Oral alitretinoin treatment in patients with palmoplantar pustulosis inadequately responding to standard topical treatment: a randomized phase II study

Optimal treatments and outcome measures of palmoplantar pustulosis: A systematic review and network meta-analysis-based comparison of treatment efficacy

Few studies have made direct comparisons between treatments for palmoplantar pustulosis (PPP); therefore, it is difficult to select the best treatment for each patient. To determine the best therapy and to compare reported measures of efficacy in clinical trials of systemic treatments for PPP in this systematic review and network meta-analysis. Six databases were used to perform database search on 10 July 2022. Randomized controlled trials (RCTs) were identified through a systematic literature search. The titles and abstracts of articles were initially screened for inclusion by two authors independently using our predetermined criteria. The full texts of selected articles were then independently assessed for inclusion in a blinded fashion. Disagreement between the authors was resolved by consensus. Data were abstracted in duplicate. Random-effects model was accepted to perform network meta-analysis. Assessed Grading of Recommendations Assessment, Development and Evaluation certainty of evidence were performed according to the PRISMA guidelines. The analysis was completed in July 2022. The primary outcome was the change of PPP Area and Severity Index (PPPASI) from baseline and the secondary outcome was the achievement of PPPASI-50 response. Seven RCTs with 567 patients were included. Guselkumab 100 mg was the one with the highest probability of reaching the proposed outcomes (mean difference [MD], -8.00; 95% confidence interval [CI], 4.88-11.11), while the achievement of PPPASI-50 response did not show a significant difference (odds ratio [OR], 3.79; 95% CI, 0.51-28.37). Guselkumab 200 mg was next to 100 mg of reaching the proposed outcomes (MD, -4.71; 95% CI, 2.12-7.30), while the achievement of PPPASI-50 response did not show a significant difference (OR, 2.34; 95% CI, 0.48-11.43). Network meta-analysis showed guselkumab 100 mg was the treatment with the highest probability of reaching both PPPASI and PPPASI-50 outcomes. Absolute PPPASI may be more appropriate as an outcome than PPPASI-50.

Palmoplantar Pustulosis: A Systematic Review of Risk Factors and Therapies

Palmoplantar pustulosis (PPP) is a chronic, relapsing, inflammatory disease that can occur alone or in association with arthritis. There is still controversy about whether it should be separated from psoriasis or classified as pustular psoriasis. Furthermore, drug-induced paradoxical PPP is a special variant of PPP that differs from classic PPP in several ways. Treatment of PPP is still challenging, and there are a number of treatment-resistant cases. This review summarizes the risk factors for the development of PPP and the currently available treatment modalities. Female sex, smokers or ex-smokers, obesity, thyroid dysfunction, and treatment with a tumor necrosis factor (TNF)-α inhibitor have been identified as risk factors for the disease's development, severity, and course. Topical treatments and phototherapy are effective for some patients and are used as a first-line or adjuvant treatment modality. Conventional treatments including retinoids and fumaric acid show good effects and can increase the efficacy of treatment with psoralen + ultraviolet light therapy (PUVA). Ciclosporin is fast acting, but relapse mostly occurs immediately after cessation. TNF-α inhibitors are efficient, and an even better response can be achieved with IL-17 and IL-23 blockers as well as apremilast. The effect of Janus kinase inhibitors seems to be promising according to case reports, but further investigations with larger cohorts are needed.

An update on therapeutic options for palmoplantar pustulosis: a narrative review and expert recommendations

INTRODUCTION

Palmoplantar pustulosis (PPP) is a chronic inflammatory skin disease belonging to the localized form of pustular psoriasis. It is characterized by sterile pustule formation in palms and soles and a recurrent disease course. Although we have many treatments for PPP, there is no authoritative guidance.

AREAS COVERED

A thorough search of PubMed was conducted to identify studies in PPP from 1973 onwards, with additional references to specific articles. Any treatment methods were outcomes of interest, including topical treatment, systemic treatment, biologics, other targeted treatments, phototherapy, and tonsillectomy.

