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Urticarial vasculitis (UV) is a rare and difficult-to-treat, small-vessel leukocytoclastic vasculitis presenting with recurrent long-lasting wheals. So far, no guidelines and treatment algorithms exist that could help clinicians with the management of UV. In this review, we describe evidence on systemic treatments used for UV and propose a clinical decision-making algorithm for UV management based on the Urticarial Vasculitis Activity Score assessed for 7 days (UVAS7). Patients with occasional UV-like urticarial lesions and patients with UV with skin-limited manifestations and/or mild arthralgia/malaise (total UVAS7 ≤7 of 70) can be initially treated using the step-wise algorithm for chronic urticaria including second-generation H1-antihistamines, omalizumab, and cyclosporine A. Patients with UV with more severe symptoms (UVAS7 >7), especially those with hypocomplementemic UV, may require a multidisciplinary approach, particularly if underlying diseases, for example, systemic lupus erythematosus, cancer, or infection, are present. Immunomodulatory therapy is based on clinical signs and symptoms, and the drug availability and safety profile, and includes systemic corticosteroids, dapsone, hydroxychloroquine, anti-interleukin-1 agents, and other therapies. The level of evidence for all UV treatments is low. Prospective studies with current and novel drugs are needed and could provide further insights into UV pathogenesis and treatment., Competing Interests: Declarations. Funding: Open Access funding enabled and organized by Projekt DEAL. Conflicts of Interest/Competing Interests: Nikolai Dario Rothermel, Carolina Vera Ayala, Leonie Shirin Herzog, Polina Pyatilova, and Sophia Neisinger have no conflicts of interest that are directly relevant to the content of this article. Emek Kocatürk was a speaker/consultant and/or advisor for and/or has received research funding from Novartis, Menarini, LaRoche Posey, Sanofi, Bayer, Abdi İbrahim, and Pfizer outside of the submitted work. Indrashis Podder has no conflicts of interest to declare in relation to the current work. Outside of it, he is or recently was a speaker and/or advisor for Menarini, Sun Pharmaceuticals, Glenmark, Cipla, and Alkem Laboratories. Jie Shen Fok has previously received speaker honorarium or/and travel sponsorship from CSL Behring, Menarini, Viatris, Takeda, and Novartis outside of submitted work. Manuel P. Pereira has received research funding from Almirall and Pfizer; is an investigator for Allakos, Celldex Therapeutics, Incyte, Sanofi, and Trevi Therapeutics; and has received consulting fees, speaker honoraria and/or travel fees from AbbVie, Beiersdorf, Celltrion, Doctorflix, Eli Lilly, GA2LEN, Galderma, Menlo Therapeutics, Novartis, P.G. Unna Academy, Sanofi, Streamed UP, and Trevi Therapeutics. Margarida Gonçalo is or has been advisor and/or received fees for lectures from AbbVie, Astra-Zeneca, Leo Pharma, Lilly, Novartis, Pfizer, Sanofi, and Takeda outside of the submitted work. Melba Munoz is or recently was, outside of the submitted work, a speaker and/or advisor for and/or has received research funding from Jasper Therapeutics, Celldex Therapeutics, Takeda, GA2LEN, UNEV, Astra Zeneca, and Roche. Karoline Krause has no conflict of interest related to this work. Outside of it, she received research funding and or honoraria from Bayer, Beiersdorf, Berlin Chemie, CSL Behring, Moxie, Novartis, Roche/CHUGAI, Sobi, and Takeda. Marcus Maurer is or recently was, outside of the submitted work, a speaker and/or advisor for and/or has received research funding from Allakos, Alexion, Alvotech, Almirall, Amgen, Aquestive, argenX, AstraZeneca, Celldex, Celltrion, Clinuvel, Escient, Evommune, Excellergy, GSK, Incyte, Jasper, Kashiv, Kyowa Kirin, Leo Pharma, Lilly, Menarini, Mitsubishi Tanabe Pharma, Moxie, Noucor, Novartis, Orion Biotechnology, Resoncance Medicine, Sanofi/Regeneron, Santa Ana Bio, Septerna, Servier, Third HarmonicBio, ValenzaBio, Vitalli Bio, Yuhan Corporation, and Zurabio. Hanna Bonnekoh was a speaker/consultant and/or advisor for and/or has received research funding AbbVie, Novartis, Sanofi Aventis, and ValenzaBio outside of the submitted work. Pavel Kolkhir was a speaker/consultant and/or advisor for and/or has received research funding from Novartis, ValenzaBio, and Roche outside of the submitted work. Ethics Approval: Not applicable. Consent to Participate: Not applicable. Consent for Publication: Not applicable. Availability of Data and Material: This is a review article and does not involve human subjects, therefore no primary data were used. Data from studies presented in this article are summarized in the tables and supplementary tables. Code Availability: Not applicable. Authors’ Contributions: NR, HB, and PK contributed to the conceptualization, methodology, data curation, and writing (original draft). AR, CVA, EK, IP, JF, LH, MP, MG, MMu, PP, and SN contributed to the methodology, data curation, and writing (original draft). MM and KK contributed to data curation and writing (review and editing). All authors contributed to the consensus process that led to this article, reviewed the literature, critically reviewed and revised the article, and proofread and approved the final version., (© 2024. The Author(s).)

