrenosum, palmoplantar pustular psoriasis, Behcet's disease, Sweet's syndrome, adult-onset Still's disease, impetigo herpetiformis, reactive arthritis, acne and hidradenitis suppurativa syndrome, cutaneous allergic vasculitis and systemic lupus erythematosus. In most patients, GMA was started after the failure of conventional therapeutic options and it was helpful in the majority of cases. Based on the information summarized, GMA could be considered a valid non-pharmacological treatment option for patients with several dermatological conditions, which are difficult to treat with other pharmacological preparations.

Narrative Review of the Emerging Therapeutic Role of Brodalumab in Difficult-to-Treat Psoriasis

Psoriatic involvement in areas of the body such as nails, palms and soles (palmoplantar), and scalp is associated with dramatically negative effects on quality of life relative to involvement elsewhere in the body. Although numerous evidence-based studies demonstrate the efficacy of biologics for overall skin clearance in moderate-to-severe plaque psoriasis (including tumor necrosis factor α [TNFα] inhibitors and interleukin [IL]-17A, IL-12/IL-23, IL-23, IL-17F, and IL-17A/F inhibitors), large, randomized, placebo-controlled clinical studies of psoriasis with nail, palmoplantar, and scalp involvement are needed to better inform decision-making in clinical practice. Moreover, biologic failure caused by drug ineffectiveness is a common occurrence in patients who do not respond, lose response, or are intolerant to treatment. Brodalumab is a fully human IL-17 receptor A antagonist that demonstrates high rates of skin clearance among the latest generation of biologic therapies for treatment of moderate-to-severe psoriasis. This review summarizes current literature on the efficacy of brodalumab and other therapies in difficult-to-treat psoriasis including psoriasis in difficult-to-treat locations (such as psoriasis with nail, palmoplantar, or scalp involvement) and psoriasis in patients whose disease did not respond to other biologics.

Clinical characteristics of pustulotic arthro-osteitis in Korea

Pustulotic arthro-osteitis (PAO) has been studied primarily in Japan. However, there is a lack of research regarding its clinical features among large populations in other countries and it is often believed to be similar to psoriatic arthritis (PsA). Although the association between psoriasis (PsO) and palmoplantar pustulosis (PPP) is debatable, differences in the clinical characteristics between PsA and PAO might support the notion that PsO and PPP are distinct entities. This study aimed to investigate the clinical characteristics of PAO in Korean patients and to compare them with those of PsA. We retrospectively reviewed the medical records of patients diagnosed with PPP, PAO, and PsA. Among 266 patients with PPP, 13.2% had PAO. Unlike Japanese patients with PAO, Korean patients had a relatively lower involvement of the chest wall. PAO patients demonstrated lower age of onset, higher proportion of females, and higher severity of cutaneous eruptions compared to PPP patients without PAO, but the differences were not statistically significant. Female predominance was prominent in PAO compared to PsA. Cutaneous eruptions occurred earlier than joint symptoms in 83.5% of the patients with PsA and in 42.9% of the patients with PAO. PAO involved axial joints more frequently compared to PsA, especially the chest wall and spine. PsA mainly involved the peripheral joints, especially the metacarpophalangeal joints and distal interphalangeal joints of the hands and feet. In conclusion, PAO and PsA exhibited different demographics and locations of joint involvement, supporting the notion that PPP and PsO are separate disorders. Many PAO patients presented with joint symptoms before the appearance of skin eruptions, underlining the important role of dermatologists in recognizing PAO among PPP patients. Physicians should be aware of the characteristics of PAO while treating patients with PPP.

Risks of Comorbidities in Patients With Palmoplantar Pustulosis vs Patients With Psoriasis Vulgaris or Pompholyx in Korea

Importance

Palmoplantar pustulosis (PPP) has been reported to be accompanied by systemic conditions. However, the risks of comorbidities in patients with PPP have rarely been evaluated.

Objective

To assess the risks of comorbidities in patients with PPP compared with patients with psoriasis vulgaris or pompholyx.

Design, Setting, and Participants

This nationwide population-based cross-sectional study used data from the Korean National Health Insurance database and the National Health Screening Program collected from January 1, 2010, to December 31, 2019. Data were analyzed from July 1, 2020, to October 31, 2021. Korean patients diagnosed with PPP, psoriasis vulgaris, or pompholyx who visited a dermatologist between January 1, 2010, and December 31, 2019, were enrolled.

