Prurigo nodularis in HIV-infected individuals

Prurigo Nodularis: Pathogenesis and the Horizon of Potential Therapeutics

Chronic pruritus that lasts for over 6 weeks can present in various forms, like papules, nodules, and plaque types, with prurigo nodularis (PN) being the most prevalent. The pathogenesis of PN involves the dysregulation of immune cell-neural circuits and is associated with peripheral neuropathies, possibly due to chronic scratching. PN is a persistent and challenging condition, involving complex interactions among the skin, immune system, and nervous system. Lesional skin in PN exhibits the infiltration of diverse immune cells like T cells, eosinophils, macrophages, and mast cells, leading to the release of inflammatory cytokines and itch-inducing substances. Activated sensory nerve fibers aggravate pruritus by releasing neurotransmitters, perpetuating a vicious cycle of itching and scratching. Traditional treatments often fail, but recent advancements in understanding the inflammatory and itch transmission mechanisms of PN have paved the way for innovative therapeutic approaches, which are explored in this review.

Incident Comorbidity, Resource Use, and All-Cause Mortality Associated with Prurigo Nodularis: A United Kingdom Retrospective Database Analysis

We described comorbidity, resource utilization, and mortality for patients with prurigo nodularis (PN) using data from the Clinical Practice Research Datalink. Patients with incident PN (2008-2018) were selected and matched to controls. Of 2,416 patients with PN, 2,409 (99.7%) were matched to controls. Prevalence of atopic dermatitis (relative risk [RR] = 2.571; 95% confidence interval [CI] = 2.356-2.806), depression (RR = 1.705; 95% CI = 1.566-1.856), anxiety (RR = 1.540; 95% CI = 1.407-1.686), coronary heart disease (RR = 1.575; 95% CI = 1.388-1.787), chronic kidney disease (RR = 1.529; 95% CI = 1.329-1.759), and type 2 diabetes mellitus (RR = 1.836; 95% CI = 1.597-2.111) was significantly higher for patients with PN. Subsequent risk of atopic dermatitis (hazard ratio = 6.58; 95% CI = 5.17- 8.37), depression (hazard ratio = 1.61; 95% CI = 1.30-1.99), and coronary heart disease (hazard ratio = 1.37; 95% CI = 1.09-1.74) were significantly increased. Resource utilization was increased in all settings: incidence rate ratio = 1.48 (95% CI = 1.47-1.49) for primary care, incident rate ratio = 1.80 (95% CI = 1.75-1.85) for inpatients, incident rate ratio = 2.15 (95% CI = 2.13-2.18) for outpatients, and incidence rate ratio = 1.32 (95% CI = 1.27-1.36) for accident and emergency. Respective cost ratios were 1.78 (95% CI = 1.67-1.90), 1.52 (95% CI = 1.20-1.94), 2.34 (95% CI = 2.13-2.58), and 1.55 (95% CI = 1.33-1.80). Total primary and secondary healthcare costs were £2,531 versus £1,333, a cost ratio of 1.62 (95% CI = 1.36-1.94). The adjusted hazard ratio for mortality was 1.37 (95% CI = 1.14-1.66). Patients with PN had significantly increased rates of comorbidity, healthcare resources utilization, and mortality compared with matched controls.

Serum IgG and lymphocyte counts are useful for the early detection of infection in patients receiving bendamustine-rituximab therapy

Bendamustine-rituximab (BR) therapy has been established as a highly effective regimen for indolent non-Hodgkin lymphoma (NHL). However, patients who receive BR therapy exhibit persistent hypogammaglobulinemia and lymphopenia, resulting in an increased incidence of infections. As a sustained immunosuppressive state is a risk factor for infections, early predictive biomarkers for infections related to BR therapy need to be identified. We retrospectively analyzed 61 patients with indolent NHL who were followed up for 2 years after the end of BR therapy. Progression-free survival was significantly influenced by the incidence of infections. Patients with infections related to BR therapy exhibited persistent hypogammaglobulinemia and lymphopenia. In addition, we determined the cutoff values of serum IgG values and lymphocyte counts for infections using receiver operating characteristic curve analysis. Minimum serum IgG and lymphocyte counts at the first BR treatment cycle were significantly associated with the incidence of infections during and after BR treatment. Furthermore, the development of skin reactions during BR therapy was significantly associated with the incidence of infections after BR therapy. Our study suggested that these values and symptom are predictive biomarkers for infections related to BR therapy. Based on these findings, better management of indolent NHL patients will be possible.

Association of prurigo nodularis and infectious disease hospitalizations: a national cross-sectional study

BACKGROUND

Prurigo nodularis (PN) is associated with a variety of systemic comorbidities, including infectious diseases such as HIV and viral hepatitis. There are limited data on other infectious disease comorbidities in patients with PN.

AIM

To characterize infectious disease hospitalizations among patients with PN and the associated cost burden.

METHODS

We searched the 2016-2017 National Inpatient Sample, a cross-sectional sample of 20% of all US hospitalizations, for infectious disease hospitalizations among patients with PN. Associations of PN with infections and related costs were determined using multivariable logistic and linear regression, adjusting for age, race, sex and insurance type.