The occurrence of pruritus in psoriasis was previously underestimated but is a significant burden. Secukinumab (SEC), a monoclonal anti-interleukin-17A antibody, efficiently controls signs of psoriasis, but the effect on pruritus and cutaneous neuroanatomy remained unknown. The primary objective of this study (NCT02362789) was to evaluate the superiority of SEC treatment vs placebo on pruritus intensity (visual analogue scale; VAS). Furthermore, the treatment-dependent course of pruritus in association with absolute Psoriasis Area Severity Index (PASI) score, as well as cutaneous histopathology and neuroanatomy, was assessed. Open-label SEC 300 mg s.c. was administered regularly until week 16. Patients who reached a ≥ 98% PASI reduction (PASI ≥ 98) were randomized to receive either placebo or SEC up to week 32. Punch biopsies were collected from lesional psoriatic (baseline, weeks 16 and 32) and non-lesional (baseline) skin for histopathological and neuroanatomical analyses. VAS scores improved significantly after open-label SEC treatment but relapsed upon placebo (29.92 ± 33.8) compared with SEC (12.30 ± 22.6; p = 0.036). After SEC-dependent improvement in PASI, histopathology, marker expression and neuroanatomy, relapse was observed with treatment discontinuation in all parameters except neuroanatomy. SEC was superior to placebo by efficiently controlling reduced pruritus intensity, clinically normalizing skin lesions, and reversing histopathological abnormalities. The neuroanatomy recovered upon SEC and remained stable even after withdrawal.

Chronic spontaneous urticaria (CSU) is a debilitating, inflammatory skin condition characterized by infiltrating immune cells. Available treatments are limited to improving the signs and symptoms. There is an unmet need to develop therapies that target disease-driving pathways upstream of mast cell activation to inhibit or delay the progression of CSU and associated comorbidities. Here, we aim to define disease modification due to a treatment intervention and criteria that disease-modifying treatments (DMTs) must meet in CSU. We have defined disease modification in CSU as a favorable treatment-induced change in the underlying pathophysiology and, therefore, the disease course, which is clinically beneficial and enduring. A DMT must fulfil the following criteria: (1) prevents or delays the progression of CSU, (2) induces long-term, therapy-free clinical remission, which is the sustained absence of CSU signs and symptoms without the need for treatment, and (3) affects the underlying mechanism of CSU, as demonstrated by an effect on disease-driving signals and/or a biomarker. DMTs in CSU should slow disease progression, achieve long-lasting disease remission, target disease-driving mechanisms, reduce mast cell-activating IgE autoantibodies, target cytokine profile polarization, and normalize the gut microbiome and barrier. Treating CSU at the immune system level could provide valuable alternatives to pharmacotherapy in CSU management. Specific DMTs in CSU are yet to be developed, but some show potential benefits, such as inhibitors of Bruton's Tyrosine Kinase, IL-4 and IL-13. Future therapies could prevent CSU signs and symptoms, achieve long-term clinical benefits after discontinuing treatment, and prevent associated concomitant disorders., (© 2024 The Author(s). Allergy published by European Academy of Allergy and Clinical Immunology and John Wiley & Sons Ltd.)

The term "urticaria" was first introduced by William Cullen in the eighteenth century. Urticaria is a common mast cell-mediated cutaneous disease presenting with pruritic wheals, angioedema, or both. It is classified as acute (≤6 weeks) or chronic (>6 weeks) and as spontaneous (no definite triggers) or inducible (definite and subtype-specific triggers). The international urticaria guideline on the definition, classification, diagnosis, and management of urticaria is revised every 4 years. The global network of Urticaria Centers of Reference and Excellence, the biggest and most active consortium of urticaria specialists, offers physicians and patients several research, educational, and digital care initiatives., Competing Interests: Disclosure M. Maurer is or recently was a speaker and/or advisor for and/or has received research funding from Allakos, Almirall, Spaim, Alvotech, Amgen, United States, Aquestive, Aralez, AstraZeneca, United Kingdom, Bayer, Germany, Celldex, United States, Celltrion, South Korea, Evommune, GSK, Ipsen, France, Janssen, United States, Kyowa Kirin, LEO Pharma, Denmark, Lilly, Menarini, Mitsubishi Tanabe Pharma, Japan, Moxie, Noucor, Novartis, Switzerland, Orion, Pfizer, United States, Resoncance Medicine, Sanofi/Regeneron, Septerna, Third Harmonic Bio, ValenzaBio, Yuhan Corporation, South Korea, and Zurabio. M.P. Pereira is an investigator for Allakos, Celldex Therapeutics, Incyte, Sanofi and Trevi Therapeutics and is/was an advisor and/or speaker and/or has received research funding from AbbVie, United States, Almirall, Beiersdorf, Germany, Eli Lilly, GA(2)LEN, Galderma, Switzerland, Menlo Therapeutics, Novartis, P.G. Unna Academy, Sanofi, United States and Trevi Therapeutics. P. Kolkhir is or recently was a speaker and/or advisor for and/or has received research funding from Novartis, Roche, Switzerland, and ValenzaBio outside of submitted work., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Purpose of Review: Chronic inducible urticaria (CIndU) is a group of long-persisting and challenging to manage diseases, characterized by recurrent wheals and angioedema induced by definite triggers. In this review, we address recent findings on CIndU pathogenesis, diagnosis as well as its treatment, and we discuss novel potential targets that may lead to the development of more effective therapies for CIndU patients., Recent Advances: Meaningful advances in the understanding of its pathogenesis have been reported in the last decades. Novel CIndU-specific patient-reported outcome measures enable a closer and better evaluation of patients. CIndU is a hard-to-treat disease that highly impairs quality of life (QoL) of affected patients. Provocation tests allow to diagnose CIndU subtypes. The only licensed and recommended treatment for CIndU are second generation non-sedating H1-antihistamines, which lack efficacy in many cases. Omalizumab off-label use has been assessed in all types of CIndU with overall good outcomes. Promising emerging therapies currently assessed in chronic spontaneous urticaria are paving the path for novel treatments for CIndU., (© 2024. The Author(s).)