Exposures

Presence of PPP.

Main Outcomes and Measures

The risks of comorbidities among patients with PPP vs patients with psoriasis vulgaris or pompholyx were evaluated using a multivariable logistic regression model.

Results

A total of 37 399 patients with PPP (mean [SD] age, 48.98 [17.20] years; 51.7% female), 332 279 patients with psoriasis vulgaris (mean [SD] age, 47.29 [18.34] years; 58.7% male), and 365 415 patients with pompholyx (mean [SD] age, 40.92 [17.63] years; 57.4% female) were included in the analyses. Compared with patients with pompholyx, those with PPP had significantly higher risks of developing psoriasis vulgaris (adjusted odds ratio [aOR], 72.96; 95% CI, 68.19-78.05; P < .001), psoriatic arthritis (aOR, 8.06; 95% CI, 6.55-9.92; P < .001), ankylosing spondylitis (aOR, 1.91; 95% CI, 1.61-2.27; P < .001), type 1 diabetes (aOR, 1.33; 95% CI, 1.16-1.52; P < .001), type 2 diabetes (aOR, 1.33; 95% CI, 1.29-1.38; P < .001), Graves disease (aOR, 1.25; 95% CI, 1.11-1.42; P < .001), Crohn disease (aOR, 1.63; 95% CI, 1.11-2.40; P = .01), and vitiligo (aOR, 1.87; 95% CI, 1.65-2.12; P < .001) after adjusting for demographic covariates. The risks of ankylosing spondylitis (aOR, 1.37; 95% CI, 1.16-1.62; P < .001) and Graves disease (aOR, 1.40; 95% CI, 1.23-1.58; P < .001) were significantly higher among patients with PPP vs psoriasis vulgaris. However, the risks of psoriatic arthritis (aOR, 0.54; 95% CI, 0.47-0.63; P < .001), systemic lupus erythematosus (aOR, 0.67; 95% CI, 0.46-0.97; P = .04), Sjögren syndrome (aOR, 0.70; 95% CI, 0.50-0.96; P = .03), systemic sclerosis (aOR, 0.29; 95% CI, 0.11-0.77; P = .01), vitiligo (aOR, 0.53; 95% CI, 0.47-0.60; P < .001), and alopecia areata (aOR, 0.88; 95% CI, 0.81-0.95; P = .001) were significantly lower among those with PPP vs psoriasis vulgaris.

Conclusions and Relevance

The results of this cross-sectional study suggest that patients with PPP have an overlapping comorbidity profile with patients with psoriasis vulgaris but not patients with pompholyx. However, the risks of comorbidities among patients with PPP may be substantially different from those among patients with psoriasis vulgaris.

Diagnosis of Generalized Pustular Psoriasis

Generalized pustular psoriasis (GPP) is a severe rare skin disease characterized by widespread eruption of sterile superficial macroscopic pustules with or without systemic inflammation. Generalized pustular psoriasis flares may lead to life-threatening multiorgan complications, which highlights the need for rapid and accurate diagnosis. However, the rarity of the disease and its heterogeneous cutaneous and extracutaneous symptoms, and the resemblance of symptoms to other skin conditions, pose considerable challenges to the timely diagnosis and treatment of patients with GPP. Current laboratory tests used for GPP diagnosis are generally not GPP specific, and are mainly focused on the assessment of inflammatory markers and clinical and histopathologic features of GPP, and emerging genetic screening approaches. A differential diagnosis to distinguish GPP from other similar conditions requires careful assessment of the patient’s skin symptoms, potential disease triggers, medical history, histopathologic features, laboratory tests, and clinical disease course. The comprehensive interpretation of these assessments can be challenging owing to the lack of standardized global guidelines. While there is currently a lack of standardized international guidelines for the diagnosis of GPP, recent advances in our understanding of the genetics and pathogenesis of the disease have provided new opportunities to enhance diagnosis. In the future, defining specific GPP subtypes using genetic and histopathologic strategies will guide therapeutic decisions, allowing patients to achieve their treatment goals without delay. In this article, we provide an overview of the current diagnostic methods, differential diagnostic strategies, and future advances in the diagnosis of GPP, as well as features of GPP variants.