EXPERT OPINION

Topical corticosteroids are suggested as first-line therapy. Oral acitretin has become the most applied systemic retinoid recommended in PPP without joint involvement. For patients with arthritis, immunosuppressants like cyclosporin A and methotrexate are more recommended. UVA1, NB-UVB, and 308-nm excimer laser are effective phototherapy options. The combinations of topical or systemic agents and phototherapy may enhance the efficacy, particularly in recalcitrant cases. Secukinumab, ustekinumab, and apremilast are the most investigated targeted therapies. However, heterogeneous reported outcomes in clinical trials provided low-to-moderate quality evidence of their efficacy. Future studies are required to address these evidence gaps. We suggest managing PPP based on the acute phase, maintenance phase, and comorbidities.

Involvement of Molecular Mechanisms between T/B Cells and IL-23: From Palmoplantar Pustulosis to Autoimmune Diseases

Palmoplantar pustulosis (PPP) is a disease that causes recurrent blisters and aseptic pustules on the palms and soles. It has been suggested that both innate and acquired immunity are involved. In particular, based on the tonsils and basic experiments, it has been assumed that T and B cells are involved in its pathogenesis. In addition, the results of clinical trials have suggested that IL-23 is closely related to the pathogenesis. This review describes PPP and the genetic background, the factors involved in the onset and exacerbation of disease and its relation to the molecular mechanism. In addition, we describe the usefulness of biological therapy and its implications in relation to the importance in pathology, the pathogenesis of PPP, the importance of the role of the IL-23-Th17 axis and IL-36 in PPP. Furthermore, we describe an animal experimental model of PPP, the efficacy and mechanism of action of guselkumab, an anti-IL-23 antibody, the latest research, and finally the possibility for it to be effective for other autoimmune diseases.

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.

Interventions for chronic palmoplantar pustulosis: abridged Cochrane systematic review and GRADE assessments

BACKGROUND

Palmoplantar pustulosis (PPP) is a chronic inflammatory disease in which sterile and relapsing pustules appear on the palms and soles.

OBJECTIVES

To assess the effects of interventions for chronic PPP to induce and maintain complete remission.

METHODS

We searched for randomized controlled trials (RCTs), including people with PPP or chronic palmoplantar pustular psoriasis, in the Cochrane Skin Specialised Register, CENTRAL, MEDLINE, Embase, LILACS and eight trials registers up to July 2020. Study selection, data extraction and risk-of-bias assessment were carried out independently by two review authors. Certainty of evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) method.

RESULTS

We included 37 RCTs (1663 participants, 76% women, mean age 50 years). Mean treatment duration was 11 weeks. Topical vitamin D derivative may be more effective than placebo in achieving clearance [risk ratio (RR) 7·83, 95% confidence interval (CI) 1·85-33·12; low-certainty evidence from two trials]. Concerning biological therapies, there was little or no difference between etanercept and placebo in achieving clearance (low-certainty evidence from one trial), ustekinumab is less effective than placebo in reducing severity (low-certainty evidence from one trial), and guselkumab (RR 2·88, 95% CI 1·24-6·69) and secukinumab (RR 1·55, 95% CI 1·02-2·35) are probably better in reducing disease severity (moderate-certainty evidence from two and one trial(s), respectively) but may cause more serious adverse events than placebo.

CONCLUSIONS

Evidence is lacking for or against major chronic PPP treatments. Risk of bias and imprecision limit our confidence in the results.

Efficacy of Systemic Treatments of Nail Psoriasis: A Systemic Literature Review and Meta-Analysis