RESULTS

PN was associated with any infection overall (OR = 2.98, 95% CI 2.49-3.56), and with HIV, cutaneous, hepatobiliary, central nervous system, bacterial, viral and fungal/parasitic infections and for sepsis. Patients with PN had a higher mean cost of care (US$11 667 vs. US$8893, P < 0.001) and length of stay (5.5 vs. 4.2 days, P < 0.001) for any infection overall and for 7 of 13 other infections. Adjusting for age, race, sex and insurance coverage, PN was associated with higher cost (+30%, 95% CI +17 to +44%) and higher length of stay (+30%, 95% CI +18 to +44%) for any infection overall, and for several specific infections. These associations remained with alternate regression models adjusting for severity of illness.

CONCLUSION

There is a high infectious disease burden among patients with PN, corresponding to higher healthcare utilization and spending. Clinicians must be aware of these associations when treating these patients with immunomodulatory drugs.

Pathophysiology, diagnosis, and pharmacological treatment of prurigo nodularis

Introduction: Prurigo nodularis (PN) is a chronic inflammatory skin disease characterized by intensely pruritic, hyperkeratotic nodules distributed on the trunk and extensor surfaces of the extremities. PN has a profoundly negative impact on sleep and quality of life in patients with PN. There are currently no U.S. Food and Drug Administration-approved agents and patients are often recalcitrant to current therapies, highlighting the importance of further research into this severely debilitating condition. Areas covered: A PubMed search was conducted to find available literature on the pathophysiology and clinical management of PN. In this review article, we discuss the current understanding of the pathophysiology, recommended diagnostic approach, and treatment options available for PN. Expert opinion/commentary: PN is an extremely difficult condition to treat, because there is a lack of effective therapies available due to our limited understanding of its pathophysiology. Currently, available treatment options are often multimodal due to the intersection of neuroimmune etiologic factors in the pathogenesis of PN. Fortunately, as our knowledge of PN expands, novel treatments targeting specific molecular biomarkers of PN are emerging, providing hope to this long-suffering patient population.

Prurigo nodularis: Epidemiology and clinical features

Prurigo nodularis (PN) is a chronic inflammatory skin disease characterized by intensely pruritic, hyperkeratotic nodules that favor the extensor surfaces of the extremities and the trunk. In addition to its significant impact on quality of life, many patients with PN are recalcitrant to therapy because there are currently no therapies approved by the US Food and Drug Administration. In the first article of this 2-part continuing medical education series, we describe the broader epidemiology, patient demographics, physical examination findings, and symptoms to aid in the timely recognition and diagnosis of PN. Furthermore, we quantify the burden of comorbidities in PN by discussing the broad spectrum of systemic diseases and mental health conditions that have been associated with this condition. The second article of this 2-part series focuses on the pathogenesis of PN and provides detailed algorithms for comprehensive work-up and management.

Association between Prurigo Nodularis and Etiologies of Peripheral Neuropathy: Suggesting a Role for Neural Dysregulation in Pathogenesis

Background: Prurigo nodularis (PN) is an intensely pruritic skin condition of considerable morbidity. However, the pathogenesis of PN and its association with underlying neuropathy is unclear. Objective: We sought to investigate the association between PN and etiologies of peripheral neuropathy. Methods: A cross-sectional analysis of adult patients (≥18-year-old) with PN, AD, and Psoriasis at the Johns Hopkins Health System over a six-year period (January 2013–January 2019) was performed. The strength of association with etiologies of peripheral neuropathy were compared to a control cohort of individuals without PN, as well as those with AD or psoriasis. Results: A total of 1122 patients with PN were compared to 10,390 AD patients, 15,056 patients with psoriasis, and a control cohort of 4,949,017 individuals without PN, with respect to 25 comorbidities associated with peripheral neuropathies. Limitations: Comparisons between peripheral neuropathies and PN represent associations but are not causal relationships. Conclusion: Prurigo nodularis is strongly associated with peripheral neuropathies, suggesting a role for neural dysregulation in pathogenesis.

Diagnostic Workup and Evaluation of Patients with Prurigo Nodularis

Prurigo nodularis (PN) is a chronic inflammatory skin disease characterized oftentimes by symmetrically distributed, severely pruritic nodules. Currently, the pathophysiology of PN remains to be fully elucidated, but emerging evidence suggests that neuroimmune alterations play principal roles in the pathogenesis of PN. There are several associated etiologic factors thought to be associated with PN, including dermatoses, systemic, infectious, psychiatric, and neurologic conditions. We conducted a systematic literature review to evaluate the clinical presentation, diagnosis, and etiologic factors of PN. In this review, we discuss common differential diagnoses of PN and recommend an evidence-based, standardized diagnostic evaluation for those with suspected PN.