Principal Component Analysis to Differentiate Patients with Palmoplantar Pustulosis from Those with Palmoplantar Pustular Psoriasis

Background

Palmoplantar pustulosis (PPP) is initiated from the acrosyringium. However, it is unclear whether PPP should be considered a distinct entity or should be classified into the spectrum of pustular psoriasis, also known as palmoplantar pustular psoriasis (PPPP).

Objective

We evaluated the differences in immunohistochemical staining in patients with PPP to determine whether they can be classified into two groups based on psoriatic properties or acrosyringeal properties.

Methods

Nineteen punch biopsy specimens diagnosed with PPP were collected. Antibodies were chosen for identifying the acrosyringeal properties of α-3-nicotine acetylcholine receptors (α-3-nAChR), psoriatic properties of interleukin (IL)-23 and IL-36R, inflammatory cell properties of human cathelicidin antimicrobial peptide 18/LL-37, IL-8, lipocalin-2 (LCN2), and CD3. The degree of staining of the epidermis was evaluated using the ordinal scale (0~3). The principal component analysis was used to derive principal components (PCs) of common variation between the stains, and the two groups were divided using PCs and cluster analysis.

Results

Three main PCs explained 64% of the total variance in PPP. PC1 (pustular psoriasis properties) showed a higher correlation with IL-36R. PC2 (acrosyringeal/inflammatory properties) showed a higher correlation with α-3-nAChR, IL-8, LCN2, and CD3. PC3 (psoriasis properties) showed a higher correlation with IL-23. PC1 showed a statistically significant difference (p=0.0284) between the two groups. We identified three PCs associated with the pathomechanisms of PPP.

Conclusion

Although PC1 showed a statistically significant difference between the two groups, we did not identify differential protein expression related to the pathogenesis between PPP and PPPP.

Severe de novo pustular psoriasiform immune-related adverse event associated with nivolumab treatment for metastatic esophageal adenocarcinoma

Breakthrough targeted therapies have produced significant improvements in survival for cancer patients, but have a propensity to cause cutaneous immune-related adverse events (irAEs). Psoriasiform irAEs, representing about 4% of dermatologic toxicities associated with immune checkpoint inhibitor (ICI) therapy, are usually mild, occur in older patients and present as an exacerbation of existing psoriasis after several doses of ICI therapy. We report a case of a 58-year-old woman with metastatic esophageal adenocarcinoma and no prior history of psoriasis who developed a pustular psoriasiform irAE, beginning 3 days after initiation of nivolumab and progressing to confluent erythroderma with pustules over 2 weeks despite topical steroid use. She had concurrent acrodermatitis enteropathica, clinically diagnosed and confirmed with a low serum zinc level, that improved with supplementation. Her psoriasiform irAE was refractory to systemic steroids and acitretin, prompting discontinuation of nivolumab and treatment with ustekinumab and concomitant slow taper of acitretin and prednisone. Pustular psoriasiform irAE is a rare but severe dermatologic toxicity resulting from ICI therapy. Given the diverse morphologic types of cutaneous irAEs that can occur during ICI therapy, a clinical and histopathologic examination of dermatologic toxicities is critical to identify patients who may benefit from biologic therapy.

Pustular psoriasis as an autoinflammatory keratinization disease (AiKD): Genetic predisposing factors and promising therapeutic targets

Pustular psoriasis is a chronic inflammatory skin disease characterized by erythematous plaques with sterile pustules. It includes the distinct clinical entities generalized pustular psoriasis (GPP), acrodermatitis continua of Hallopeau (ACH) and palmoplantar pustular psoriasis (PPPP). Recently clarified pathomechanisms of pustular psoriasis indicate that hyperactivation of the skin innate immunity, including of the IL-1/IL-36 axis, plays an important role in the pathogenesis of pustular psoriasis. Autoinflammatory keratinization disease (AiKD) is the umbrella clinical entity for inflammatory keratinization disorders with genetic autoinflammatory pathomechanisms, and pustular psoriasis is a representative AiKD. To date, mutations/variants in five genes-IL36RN, CARD14, AP1S3, MPO and SERPINA3-have been reported to be genetic causative or predisposing factors for pustular psoriasis. The pathogenic mechanisms induced by the mutations/variants in these genes are all closely related to the excessive activation of skin innate immunity and autoinflammation. A number of biologics (e.g., tumor necrosis factor inhibitors, IL-17/IL-17 receptor inhibitors and IL-23 inhibitors) and granulocyte and monocyte adsorption apheresis are used to treat pustular psoriasis. Recently, based on novel information on the pathomechanisms of pustular psoriasis, which are mainly associated with autoinflammation, inhibitors of several pathogenic pathways, including of the IL-1, IL-36, IL-8 and granulocyte colony-stimulating factor signaling pathways, have been studied as emerging treatments.