Importance: Nail involvement is a common condition in patients with psoriasis. The treatment of nail psoriasis is considered challenging and is often left untreated by physicians. Objective: To assess the efficacy of current systemic treatments on nail psoriasis. Data Sources: PubMed, EMBASE, and Cochrane Central Register of Controlled Trials (CENTRAL) were searched for relevant articles from inception to September 1, 2020. Included articles were restricted to English language and human studies. Study Selection: This was a systematic literature review with meta-analysis. Thirty-five random control trials that evaluated systemic therapies for nail psoriasis were selected in the systemic review. Among them, we retained 14 trials for meta-analysis. Data Extraction and Synthesis: This study was conducted in accordance with the preferred reporting items for systematic review and meta-analysis protocols (PRISMA-P) 2015 statement. All steps were performed by two independent investigators, and any disagreements were resolved by a third investigator. Meta-analysis of aggregated study data was conducted to assess therapeutic efficacy. The use of random-effects model was based on high heterogeneity as a variable endpoint in different studies. Main Outcomes and Measures: Therapeutic effects on nail psoriasis were expressed in terms of effect sizes with 95% CIs. Results: We included 35 random control trials (RCTs) in this systemic review. At baseline, a high prevalence (62.1%) of nail psoriasis was confirmed. The meta-analysis included 14 trials highlighting that biologic and small-molecule therapies were effective in treating nail psoriasis with variable effect size magnitudes [-0.89 (-1.10, -0.68), I ² = 84%]. In particular, tofacitinib and ixekizumab showed the most significant scale of effect size magnitudes in treating nail psoriasis (-1.08 points and -0.93 points, respectively). We also found that a higher dose of tofacitinib and ixekizumab had similar effectiveness, and anti-IL-17 agents seem to be superior in effectiveness compared to anti-TNF-α therapies in the treatment of nail psoriasis. However, these results must be displayed carefully as variable endpoints in different studies. Conclusions and Relevance: This study provides a comprehensive overview of systemic treatments for nail psoriasis. For patients with psoriatic nail damage who are candidates of systemic therapies, the priority should be given to administering biologic and small-molecule therapies, especially anti-IL-17 drugs.

Immediate response to apremilast in patients with palmoplantar pustulosis: a retrospective pilot study

Background

Recent case reports have shown the efficacy of apremilast for the treatment of palmoplantar pustulosis (PPP). However, no study has statistically analyzed the clinical efficacy of oral apremilast in patients with PPP.

Objectives

To evaluate the effectiveness of apremilast, a phosphodiesterase 4 inhibitor, for PPP.

Materials and Methods

Among 13 patients who were diagnosed with PPP, 10 patients with PPP with either palmoplantar pustules (>1 mm diameter) or sternoclavicular joint pain were retrospectively analyzed.

Results

Palmoplantar Pustulosis Area and Severity Index (mean ± SD: baseline, 13.4 ± 9.5 vs. after treatment, 5.1 ± 5.6; P = 0.013) and the number of pustules measuring > 1 mm in diameter (3.9 ± 3.9 vs. 1.3 ± 1.9; P = 0.029) significantly improved in 2 (±1) weeks. Moreover, the Dermatology Life Quality Index (9.7 ± 7.0 vs. 3.3 ± 3.6; P = 0.009) and palmoplantar itching (visual analog scale [VAS] score) (5.6 ± 3.5 vs. 2.1 ± 2.2; P = 0.026) significantly improved in 2 weeks, whereas VAS scores of palmoplantar pain (4.8 ± 4.4 vs. 1.1 ± 2.4; P = 0.081) and sternoclavicular joint pain (3.2 ± 3.8 vs. 2.0 ± 2.6; P = 0.194) did not significantly improve. Diarrhea was observed in 60.0% of our patients.

Conclusion

Our study demonstrated that apremilast can effectively treat cutaneous manifestations and arthralgia in Japanese patients with PPP who had apparent pustules and/or clavicular‐sternocostal arthralgia. Owing to the retrospective design of the study and a small sample size, placebo‐controlled clinical trials with a larger number of patients are warranted to confirm the efficacy of apremilast for treatment of PPP.

Oral Alitretinoin for Patients with Refractory Prurigo

Background: prurigo is a chronic skin disorder associated with a history of chronic pruritus. The pathogenesis of prurigo is largely unknown and the treatment of prurigo is unsatisfactory and challenging. Conventional systemic treatments may be beneficial; however, their possible side effects and possible transient efficacy is still a problem. We aimed to present the clinical course and effect of treatment with alitretinoin on patients with prurigo nodularis initially treated with conventional treatments like oral antihistamine, cyclosporine, and phototherapy. Methods: all the patients had prurigo nodularis refractory to conventional treatment. Their medical records included demographic features, past medical history, duration of disease, and treatment modalities; and the clinical courses of the patients were reviewed for this retrospective study. We evaluated patient pruritus and skin lesions for the duration. Results: we present reports involving 10 patients with refractory prurigo. All the patients in our cases were treated with oral alitretinoin after previous treatments and reported the improvement of skin lesions and pruritus within 2 weeks to 3 months. Conclusions: we suggest that oral alitretinoin may be an effective and well tolerated treatment option for patients with intractable prurigo. Further clinical studies are warranted to confirm the long-lasting efficacy and safety of alitretinoin for treating patients with prurigo.