Chronic itch is a frequent and debilitating condition that greatly affects the quality of life of those affected. In a subset of patients, damage to the peripheral or central nervous system constitutes the cause of the itch. Small-fiber neuropathy, nerve compression syndromes, post-herpetic neuralgia, scars and burns are possible conditions affecting the peripheral nervous system potentially causing itch, whereas space-occupying lesions affecting the spinal cord and stroke are examples of conditions that may induce central itch. Neuropathic itch starts on normal appearing skin, is often accompanied by pain sensations and other dysesthesias, and usually relieved by local cold application. Its distribution depends on the affected site of the somatosensory system. A comprehensive medical history is paramount to reach the diagnosis, while complementary diagnostics with skin biopsies for the investigation of cutaneous neuromorphological alterations or medical imaging to rule out nerve impingement may be advised in selected cases. Topical agents such as capsaicin or local anesthetics as well as systemic drugs such as gabapentinoids, antidepressants and opioid receptor modulators are used in the treatment of neuropathic itch. This review article provides an overview of the clinical features, underlying causes, diagnostic workup and therapeutic approach in neuropathic itch., (© 2024. The Author(s), under exclusive licence to Springer Medizin Verlag GmbH, ein Teil von Springer Nature.)

Chronic prurigo is a very debilitating skin condition characterized by the development of multiple pruriginous nodules, papules or plaques due to a prolonged scratching behavior as a result of chronic itch. Patients often experience anxiety, depression or sleep impairment leading to a substantial decrease in quality of life. Due to the complex pathophysiology and diversity in clinical presentation, managing chronic prurigo remains a challenge. Disease-specific guidelines provide appropriate diagnostic measures and recommend a step-wise therapeutic approach. With the increase of pharmaceutical interest in chronic prurigo, several innovative therapies including monoclonal antibodies and small molecules are currently being investigated for chronic prurigo. This continuing medical education (CME) article provides an overview on various aspects of chronic prurigo, especially on epidemiology, pathophysiology, clinical presentation, diagnostic and therapeutic approach, and innovate therapeutic options., (© 2023. The Author(s), under exclusive licence to Springer Medizin Verlag GmbH, ein Teil von Springer Nature.)

Background: Chronic scratching imposes a major stress on the skin and can lead to itch intensity worsening, and consequently, patients may enter an itch-scratch cycle. This repetitive mechanical stress can result in lichenification, worsening of epidermal barrier function, and enhanced cutaneous inflammation. Furthermore, a reduction of intraepidermal nerve fibers was previously described in lichenification., Aim: The aim of this study was to investigate the influence of chronic scratching on the epidermal neuroanatomy and on sensory changes, in particular the prevalence of hyperknesis and alloknesis in patients after mechanical, chemical, and electrical stimuli., Methods: Analyses were performed on pruritic lichenified (chronically scratched), pruritic non-lichenified (not chronically scratched), and non-pruritic non-lesional (unaffected) skin areas of patients with inflammatory pruritus, i.e., atopic dermatitis ( n = 35), and neuropathic pruritus, i.e., brachioradial pruritus ( n = 34) vs. healthy matched controls ( n = 64). Our fine-grained spatial skin characterization enabled specifically studying the differential effects of chronic scratching in inflammatory and neuropathic itch., Results: Analysis of intraepidermal nerve fiber density showed rarefaction of fibers in all three skin areas of patients compared with healthy controls in both diagnoses. Even more, the two pruritic areas had significantly less nerve fibers than the unaffected skin, whereas electrically induced itch was massively increased. Epidermal branching of the remaining nerve fibers in lichenified/chronically scratched skin was increased, particularly in patients with brachioradial pruritus, which may contribute to the pronounced local neuronal sensitivity. Hyperknesis and alloknesis were found to increase independently of lichenification., Conclusion: Our results indicate that chronic scratching may not affect intraepidermal nerve fiber density but leads to a stronger branching pattern of intraepidermal nerve fibers, which may contribute to local hypersensitivity. The increased sensitivity in the pruritic areas suggests mechanisms of peripheral sensitization, whereas the increased sensation of electrically and chemically induced itch in unaffected skin indicates central sensitization for itch., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision., (Copyright © 2023 Renkhold, Wiegmann, Pfleiderer, Süer, Zeidler, Pereira, Schmelz, Ständer and Agelopoulos.)

This article presents the case of a patient with massive pruritus sine materia. Naloxone was proven as quick and effective therapy which led to a complete reduction of itching., (© 2022. The Author(s), under exclusive licence to Springer Medizin Verlag GmbH, ein Teil von Springer Nature.)

Scratching and scratch-induced injuries, including neuroanatomical alterations, are key characteristics of chronic pruritus entities of different origins. The aim of this study was to link gene expression (array hybridization, qPCR) with DNA methylation (array hybridization) and neuroanatomy (PGP9.5 staining) in chronic nodular prurigo (CNPG), atopic dermatitis (AD), brachioradial pruritus (BRP), and matched healthy controls. Specific signatures of gene expression and DNA methylation clearly discriminated pruritic lesional skin from nonpruritic skin in CNPG and from healthy skin of volunteers, respectively. Although intraepidermal nerve fiber density was indiscriminately reduced, the level of epidermal branching, assessed by a semiquantitative pattern analysis, differentiated the entities (CNPG > BRP > AD). Correspondingly, repellent SEMA3A showed the highest expression in AD, whereas axonal growth-promoting nerve GF was most prominent in CNPG and BRP. Overexpression of genes for nerve fiber regeneration (NELL2/NFKB/ARTN) was found in AD and CNPG but not in BRP. Our findings suggest that differential branching patterns rather than mere innervation density separate chronic itch conditions and reflect disease-specific local expression profiles. In pruritic dermatoses (AD and CNPG), nerve injury and subsequent sprouting may primarily result from chronic scratching, whereas genuine neuropathy is expected to underlie BRP., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

We report a case of a 57-year-old slightly obese woman with localized itch on the arms accompanied by stinging and burning sensations. A few excoriations were observed upon clinical examination. The MRI examination of the cervical spine revealed a meningioma at C5/C6 level. The diagnosis of brachioradial pruritus due to compression of the cervical myelon was further supported by a positive ice-pack sign. Disc herniation or prolapse, foraminal stenosis and degenerative alterations constitute other possible causes of brachioradial pruritus., (© 2021. Springer Medizin Verlag GmbH, ein Teil von Springer Nature.)