Pustular Psoriasis: From Pathophysiology to Treatment

Pustular psoriasis (PP) is a clinicopathological entity encompassing different variants, i.e., acute generalized PP (GPP), PP of pregnancy (impetigo herpetiformis), annular (and circinate) PP, infantile/juvenile PP, palmoplantar PP/palmoplantar pustulosis, and acrodermatitis continua of Hallopeau (ACH), which have in common an eruption of superficial sterile pustules on an erythematous base. Unlike psoriasis vulgaris, in which a key role is played by the adaptive immune system and interleukin (IL)-17/IL-23 axis, PP seems to be characterized by an intense inflammatory response resulting from innate immunity hyperactivation, with prominent involvement of the IL-36 axis. Some nosological aspects of PP are still controversial and debated. Moreover, owing to the rarity and heterogeneity of PP forms, data on prognosis and therapeutic management are limited. Recent progresses in the identification of genetic mutations and immunological mechanisms have promoted a better understanding of PP pathogenesis and might have important consequences on diagnostic refinement and treatment. In this narrative review, current findings in the pathogenesis, classification, clinical features, and therapeutic management of PP are briefly discussed.

Pustular psoriasis: Molecular pathways and effects of spesolimab in generalized pustular psoriasis

BACKGROUND

The IL-36 pathway plays a key role in the pathogenesis of generalized pustular psoriasis (GPP). In a proof-of-concept clinical trial, treatment with spesolimab, an anti-IL-36 receptor antibody, resulted in rapid skin and pustular clearance in patients presenting with GPP flares.

OBJECTIVE

We sought to compare the molecular profiles of lesional and nonlesional skin from patients with GPP or palmoplantar pustulosis (PPP) with skin from healthy volunteers, and to investigate the molecular changes after spesolimab treatment in the skin and blood of patients with GPP flares.

METHODS

Pre- and post-treatment skin and blood samples were collected from patients with GPP who participated in a single-arm, phase I study (n = 7). Skin biopsies from patients with PPP (n = 8) and healthy volunteers (n = 16) were obtained for comparison at baseline. Biomarkers were assessed by RNA-sequencing, histopathology, and immunohistochemistry.

RESULTS

In GPP and PPP lesions, 1287 transcripts were commonly upregulated or downregulated. Selected transcripts from the IL-36 signaling pathway were upregulated in untreated GPP and PPP lesions. In patients with GPP, IL-36 pathway-related signatures, T_H1/T_H17 and innate inflammation signaling, neutrophilic mediators, and keratinocyte-driven inflammation pathways were downregulated by spesolimab as early as week 1. Spesolimab also decreased related serum biomarkers and cell populations in the skin lesions from patients with GPP, including CD3⁺ T, CD11c⁺, and IL-36γ⁺ cells and lipocalin-2-expressing cells.

CONCLUSIONS

In patients with GPP, spesolimab showed rapid modulation of commonly dysregulated molecular pathways in GPP and PPP, which may be associated with improved clinical outcomes.

Pustular Psoriasis: A Narrative Review of Recent Developments in Pathophysiology and Therapeutic Options

Pustular psoriasis is an unusual form of psoriasis that frequently presents clinical challenges for dermatologists. The condition presents with pustules on an erythematous background and has two distinct subtypes: localized disease on the palms and soles, called palmoplantar pustulosis (PPP), and generalized pustular psoriasis (GPP). The involvement of the fingers, toes, and nails is defined as a separate localized variant, acrodermatitis continua of Hallopeau, and is now thought to be a subset of PPP. The rarity of pustular psoriasis frequently makes the correct diagnosis problematic. In addition, treatment is limited by a relative lack of evidence-based therapeutic options. Current management is often based on existing therapies for standard plaque psoriasis. However, there remains a need for treatments with high, sustained efficacy and a rapid onset of action in pustular psoriasis. Recent advances in understanding of the pathogenesis of pustular psoriasis have provided insights into potential therapies. Treatment of pustular psoriasis is generally determined by the extent and severity of disease, and recent years have seen an increasing use of newer agents, including biologic therapies. Current classes of biologic therapies with US Food and Drug Administration and European Medicines Agency approval for treatment of moderate-to-severe plaque psoriasis in the USA (and elsewhere) include tumor necrosis factor alpha inhibitors (adalimumab, certolizumab pegol, etanercept, infliximab), interleukin (IL)-17 inhibitors (brodalumab, ixekizumab, secukinumab), an IL-12/23 inhibitor (ustekinumab), and IL-23 inhibitors (guselkumab, risankizumab, tildrakizumab). Recently, specific inhibitors of the IL-36 pathway have been evaluated in GPP and PPP, including spesolimab, an IL-36 receptor inhibitor which has shown promising results in GPP. The emerging drugs for pustular psoriasis offer the possibility of rapid and effective treatment with lower toxicities than existing therapies. Further research into agents acting on the IL-36 pathway and other targeted therapies has the potential to transform the future treatment of patients with pustular psoriasis. This article reviews the clinical features of PPP and GPP, and current understanding of the genetics and immunopathology of these conditions; it also provides an update on emerging treatments.