Diagnosis, Screening and Treatment of Patients with Palmoplantar Pustulosis (PPP): A Review of Current Practices and Recommendations

Palmoplantar pustulosis (PPP) is a rare, chronic, recurrent inflammatory disease that affects the palms and/or the soles with sterile, erupting pustules, which are debilitating and usually resistant to treatment. It has genetic, histopathologic and clinical features that are not present in psoriasis; thus, it can be classified as a variant of psoriasis or as a separate entity. Smoking and upper respiratory infections have been suggested as main triggers of PPP. PPP is a challenging disease to manage, and the treatment approach involves both topical and systemic therapies, as well as phototherapy and targeted molecules. No gold standard therapy has yet been identified, and none of the treatments are curative. In patients with mild disease, control may be achieved with on-demand occlusion of topical agents. In patients with moderate-to-severe PPP, phototherapy or a classical systemic agent (acitretin being the best treatment option, especially in combination with PUVA) may be effective. Refractory patients or those with contraindications to use these therapies may be good candidates for apremilast or biologic therapy, particularly anti-IL-17A and anti-IL-23 agents. Recent PPP trials are focusing on blockage of IL-36 or IL-1 pathways, which play an important role in innate immunity. Indeed, IL-36 isoforms have been strongly implicated in the pathogenesis of psoriasis. Therefore, blockage of the IL-36 pathway has become a new treatment target in PPP, and three studies are currently evaluating the use of monoclonal antibodies that block the IL-36 receptor in PPP: ANB019 and spesolimab (BI 655130). In this review, we explore the diagnosis, screening and treatment of patients with PPP.

Palmoplantar Pustulosis: Recent Advances in Etiopathogenesis and Emerging Treatments

Palmoplantar pustulosis (PPP) is a chronic, recurrent skin disease belonging to the spectrum of psoriasis. It is characterized by an eruption of sterile pustules on the palms and soles. Recent studies in PPP have focused on genetic differences between pustular phenotypes and the role of the innate immunological system and the microbiome in the etiopathogenesis of the disease. Mutations in IL36RN (a major predisposing factor for generalized pustular psoriasis) were found in selected patients with PPP and were associated with earlier disease onset. Studies have shown that the interleukin (IL)-17 and IL-36 pathways might be involved in the pathogenesis of PPP. A microbiome has been demonstrated in the vesicopustules of PPP, and an abundance of Staphylococcus appears to be increased by smoking. Improved understanding of the underlying etiopathogenesis of PPP has led to advances in treatment options, and targeted therapies for PPP have been evaluated or are under evaluation against more than 12 molecules in ongoing clinical trials. These targets include CXCR2 (IL-8 receptor type B), granulocyte colony-stimulating factor receptor, IL-1 receptor, IL-8, IL-12, IL-23, IL-17A, IL-17 receptor, IL-36 receptor, phosphodiesterase-4, and tumor necrosis factor-α.

Interventions for chronic palmoplantar pustulosis

BACKGROUND

Palmoplantar pustulosis is a chronic inflammatory disease in which sterile, relapsing pustules appear on the palms and soles, possibly in conjunction with other symptoms. The previous Cochrane Review on this topic was published in 2006, before biological treatments were extensively used.

OBJECTIVES

To assess the effects of interventions for chronic palmoplantar pustulosis to induce and maintain complete remission.

SEARCH METHODS

We searched the following databases up to March 2019: Cochrane Skin Specialised Register, CENTRAL, MEDLINE, Embase, and LILACS. We also searched five trials registers and checked the reference lists of the included studies for further references to relevant randomised controlled trials (RCTs).

SELECTION CRITERIA

We considered RCTs including people with palmoplantar pustulosis or chronic palmoplantar pustular psoriasis assessing topical therapy, systemic therapy, combinations of topical or systemic therapies, or non-pharmacological therapies compared with placebo, no intervention, or each other.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. Our outcomes included 'Proportion of participants cleared or almost cleared', 'Proportion of participants with adverse effects serious or severe enough to cause withdrawal', 'Proportion of participants with at least 50% improvement in disease severity', and 'Proportion of participants with adverse effects'.