Pruritus in pregnancy is a common and burdensome symptom that may be a first sign of a pregnancy-specific pruritic disease (atopic eruption of pregnancy, polymorphic eruption of pregnancy, pemphigoid gestationis, and intrahepatic cholestasis in pregnancy) or a dermatosis coinciding with pregnancy by chance. Despite its high prevalence, pruritus is often underrated by physicians, and data regarding the safety profiles of drugs for pruritus are very limited. In this review, we illustrate the epidemiology, possible pathophysiology, clinical characteristics, and diagnostic workup of various pregnancy-related diseases and discuss antipruritic treatments. The prevalence of pruritus in pregnancy demonstrates the importance of symptom recognition and the need for an holistic approach, taking into account both the potential benefits for the patient and the potential risks to the fetus., (© 2022. The Author(s).)

Human hands are complex structures essential for a variety of functions in everyday life. This study prospectively investigated the clinical features of hand pruritus and the resulting functional impairment and disease-related burden in 395 patients with chronic pruritus (210 females, median age 59 years). Moderate to very severe hand pruritus was reported by 91.2% of patients, while 79% perceived additional sensory symptoms, such as burning, pain or tingling. A long duration of pruritus occurred in most cases (>6 months: 71.4%). A considerable proportion of patients showed moderate to severe impairment in the use of their hands (40.2%), performance of daily activities (65.0%) and quality of life (45.2%). Disease severity and burden is particularly high when both the palms and the backs of the hands are affected, and when pain is present simultaneously. Pruritus located on the hands is impairing and burdensome due to the functional relevance of the hands in everyday life.

Chronic pruritus of unknown origin is established when no underlying origin for pruritus can be determined. This retrospective cohort study aimed to determine the clinical profile and disease-related burden of chronic pruritus of unknown origin. A total of 263 patients (female/male: 154/109, median age 55 years) were included. Moderate to severe itch intensities were recorded (median average itch: 5.5/10, n = 200; median worst itch: 7.5/10, n = 199). In most cases pruritus lasted longer than 1 year (77.6%), occurred daily (68.2%), occurred in attacks (72.8%), and was often accompanied by dysaesthesias, such as burning, tingling and stinging. Quality of life was moderately impaired, while 22.2% and 12.4% of patients showed pathological anxiety and depression scores. Scratch lesions were associated with higher intensities of itch and greater impairment of quality of life, while women were more burdened by the disease than men. Chronic pruritus of unknown origin may occur at any age and the majority of patients endure severe itch with substantial disease-related burden.

Chronic prurigo is a pruritic disease characterized by the development of pruriginous lesions due to scratching. The number of lesions is representative of the stage of the disease, while the presence of excoriations reflects the scratching activity. Aim of this study was to validate a new developed tool for the objective assessment of chronic prurigo. Investigator's Global Assessment scales for stage and activity were completed for 187 patients with chronic prurigo, who also reported patient-reported outcomes for itch intensity and quality of life. To assess the reliability and objectivity of the Investigator's Global Assessment, 5 independent raters completed the Investigator's Global Assessment scales for 8 patients twice. The scores increased with increased intensity of pruritus. The Investigator's Global Assessment stage scales correlated strongly with each other (Kendall's-tau-b 0.62) and moderately with the Investigator's Global Assessment activity scale (Kendall's-tau-b 0.47). Intra-rater test-retest reliability was excellent for all items, while the congruence among raters was very good for Investigator's Global Assessment - chronic prurigo activity (Kendall's W 0.84) and good for Investigator's Global Assessment stage scales (Kendall's W 0.747). Investigator's Global Assessment - chronic prurigo stage and activity are thus the best Investigator's Global Assessment instruments for use in assessing chronic prurigo.

Chronic nodular prurigo is characterized by recalcitrant itch. Patient perspectives on therapeutic goals, satisfaction with therapy and efficacy of therapeutic regimens for this condition are unknown. This questionnaire study examined these issues in 406 patients with chronic nodular prurigo from 15 European dermatological centres. Improvements in itch, skin lesions and sleep were the most important goals. Emollients, topical corticosteroids and antihistamines were the most frequently used treatments, while a minority of patients were prescribed potent medications, such as systemic immunosuppressants and gabapentinoids. Most patients were not satisfied with their previous therapy (56.8%), while 9.8% did not receive any therapy despite having active disease. A substantial number of respondents (28.7%) considered none of the therapeutic options effective. Although chronic nodular prurigo is a severe disease, most patients were not treated with potent systemic drugs, which may contribute to the high levels of dissatisfaction and disbelief in available therapies. Specific guidelines for chronic nodular prurigo and the development of novel therapies are necessary to improve care.

Chronic pruritus (CP) is a highly prevalent, difficult-to-treat, and burdensome condition. Today, multiple topical and systemic therapy concepts are available for the treatment of CP. Current guidelines recommend, besides topical treatments, the use of a vast array of mostly off-label systemic drugs with different mechanisms, including antihistamines, gabapentinoids, antidepressants, immunosuppressive drugs, and μ‑opioid receptor antagonists. The choice of the right agent depends on the indication, the safety profile of the drug, and patient-specific features, such as comorbidities and comedication. Thanks to a deeper understanding of the pathophysiology of CP, novel drugs have been developed and have already shown antipruritic efficacy in clinical studies and case reports. Of note, phosphodiesterase‑4 inhibitors as topical agents and monoclonal antibodies, neurokinin‑1 receptor antagonists, Janus kinase inhibitors, and opioid receptor modulators as systemic agents are in the frontline of innovative CP treatment. Other promising targets include structures of the peripheral and central nervous system which are involved in itch signaling. This article provides an overview of currently available topical and systemic therapies for CP and their indications and discusses novel innovative agents and promising new targets in CP.