Pustular psoriasis is a skin condition where people develop small pus-filled blisters on their skin. Pustular psoriasis may affect certain areas of the body, such as the palms and/or the soles. This is called palmoplantar pustulosis (PPP for short). Another type of pustular psoriasis can affect most of the body called generalized pustular psoriasis (GPP for short). Not many people have PPP or GPP. Around 5–12 in every 10,000 people worldwide develop PPP. GPP is even rarer, affecting only 2–7 out of every 1 million people. In addition to being relatively uncommon, these conditions are challenging to treat. This article aims to help doctors who treat skin conditions (dermatologists) to identify and treat people with pustular psoriasis. Currently there is no standard treatment for GPP and PPP in the USA or Europe, but several medicines are approved for treatment of GPP in Japan. Doctors often use treatments that have been shown to work in plaque psoriasis, which is the most common type of psoriasis, to treat people with GPP and PPP. Traditional treatments for PPP and GPP are often not effective. Researchers are working on developing new effective treatments for pustular psoriasis that may work more rapidly and have fewer side effects. These are expected to be available in the next few years.

Single-center survey of biologic use for inflammatory skin diseases during the coronavirus disease 2019 pandemic

Coronavirus disease 2019 (COVID‐19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2). The ongoing COVID‐19 pandemic has affected both daily life and medical care; therefore, the aim of this study was to analyze the use of biologics for inflammatory skin diseases during the COVID‐19 pandemic in our hospital. The observation period was between 1 January 2020 and 23 February 2021. In this study, we enrolled 227 patients with psoriasis, six patients with palmoplantar pustulosis (PPP), 69 patients with atopic dermatitis (AD), and five patients with hidradenitis suppurativa (HS). Bioswitch was performed in 25 patients with psoriasis (11.0%). Biologics were discontinued in 14 patients with psoriasis (6.2%), 10 patients with AD (14.5%), and four patients with HS (80.0%); they were not discontinued in patients with PPP. The introduction of biologics was observed in 27 patients with psoriasis (11.9%), four patients with PPP (66.7%), 33 patients with AD (47.8%), and two patients with HS (40.0%). The use of telephone consultations was observed in four patients with psoriasis and two patients with AD. One patient, who received adalimumab for the treatment of psoriatic arthritis, suffered from COVID‐19 and recovered after a mild course. In conclusion, we report our experience regarding the use of biologic drugs for inflammatory skin diseases. The use of biologics seemed safe for use amidst COVID‐19 infection during the observation period; however, further observation on a larger number of patients is required to confirm the risks and benefits of biologic use in the COVID‐19 era.

Pustular Psoriasis and Acute Generalized Exanthematous Pustulosis

The similarity between pustular psoriasis (PP) and acute generalized exanthematous pustulosis (AGEP) poses problems in the diagnosis and treatment of these two conditions. Significant clinical and histopathologic overlap exists between PP and AGEP. PP is an inflammatory disorder that has numerous clinical subtypes, but all with sterile pustules composed of neutrophils. AGEP is a severe cutaneous adverse reaction that is also characterized by non-follicular sterile pustules. Clinical features that suggest a diagnosis of PP over AGEP include a history of psoriasis and the presence of scaling plaques. Histologically, eosinophilic spongiosis, vacuolar interface dermatitis, and dermal eosinophilia favor a diagnosis of AGEP over PP. Importantly, PP and AGEP vary in clinical course and treatment. PP treatment involves topical steroids, oral retinoids, and systemic immunosuppressants. Newer therapies targeting IL-36, IL-23, IL-1, and PDE-4 have been investigated. The removal of the offending agent is a crucial part of the treatment of AGEP.