MAIN RESULTS

We included 37 studies (1663 participants; mean age 50 years (range 34 to 63); 24% males). These studies reported condition severity differently. Around half of the included trials stated the setting (hospitals, community clinics, or both). More than half of the studies were at high risk of bias in at least one domain. Our included studies assessed mainly systemic treatments (retinoids, ciclosporin, biologics, etretinate + PUVA (combination of psoralens and long-wave ultraviolet radiation) therapy combined, and antibiotics), but also topical treatments (dermocorticoids, vitamin D) and phototherapy (PUVA, ultraviolet A1 (UVA1)). Other interventions were assessed by single studies. The most common comparator was placebo. All results presented in this abstract were assessed in the short term (mean treatment duration was 11 weeks (range 8 to 24 weeks)) and are based on participants with chronic palmoplantar pustulosis. All outcome time point measurements were taken from baseline and assessed at the end of treatment. Short-term and long-term outcomes were defined as measurement up to 24 weeks after randomisation and between 24 and 104 weeks after randomisation, respectively. One trial (188 participants) assessed the topical vitamin D derivative maxacalcitol versus placebo and found that maxacalcitol may be more effective than placebo in achieving clearance (risk ratio (RR) 7.83, 95% confidence interval (CI) 1.85 to 33.12; low-quality evidence), and the risk of adverse effects (such as mild local irritation, pruritus, and haematological or urinary test abnormalities) is probably similar in both groups (RR 0.87, 95% CI 0.64 to 1.19; moderate-quality evidence). Severity was not reported. Two trials (49 participants) assessed PUVA therapy versus placebo or no treatment, providing very low-quality evidence. Adverse effects were reported with oral PUVA (including nausea, ankle swelling, and non-purulent conjunctivitis) and with local PUVA (including blistering, erythema, and pruritus). With regard to the systemic retinoid alitretinoin, one trial (33 participants; moderate-quality evidence) showed that alitretinoin probably makes little or no difference in reducing severity when compared to placebo (RR 0.69, 95% CI 0.36 to 1.30). A similar number of adverse events were reported in both treatment groups, including headache, cheilitis, nausea, arthralgia, and nasopharyngitis (RR 0.84, 95% CI 0.61 to 1.17). Clearance was not reported. There may be little or no difference between etanercept and placebo in achieving clearance (RR 1.64, 95% CI 0.08 to 34.28; 1 study; 15 participants; low-quality evidence); however, the 95% CI was very wide, showing there may be a difference between groups. Severity was not measured. More patients treated with placebo may achieve reduced severity than those treated with ustekinumab, but the wide 95% CI indicates there might be little or no difference between groups and there might be greater effect with ustekinumab (RR 0.48, 95% CI 0.11 to 2.13; 1 study; 33 participants; low-quality evidence). Clearance was not reported. It is uncertain whether guselkumab increases clearance when compared to placebo (2 studies; 154 participants) because the quality of evidence is very low, but guselkumab probably better reduces disease severity (RR 2.88, 95% CI 1.24 to 6.69; 1 study; 49 participants; moderate-quality evidence). Secukinumab is probably superior to placebo in reducing severity (RR 1.55, 95% CI 1.02 to 2.35; 1 study; 157 participants; moderate-quality evidence), but our clearance outcome was not reported. None of these trials reported on occurrence of adverse effects. Only two of the studies discussed above reported adverse effects serious or severe enough to cause withdrawal. Guselkumab may cause more serious adverse events when compared to placebo, but there is uncertainty due to the very wide 95% CI showing there may be little or no difference and showing more events with placebo (RR 2.88, 95% CI 0.32 to 25.80; 1 study; 49 participants; low-quality evidence). Secukinumab probably causes more serious adverse events than placebo (RR 3.29, 95% CI 1.40 to 7.75; 1 study; 157 participants; moderate-quality evidence).