Pruritus in allergy and immunology

Although evolutionarily conserved to expel ectoparasites and aid in the clearance of toxins and noxious environmental stimuli from the host, the type 2 immune response can become pathologic in the setting of a variety of allergic disorders. Itch can be a behavioral extension of type 2 immunity by evoking scratching and, in the setting of disease, can become chronic and thus highly pathologic as well. Classically, our understanding of itch mechanisms has centered around the canonical IgE-mast cell-histamine axis. However, therapies aimed at blocking the histaminergic itch pathway have been largely ineffective, suggesting the existence of nonhistaminergic itch pathways. Indeed, recent advances in itch biology have provided critical new insight into a variety of novel therapeutic avenues for chronic itch in the setting of a number of allergic disorders. Here we highlight how these new developments will likely inform the problem of pruritus in a variety of well-established and emerging conditions in the field of allergy.

Inflammatory dermatoses in human immunodeficiency virus

Various inflammatory dermatoses have been described in association with human immunodeficiency virus (HIV) infection. These either present in the usual way or in varied atypical presentations. This article gives a brief review about the etiopathogenesis and clinical presentation of the common inflammatory dermatoses associated with HIV such as psoriasis, reactive arthritis, seborrheic dermatitis, eosinophilic folliculitis, pruritic papular eruption, photosensitivity disorders prurigo nodularis, atopic dermatitis, and ichthyosis.

Increased number of peripheral CD8+ T cells but not eosinophils is associated with late-onset skin reactions caused by bendamustine

Bendamustine is a chemotherapeutic drug that has recently come to be used frequently in the treatment of indolent B cell lymphomas. Skin toxicity is recognized as one of its characteristic side effects, but detailed information on such reactions has not yet been obtained. To clarify the clinical features of skin toxicity associated with bendamustine, we retrospectively analyzed skin reactions that developed in patients treated with bendamustine and rituximab (BR). Of 34 patients treated with 3-6 cycles of BR, 11 developed late-onset, persistent skin eruptions. These patients demonstrated increases in CD8(+) T cell number and CD8(+):CD4(+) cell ratio at the end of chemotherapy. In contrast, peripheral eosinophil count was not associated with such adverse events, whereas eosinophil infiltration was frequently observed in the skin. Patients with skin reactions tended to have higher seropositivity of hepatitis B core antibody, and multiplex viral screening PCR of the frozen sera demonstrated cytomegalovirus-DNA in some of the eruption-positive patients. It is speculated that inappropriate activation of CD8(+) T cells by latently infected pathogens may be one of the triggers of late-onset skin reactions caused by bendamustine.

Prurigo nodularis in a 9-year-old girl

A 9-year-old African-American female with a known history of atopic dermatitis presented for evaluation of an intensely pruritic nodular rash on both upper and lower extremities, buttocks, and lower abdomen for more than 1 year. The patient had been treated with several medium-potency topical steroids and antipruritics without appreciable improvement. After considering and excluding other differential diagnoses, the diagnosis of prurigo nodularis (PN) in association with atopic dermatitis was made. Prurigo nodularis usually occurs in middle-aged and older persons and is rarely seen in the pediatric population. The onset of PN in the case presented is considerably earlier than what has been described in literature. The etiology of the disorder is unknown. The management of prurigo nodularis is usually challenging for both patients and treating physicians. Frequently, combinations of several medications or modalities are used in an attempt to control disease activity. Overall, PN is a benign condition in children, particularly when it is associated with atopic dermatitis. It does not increase mortality; however, it can cause significant morbidity in untreated patients.

Prurigo nodularis: A review

Prurigo nodularis is a chronic condition characterized by a papulonodular pruriginous eruption of unknown aetiology. This condition is a difficult disease to treat and causes frustration to both the patient and the treating doctor. A variety of systemic conditions have been reported to be associated with prurigo nodularis. The mechanism by which these disorders may trigger prurigo nodularis is unknown. Nerve growth factor has been implicated in the pathogenesis of prurigo nodularis. Calcitonin gene-related peptide and substance P immunoreactive nerves are markedly increased in prurigo nodularis when compared with normal skin. These neuropeptides may mediate the cutaneous neurogenic inflammation and pruritus in prurigo nodularis. Topical or intralesional glucocorticoids are the treatment of choice. Other topical treatments such as topical vitamin D3, and topical capsaicin have also been reported to be effective. Oral treatments such as cyclosporin and thalidomide have been shown to improve both appearance of the skin and pruritus. We review the clinical features, associations, pathology, pathogenesis and treatment of prurigo nodularis.

Dermatologie an der Universitatsklinik Mbarara, Uganda. Dermatology at the University Hospital of Mbarara, Uganda

The Georg Klingmüller Clinic is part of Mbarara University Teaching Hospital (MUST) in south-western Uganda. Established in 1999, this clinic cares for about 6,000 dermatological patients per year. We review the disease spectrum, available diagnostic tools, and therapeutic options in this clinic. In addition, the importance of dermatology for the fight against HIV/AIDS is discussed with respect to the socio-economic background of a sub-Saharan country. Co-operation with dermatology departments in Germany may not only help to diagnose skin diseases in Mbarara, but may also be valuable for the visiting dermatologist to manage the increasing numbers of patients with dark skin at home.