Sustained efficacy and safety of guselkumab in patients with palmoplantar pustulosis through 1.5 years in a randomized phase 3 study

The safety and efficacy of guselkumab for palmoplantar pustulosis (PPP) have been established through week (W)52; however, no sufficient information is available beyond 1 year. This study was conducted to assess the efficacy and safety of guselkumab through W84, and to explore factors associated with the sustainability of its efficacy in Japanese PPP patients. Patients received guselkumab 100 or 200 mg at W0, W4, W12, and every 8 weeks (q8w) until W60, or placebo at W0, W4, and W12. At W16, patients receiving placebo were re‐randomized to receive guselkumab 100/200 mg at W16, W20, and q8w until W60. Efficacy end‐points included PPP Area and Severity Index (PPPASI), PPP Severity Index (PPSI), Physician’s Global Assessment scores, and patient reported outcomes (PRO) (Dermatology Life Quality Index, EuroQoL‐5 Dimensions, and 36‐item Short Form Health Survey). Post‐hoc comparison of patient characteristics was performed between PPPASI‐75/90 responders and non‐responders at W60, and sustained responders and non‐responders at W84. Safety was evaluated through W84. A total of 45, 43, 21, and 24 patients from the guselkumab 100 mg, guselkumab 200 mg, placebo→guselkumab 100 mg, and placebo→guselkumab 200 mg groups, respectively, completed the study through W84. Overall, the mean improvement in the guselkumab groups from baseline in the PPPASI and PPSI total scores at W84 was ~79% and ~66%, respectively. All PRO improved through W84. The proportion of responders through W60 was higher in patients who had not received prior phototherapy and non‐biologic systemic therapy for PPP. Non‐smokers and patients with no prior non‐biologic systemic treatment tended numerically towards sustained efficacy through W84. The majority of treatment‐emergent adverse events (TEAE) were mild to moderate (~88%) with low incidence of serious TEAE (7.6%). Overall, guselkumab showed sustained efficacy and safety with improvement in the health‐related quality of life through W84 in Japanese PPP patients.

Recent advances in palmoplantar pustulosis

Palmoplantar pustulosis (PPP) is a chronic inflammatory condition where crops of sterile pustules with erythematous keratotic lesions causing bleeding and pain appear on the palms and soles. Recently, the European Rare and Severe Expert Network considered PPP as a variant of pustular psoriasis with or without psoriasis vulgaris.

The prevalence of PPP varies from 0.050 to 0.12%. PPP occurs more frequently in women and the highest prevalence occurred between the ages of 50 and 69 years. Nail psoriasis seems to be frequent in PPP, ranging from 30 to 76%, and psoriatic arthritis in 8.6 to 26% of PPP patients.

Synovitis, acne, pustulosis, hyperostosis, osteitis (SAPHO) syndrome and pustulotic arthro-osteitis are considered PPP-associated disorders. PPP has been reported with other co-morbidities such as psychiatric disorders, thyroid-associated disease, altered calcium homeostasis, gluten sensitivity diabetes, obesity, and dyslipidemia, but larger studies are required to prove such associations. Environmental exacerbating factors might contribute to the onset or worsening of PPP such as cigarette smoking, stress, focal infections, metal allergies, and drug intake. Genetic predisposition plays an important role in PPP.

In PPP, both the innate and the adaptive immune systems are activated. The acrosyringeal expression of IL-17 has been demonstrated, indicating that the eccrine sweat gland is an active component of the skin barrier and an immune-competent structure. Increased levels of several inflammatory molecules, including IL-8, IL-1α, IL-1β, IL-17A, IL-17C, IL-17D, IL-17F, IL-22, IL-23A, and IL-23 receptor, have been detected in PPP biopsies. Increased serum levels of TNF-α, IL-17, IL-22, and IFN-γ have been detected in patients with PPP in comparison to healthy subjects, suggesting a similar inflammatory pattern to psoriasis vulgaris. Oral and tonsillar infections serve as trigger factors for PPP.

Long-term therapy is required for many patients, but high-quality data are limited, contributing to uncertainty about the ideal approach to treatment.