AUTHORS' CONCLUSIONS

Evidence is lacking for major chronic palmoplantar pustulosis treatments such as superpotent corticosteroids, phototherapy, acitretin, methotrexate, and ciclosporin. Risk of bias and imprecision limit our confidence. Maxacalcitol may be more effective than placebo in achieving clearance in the short term (low-quality evidence), and the risk of adverse effects is probably similar (moderate-quality evidence). Oral alitretinoin is probably no more effective than placebo in reducing severity, with a similar risk of adverse effects (moderate-quality evidence). Regarding biological treatments, we are uncertain of the effect of etanercept on clearance and the effect of ustekinumab on severity (low-quality evidence). Secukinumab and guselkumab are probably superior to placebo in reducing severity (moderate-quality evidence). Adverse events not requiring withdrawal were not reported for these treatments. Reporting of serious adverse effects was incomplete: compared to placebo, secukinumab probably caused more participant withdrawals (moderate-quality evidence), but we are uncertain of the effect of guselkumab (low-quality evidence). Future trials should assess commonly used treatments using validated severity and quality of life scales.

Efficacy and Safety of Oral Alitretinoin in Hand Eczema and Palmoplantar Pustulosis in Korean Patients

Background

Previous studies have demonstrated efficacy and safety of oral alitretinoin in hand eczema (HE) whereas in palmoplantar pustulosis (PPP), which can be difficult to distinguish from HE, efficacy of alitretinoin is still controversial.

Objective

This study aimed to investigate the efficacy and safety of oral alitretinoin in HE and PPP and factors that affect the response of these disorders to alitretinoin.

Methods

We retrospectively analyzed Korean adult patients with moderate-to-severe HE and PPP treated with oral alitretinoin, 46 patients for efficacy assessment and 55 patients for safety assessment.

Results

Among 46 patients who were treated with alitretinoin for at least 1 month, 29 patients (61.1% in HE and 40.0% in PPP) showed response to alitretinoin in the median 14 weeks after treatment. Hyperkeratotic HE showed higher response rate than either vesicular HE or PPP (p=0.026 and p=0.026, respectively). However, PPP with hyperkeratotic features showed as much response as hyperkeratotic HE (p=0.554). When responders and non-responders in total patients were compared, morphology, not diagnosis or initial severity, was the only significantly different factor between the two groups. After alitretinoin discontinuation in responders, relapse rate was 63.6% (7/11) and median time to relapse was 150 days (range, 76~730 days). Adverse events occurred in 47.3% (26/55); however, there were no serious adverse events.

Conclusion

In HE or PPP, lesions with hyperkeratotic morphology can be predicted to respond well to alitretinoin regardless of diagnosis.

Palmoplantar psoriasis

Palmoplantar psoriasis refers to a localized psoriasis variant. The disease can be associated with many clinical forms, including predominantly pustular lesions to thick scaly, hyperkeratotic plaques, or an overlapping of both of them. Palmoplantar psoriasis accounts for 3-4% of all psoriasis cases in most studies. Although it is localized only on the palms and the soles, the fissures, the hardening of the tissue, and hyperkeratosis affect daily routine activities. Taking the body surface area as a measure of severity can sometimes be misleading. In clinical practice, the level of functional impairment should be taken into account rather than relying on traditional instruments to evaluate the severity. Palmoplantar psoriasis is usually managed with topical therapy as a first step. Systemic therapy is needed when the topicals fail or when the disease becomes more severe. Sometimes, biologic agents are required for adequate maintenance of clinical response.

What do we know about palmoplantar pustulosis?

Palmoplantar pustulosis is characterized by a chronic eruption of sterile pustules on palms and soles. The disease affects mainly women in the sixth and seventh decade of life. Some authors consider palmoplantar pustulosis a separate entity, whereas others consider it a condition in the spectrum of psoriasis. Aim of this study was to summarize the most recent data about PPP which aimed at establishing the nosological position of palmoplantar pustulosis. A systematic search of published literature was carried out. General characteristics of patients with PPP in different populations were present. We reviewed histological, immunological and genetic studies, as well as treatment options for PPP. PPP presents with clinical features, which are not present in psoriasis; however, the common coexistence of psoriasis vulgaris and/or positive family history for psoriasis indicates at least a close relationship between PPP and psoriasis. At present, there are not sufficient data to exclude PPP from psoriasis group.