Chronic nodular prurigo presents with multiple pruriginous nodules and severe pruritus. This study aims to explore the treatment course and regimens in patients with chronic nodular prurigo and to analyse predictive factors contributing to therapeutic success. A total of 325 patients with chronic nodular prurigo (male 37.5%) were analysed concerning demographic data, pruritus intensity, medical history, psychological impairment, quality of life, treatment duration, regimens and outcome. These parameters were compared with 325 sex- and age-matched patients with chronic pruritus on non-lesional skin. Treatment success was dependent on duration and regime of treatment and independent of age, sex and initial itch intensity. Non-responders displayed a higher percentage of inflamed nodules, a higher portion of excoriated nodules and a higher impairment of quality of life and mood factors before initiation of treatment. Gabapentinoids and immunosuppressants proved to be the most successful therapeutic agents. Compared with patients with chronic pruritus, those with chronic nodular prurigo needed longer duration of therapy.

Chronic pruritus is a frequent global condition. The pathophysiology, underlying aetiology, clinical manifestation, associated burden and response to therapy of chronic pruritus varies from patient to patient, making clinical research and management of this condition challenging. There are still several unmet needs, such as the need to standardize translational research protocols, diagnostic and therapeutic procedures and to enhance the knowledge of the humanistic and economic burden associated with chronic pruritus. Basic and clinical research is of the utmost importance to target these matters. Clinical research has the potential to identify new relevant mechanisms in affected patients, which may lead to identification of novel therapy targets. This article discusses in depth current shortcomings in the daily care of patients with chronic pruritus and the challenges clinical researchers and physicians treating chronic pruritus face in addressing these matters.

Neurophysiological mechanisms leading to chronicity of pruritus are not yet fully understood and it is not known whether these mechanisms diverge between different underlying diseases of chronic pruritus (CP). This study aimed to detect such mechanisms in CP of various origins. A total of 120 patients with CP of inflammatory origin (atopic dermatitis), neuropathic origin (brachioradial pruritus), and chronic prurigo of nodular type, the latter as a model for chronic scratching, as well as 40 matched healthy controls participated in this study. Stimulation with cowhage induced a more intensive itch sensation compared with stimulation with other substances in all patient groups but not in healthy controls, arguing for sensitization of cutaneous mechano- and heat-sensitive C-fibers in CP. All patient groups showed a decreased intraepidermal nerve fiber density compared with controls. A decreased condition pain modulation effect was observed in all patient groups compared with controls, suggesting a reduced descending inhibitory system in CP. In sum, CP of different etiologies showed a mixed peripheral and central pattern of neuronal alterations, which might contribute to the chronicity of pruritus with no differences between pruritus entities. Our findings may contribute to the development of future treatment strategies targeting these pathomechanisms., (Copyright © 2019 The Authors. Published by Elsevier Inc. All rights reserved.)

Chronic prurigo impairs quality of life and is immensely challenging to treat. Until recently, no clear definition or classification system was available for this disease. A European task force specialized in pruritus defined chronic prurigo as a distinct disease characterized by chronic pruritus, a lengthy scratching behaviour and the presence of pruriginous lesions. Papular, nodular, plaque, umbilicated and linear prurigo were identified as clinical subtypes according to the most prominent lesion type observed in the physical examination. Various clinical and pathophysiological aspects, which are common across the range of clinical manifestations of chronic prurigo, argue for chronic prurigo as a disease in its own right. Chronic prurigo should be clearly demarcated from other conditions such as so-called acute or subacute prurigo forms as well as from psychogenic self-inflicted skin lesions, since different diagnostic criteria apply for these diseases. This viewpoint essay provides a detailed definition and classification of chronic prurigo including its obligatory and associated diagnostic criteria and discusses chronic prurigo as a distinct disease as well as the demarcation to other relevant conditions., (© 2019 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Central sensitization induces pain augmentation in chronic pain states. An analogous mechanism is speculated for chronic pruritus. This study compared patients with chronic pruritus (n = 79) of different origins (atopic dermatitis, chronic pruritus on non-lesional skin, chronic prurigo) and healthy controls (HC, n = 54) with regard to itch intensity and qualities of sensory symptoms after selective peripheral nerve fibre activation by electrical stimulation at 5 Hz (surrogate for C-fibre function) and 2,000 Hz (surrogate for Aβ-fibre function) using a Neurometer®. Electrically-induced itch was more intense in patients with chronic pruritus than in HC, but patients with chronic pruritus did not report "itch" more often than HC at 5 Hz. Stimulation at 2,000 Hz induced more pricking and tingling, but less throbbing in patients with chronic pruritus compared with HC. Treatment with cooling compound reduced clinical and experimental itch, but did not alter the distribution of sensory symptoms. These data show hyperknesis in chronic pruritus of various origins, arguing for common central sensitization mechanisms.

Chronic pruritus (CP) is often accompanied by paresthetic sensations like warmth, burning and stinging. The aim of this study was to analyze, whether divergent sensations are linked to structural and functional skin alterations in clinically diagnosed CP patients. Clinical responses to capsaicin, histamine, and to thermal and mechanical stimulation, intraepidermal nerve fiber density, and epidermal expression of transient receptor potential (TRP)-channels were investigated in healthy controls, and in CP patients, reporting either warmth (CP-W) or neuropathic sensations (CP-N). In CP-W, pinprick hyperalgesia and increased sensitivity to capsaicin were aligned with increased epidermal TRPV1 expression, while smaller histamine axon reflex erythema matched with significantly reduced intraepidermal nerve fiber density. CP-N showed earlier onset of sensations after capsaicin stimulation, significantly increased warmth detection threshold, and higher epidermal expression of TRPV4 compared to healthy controls. The present study contributes to the neurobiological understanding of the divergence of sensory sensations in CP, indicating new treatment targets.

Introduction: Chronic pruritus (CP) is a multidimensional condition severely affecting the quality of life of those affected. Although a multitude of topical and systemic agents are recommended for CP of different origins, the condition often remains refractory to treatment. However, a deeper understanding of the pathophysiology of CP is leading to the development of novel antipruritic drugs., Areas Covered: This paper reviews antipruritic therapies in development by gathering data from recently published articles and clinical trials databases. Interleukin-31 antibodies and other biologics, neurokinin-1 receptor antagonists, opioid-receptor agonists/antagonists, TrkA-antagonists, and ileal bile acid transporter inhibitors are discussed., Expert Opinion: Clinical trials have rendered promising data on the antipruritic efficacy and safety of novel drugs, but further studies are necessary to enhance our understanding of the different conditions associated with CP. High-quality clinical trial data is necessary for these agents to be approved for the treatment. Basic research should be intensified to identify pathways relevant for CP and to further the development of new specific antipruritic drugs.

Background: Prurigo nodularis (PN) is a poorly understood, understudied pruritic dermatosis that reduces quality of life., Objective: To characterize the demographics and comorbidities associated with PN., Methods: Cross-sectional study of patients 18 years and older who were seen at the Johns Hopkins Health System between December 6, 2012, and December 6, 2017., Results: Over the past 5 years, 909 patients with PN were seen at Johns Hopkins Health System. African American patients were 3.4 times more likely to have PN than white patients were (odds ratio [OR], 3.4; 95% confidence interval [CI], 2.9-3.9; P < .001). A comparison of the study patients and race-matched controls revealed that PN was significantly associated with a variety of systemic, cardiovascular, and psychiatric comorbidities, including chronic kidney disease, chronic hepatitis C, chronic obstructive pulmonary disease, congestive heart failure, depression, and atopic dermatitis. Black patients with PN were 10.5 times more likely (OR, 10.5; 95% CI, 7.9-13.9; P < .001) to have HIV than were race-matched controls with atopic dermatitis, and 8 times more likely (OR, 8.0; 95% CI, 5.7-11.1; P < .001) to have HIV than were African American patients with psoriasis., Limitations: Our data describe patients seen by 1 hospital system. Our data identify associated conditions and comorbidities but are unable to support a causal relationship., Conclusion: PN disproportionately affects African Americans and is associated with several systemic conditions, including HIV, chronic kidney disease, and diabetes., (Copyright © 2018 American Academy of Dermatology, Inc. Published by Elsevier Inc. All rights reserved.)

Introduction: The prevalence of chronic pruritus (CP) in the general population is high and increases with age. Owing to high rates of comorbidities and polypharmacy in patients aged 65 or older, the clinical management of these patients is challenging., Areas Covered: In this review, the authors discuss the available therapy options for patients aged ≥ 65 with CP, including emollients for dry skin, topical therapies, phototherapy and systemic agents for CP of various origins., Expert Opinion: For multimorbid patients, topical substances and phototherapy constitute the best initial options. If systemic drugs are needed, the potential side-effects need to be closely monitored. In elderly patients, multiple possible factors for CP, including dermatological and systemic diseases, may be found, complicating the treatment of the underlying cause. In these cases, or when the origin remains unknown, a step-wise symptomatic therapy is recommended. The therapeutic choices should be made on an individual basis after carefully outweighing possible risks and benefits. Novel agents such as neurokinin-1 receptor antagonists and opioid-targeting drugs show promising antipruritic effects on refractory CP and seem to be well tolerated. They may be useful for elderly patients, who cannot tolerate conventional systemic agents.

Brachioradial pruritus (BRP) and notalgia paraesthetica (NP) represent 2 of the most common neuropathic itch syndromes. A total of 58 consecutive patients presenting at the Center for Chronic Pruritus, University Hospital Münster, were analysed with regard to clinical presentation, anatomical and morphological pathologies, impairment in quality of life, and response to treatment with topical capsaicin. Patients with BRP reported stinging and burning more often than those with NP. In the BRP group structural magnetic resonance imaging abnormalities more frequently correlated with localization of the symptoms compared with in patients with NP. In addition, intraepidermal nerve fibre density was decreased in lesional skin in patients with BRP, but not in those with NP, confirming the neuropathic origin in BRP. Topical capsaicin resulted in a significantly higher alleviation of itch and pain intensity and improvement in quality of life in patients with BRP compared with those with NP, which may reflect clinical and aetiological differences between the conditions.

Patient care for those affected by chronic pruritus is remarkably complex due to its high prevalence and multifactorial nature. It requires a comprehensive assessment of the patient's medical history, extensive diagnostic procedures, and long treatment duration, including management of possible accompanying disorders such as sleep disturbances and mental distress. It is important to prioritize patient's needs when developing a therapeutic treatment plan. Standardized questionnaires and scales should be used to better analyze the patient history, quality of life, symptom intensity, and course of treatment. These can be distributed via digital platforms, allowing for more effective communication between the treating agents and gathering of large volumes of data in central databases. In today's health care system, it is essential for physicians with itch-related specializations and specialized itch centers to cooperate. It is thus crucial to focus efforts on the further development of specialized treatment centers and training courses for medical practitioners. There are, however, various regulatory and economic barriers to overcome in the modern health care system before patients with chronic pruritus can be offered the best possible care. Accordingly, health care authorities should be made aware of the difficulties associated with the management of chronic pruritus and of the high individual and societal burden it represents., Competing Interests: Sponsorships or competing interests that may be relevant to content are disclosed at the end of this article.

Chronic pruritus remains a central societal issue because of its high occurrence and the substantial decrease in quality of life it may cause to affected individuals. Not only dermatological conditions, but also systemic, neurological, or psychiatric diseases may lead to chronic pruritus. Additionally, various underlying conditions may coexist or the cause may be unknown. Due to its heterogeneity, the therapeutic approach is complex and remains a challenge for the clinician. Basic measures such as emollients to avoid xerosis and treatment of the underlying disease should be initiated regardless of the duration of the symptom. Depending on the indication, other topical (e.g., calcineurin inhibitors, topical corticosteroids, capsaicin) and systemic agents (immunosuppressive drugs, gabapentinoids, antidepressants, mu-opioid receptor antagonists) may provide further relief. Additionally, accompanying disorders such as sleep impairment, depression, or anxiety should also be treated. New insights into pathways involved in the development and maintenance of chronic pruritus have led in the past years to the development of a considerable number of novel antipruritic drugs. Several randomized controlled trials have been recently completed or are currently underway testing biological compounds with promising approaches. These include antagonists for nerve growth factor, neuropeptides, histamine 4 receptors, certain interleukin receptors, and opioid receptors.

In recent years, measurement of the intraepidermal nerve fiber (IENF) density has gained relevance in the diagnostics of chronic pruritus. This method allows the objectification and quantification of a small-fiber neuropathy, which may manifest clinically with pruritus, pain or dysesthetic sensory symptoms, such as burning, stinging and tingling sensations or numbness. Upon suspicion of a small-fiber neuropathy as a cause for chronic pruritus, targeted diagnostic procedures are essential for the early detection of the neuroanatomical changes. After a punch biopsy of the lower leg, the obtained tissue undergoes an immunofluorescence staining process with a primary antibody against the protein gene product 9.5. The IENFs can thus be detected and are quantified according to pre-determined guidelines based on an international consensus. In addition to morphological changes, functional impairment of small-fibers can be assessed using quantitative sensory testing by assessing detection and pain thresholds of various thermal and mechanic modalities. This method, however, is time-consuming and requires a specialized investigator, and thus it is not routinely used in the diagnostic investigation of chronic pruritus. Diagnosing a small-fiber neuropathy underlying chronic pruritus has therapeutic relevance. If possible, the underlying cause of the neuropathy should be treated. Alternatively, symptomatic therapy options include topical (capsaicin) and systemic (anticonvulsants and/or antidepressants) agents. Chronification processes may lead to refractory pruritus, and thus treatment should be initiated as soon as possible. The aim of this review is to present and discuss the measurement of the IENF density as a diagnostic tool and its role in the management of patients with chronic pruritus. A brief case report is presented to better illustrate the role of this diagnostic method in the clinical setting.

Chronic pruritus arises not only from dermatoses, but also, in up to half of cases, from extracutaneous origins. A multitude of systemic, neurological, psychiatric, and somatoform conditions are associated with pruritus in the absence of skin disease. Moreover, pruritus is a frequently observed side effect of many drugs. It is therefore difficult for physicians to make a correct diagnosis. Chronic pruritus patients frequently present to the dermatologist with skin lesions secondary to a long-lasting scratching behavior, such as lichenification and prurigo nodularis. A structured clinical history and physical examination are essential in order to evaluate the pruritus, along with systematic, medical history-adapted laboratory and radiological tests carried out according to the differential diagnosis. For therapeutic reasons, a symptomatic therapy should be promptly initiated parallel to the diagnostic procedures. Once the underlying factor(s) leading to the pruritus are identified, a targeted therapy should be implemented. Importantly, the treatment of accompanying disorders such as sleep disturbances or mental symptoms should be taken into consideration. Even after successful treatment of the underlying cause, pruritus may persist, likely due to chronicity processes including peripheral and central sensitization or impaired inhibition at spinal level. A vast arsenal of topical and systemic agents targeting these pathophysiological mechanisms has been used to deter further chronicity. The therapeutic options currently available are, however, still insufficient for many patients. Thus, future studies aiming to unveil the complex mechanisms underlying chronic pruritus and develop new therapeutic agents are urgently needed.

Purpose of Review: Gender differences are well known in clinical pain and pain-related diseases. However, studies analyzing gender differences in postoperative pain yielded inconsistent finding. The aim of this review was to summarize recent findings on this matter., Recent Findings: We found 58 recently published studies (September 2013-March 2015) assessing gender differences on patients undergoing various surgical procedures. Studies focusing on one type or one category of surgical procedures suggest that women report higher postoperative pain scores after thoracic, cardiac and neurosurgical procedures. However, gender differences after abdominal and orthopedic surgeries were inconsistent and after oral surgery inexistent. Studies including various surgical procedures indicate a more consistent gender difference, presumably because of the greater number of patients included. However, the net difference in almost every study was small., Summary: Women seem to be at higher risk to develop severe postoperative pain but gender differences seem to be small and of low clinical relevance. We argue that major confounders may explain discrepancies between studies. Large prospective studies and registry data assessing gender aspects including confounders need to be done in the future.

Unlabelled: Following the resolution of a severe inflammatory injury in rodents, administration of mu-opioid receptor inverse agonists leads to reinstatement of pain hypersensitivity. The mechanisms underlying this form of latent pain sensitization (LS) likely contribute to the development of chronic pain, but LS has not yet been demonstrated in humans. Using a C57BL/6 mouse model of cutaneous mild heat injury (MHI) we demonstrated a dose-dependent reinstatement of pain sensitization, assessed as primary (P < 0.001) and secondary hyperalgesia (P < 0.001) by naloxone (0.3–10 mg/kg), 168 hrs after the induction of MHI. Forward-translating the dose data to a human MHI model (n = 12) we could show that LS does indeed occur after naloxone 2 mg/kg, 168 hrs after a MHI. Our previous unsuccessful efforts to demonstrate unmasking of LS in humans are thus likely explained by an insufficient naloxone dose (0.021 mg/kg). However, while LS was consistently demonstrated in 21/24 mice, LS was only seen in 4/12 subjects. This difference is likely due to selection bias since the C57BL/6 mouse strain exhibits markedly enhanced pain sensitivity in assays of acute thermal nociception. Future exploratory studies in humans should prioritize inclusion of “high-sensitizers” prone to develop LS and use post-surgical models to elucidate markers of vulnerability to chronic postsurgical pain., Trial Registration: EudraCT 2012-005663-27.

Opioid antagonists are pharmacological tools applied as an indirect measure to detect activation of the endogenous opioid system (EOS) in experimental pain models. The objective of this systematic review was to examine the effect of mu-opioid-receptor (MOR) antagonists in placebo-controlled, double-blind studies using 'inhibitory' or 'sensitizing', physiological test paradigms in healthy human subjects. The databases PubMed and Embase were searched according to predefined criteria. Out of a total of 2,142 records, 63 studies (1,477 subjects [male/female ratio = 1.5]) were considered relevant. Twenty-five studies utilized 'inhibitory' test paradigms (ITP) and 38 studies utilized 'sensitizing' test paradigms (STP). The ITP-studies were characterized as conditioning modulation models (22 studies) and repetitive transcranial magnetic stimulation models (rTMS; 3 studies), and, the STP-studies as secondary hyperalgesia models (6 studies), 'pain' models (25 studies), summation models (2 studies), nociceptive reflex models (3 studies) and miscellaneous models (2 studies). A consistent reversal of analgesia by a MOR-antagonist was demonstrated in 10 of the 25 ITP-studies, including stress-induced analgesia and rTMS. In the remaining 14 conditioning modulation studies either absence of effects or ambiguous effects by MOR-antagonists, were observed. In the STP-studies, no effect of the opioid-blockade could be demonstrated in 5 out of 6 secondary hyperalgesia studies. The direction of MOR-antagonist dependent effects upon pain ratings, threshold assessments and somatosensory evoked potentials (SSEP), did not appear consistent in 28 out of 32 'pain' model studies. In conclusion, only in 2 experimental human pain models, i.e., stress-induced analgesia and rTMS, administration of MOR-antagonist demonstrated a consistent effect, presumably mediated by an EOS-dependent mechanisms of analgesia and hyperalgesia.

Introduction: Development of secondary hyperalgesia following a cutaneous injury is a centrally mediated, robust phenomenon. The pathophysiological role of endogenous opioid signalling to the development of hyperalgesia is unclear. Recent animal studies, carried out after the resolution of inflammatory pain, have demonstrated reinstatement of tactile hypersensitivity following administration of μ-opioid-receptor-antagonists. In the present study in humans, we analyzed the effect of naloxone when given after the resolution of secondary hyperalgesia following a first-degree burn injury., Methods: Twenty-two healthy volunteers were included in this placebo-controlled, randomized, double-blind, cross-over study. Following baseline assessment of thermal and mechanical thresholds, a first-degree burn injury (BI; 47°C, 7 minutes, thermode area 12.5 cm(2)) was induced on the lower leg. Secondary hyperalgesia areas around the BI-area, and separately produced by brief thermal sensitization on the contralateral thigh (BTS; 45°C, 3 minutes, area 12.5 cm(2)), were assessed using a polyamide monofilament at pre-BI and 1, 2, and 3 hours post-BI. At 72 hrs, BI and BTS secondary hyperalgesia areas were assessed prior to start of a 30 minutes intravenous infusion of naloxone (total dose 21 microg/kg) or placebo. Fifteen minutes after start of the infusion, BI and BTS secondary hyperalgesia areas were reassessed, along with mechanical and thermal thresholds., Results: Secondary hyperalgesia areas were demonstrable in all volunteers 1-3 hrs post-BI, but were not demonstrable at 72 hrs post-burn in 73-86% of the subjects. Neither magnitude of secondary hyperalgesia areas nor the mechanical and thermal thresholds were associated with naloxone-treated compared to placebo-treated subjects., Conclusion: Naloxone (21 microg/kg) did not reinstate secondary hyperalgesia when administered 72 hours after a first-degree burn injury and did not increase BTS-generated hyperalgesia. The negative results may be due to the low dose of naloxone or insufficient tissue injury to generate latent sensitization.

Although a relation between diminished human immunity and stress is well recognized both within the general public and the scientific literature, the molecular mechanisms by which stress alters immunity remain poorly understood. We explored a novel model for acute human stress involving volunteers performing a first-time bungee jump from an altitude of 60 m and exploited this model to characterize the effects of acute stress in the peripheral blood compartment. Twenty volunteers were included in the study; half of this group was pretreated for 3 d with the β-receptor blocking agent propranolol. Blood was drawn 2 h before, right before, immediately after and 2 h after the jump. Plasma catecholamine and cortisol levels increased significantly during jumping, which was accompanied by significantly reduced ex vivo inducibility of proinflammatory cytokines as well as activation of coagulation and vascular endothelium. Kinome profiles obtained from the peripheral blood leukocyte fraction contained a strong noncanonical glucocorticoid receptor signal transduction signature after jumping. In apparent agreement, jumping down-regulated Lck/Fyn and cellular innate immune effector function (phagocytosis). Pretreatment of volunteers with propranolol abolished the effects of jumping on coagulation and endothelial activation but left the inhibitory effects on innate immune function intact. Taken together, these results indicate that bungee jumping leads to a catecholamine-independent immune suppressive phenotype and implicate noncanonical glucocorticoid receptor signal transduction as a major pathway linking human stress to impaired functioning of the human innate immune system.