Higher Expression of Lympho-epithelial Kazal-type-Related Inhibitor-1 Fragments and Decreased Desquamation in the Lesional Skin of Nummular Eczema

Nummular eczema, a chronic dermatitis characterized by coin-shaped lesions, was first documented in 1857. However, its pathophysiological characteristics are still not well known. To investigate differences in the regulation of the desquamation process in the stratum corneum of lesional and nonlesional skin of patients with nummular eczema and healthy control subjects, tape-stripped stratum corneum samples from patients with nummular eczema and healthy volunteers were analysed using immunofluorescence staining and western blot analysis. In the nummular eczema lesional skin, expression of desmoglein-1, desmocollin-1, and corneodesmosin exhibited a disorganized, dense or partially diffuse non-peripheral pattern with increased intensity, compared with the peripheral patterns observed in healthy or nonlesional skin, suggesting the impaired desquamation process in nummular eczema. Furthermore, although the expression of the desquamation-related serine proteases, kallikrein-related peptidase 7 and 5, was increased in nummular eczema lesional skin, the immunofluorescence staining of lympho-epithelial Kazal-type-related inhibitor-1, an endogenous inhibitor of various kallikrein-related peptidases, and its fragments were significantly increased in the nummular eczema lesional skin, suggesting its contribution to the inhibition of corneodesmosomal degradation. Therefore, the increased detection of corneodesmosomal proteins in nummular eczema lesions may be due to the increased amount of the fragments of lympho-epithelial Kazal-type-related inhibitor-1, which could contribute to delayed desquamation.

The neglected twin: nummular eczema is a variant of atopic dermatitis with co-dominant Th2/Th17 immune response

BACKGROUND

Nummular eczema (NE) is a common chronic inflammatory skin disease characterized by multiple, pruritic, discoid-shaped lesions. Since the underlying immune mechanisms are not fully understood, it is unclear whether NE should be regarded as variant of atopic dermatitis (AD) or a distinct disease.

OBJECTIVE

Here, we compared the clinical, histopathological, and molecular signature of NE with that of type 2 and type 3 skin diseases.

METHODS

We performed bulk RNAseq, histological and clinical studies in lesional and non-lesional skin biopsy specimens from NE (n=50), AD (n=47) and psoriasis (n=90) patients.

RESULTS

NE displayed typical hallmarks of AD such as an impaired epidermal barrier, microbial colonization, spongiosis and eosinophil infiltration, but also aspects of psoriasis including increased epidermal thickness, number of Ki67⁺ cells and neutrophilic infiltration. On gene expression level, neutrophil-attracting cytokines (IL19, CXCL8, CXCL5) were upregulated while Th2-related cytokines (IL13, CCL17, CCL18, CCL26, CCL27) were similar expressed in NE compared to AD. Principal component analysis of transcriptome data from lesional skin showed that AD and NE cluster together distinct of psoriasis. In line with this, an established molecular classifier identified NE as AD rather than psoriasis. Finally, we demonstrated clinical and molecular efficacy of Dupilumab treatment in NE.

CONCLUSION

In summary, NE shows overlapping type 2 and type 3 immune signatures, while type 2 immunity is dominating and should be the primary target of specific therapeutic interventions. This supports the view of NE as a variant of AD.

Prevalence and trend of allergen sensitization in patients with nummular (discoid) eczema referred for patch testing: North American Contact Dermatitis Group data, 2001-2016

BACKGROUND

Few studies have examined the relationship between nummular (discoid) eczema (NE) and allergic contact dermatitis (ACD).

OBJECTIVE

To examine trends, associations, and clinical relevance of ACD in patients with NE who were referred for patch testing.

METHODS

Retrospective analysis of 38 723 patients from the North American Contact Dermatitis Group.

RESULTS

Overall, 748 patients (1.9%) were diagnosed with NE; 23.9% had a concomitant diagnosis of ACD. The prevalence of NE fluctuated over time between 2001 and 2016, with no overall change in prevalence in diagnosed NE. In multivariable logistic regression models, NE increased steadily with age and was associated with male sex and Asian and other race/ethnicity, and inversely associated with a history of atopic dermatitis (AD) and hay fever. Patients with NE had lower proportions of one or more positive allergic reactions and lower odds of a positive reaction in multiple individual allergens. The most commonly relevant allergens in patients with NE were formaldehyde 2.0% aq., methylisothiazolinone, quaternium 15, fragrance mix I, and propylene glycol.

CONCLUSION

NE is a heterogeneous disorder with distinct subsets of lesional distributions and a profile of relevant allergens, especially formaldehyde and formaldehyde releasers. Nearly one in four patients with NE had ACD, supporting the role of patch testing in patients with NE.

Effectiveness of dupilumab for the treatment of nummular eczema phenotype of atopic dermatitis in adults

Nummular eczema (NE) is currently considered as one of the clinical phenotypes of atopic dermatitis (AD) of the adult. In this multicentre study, 30 adult patients (age ≥ 18 years) affected with nummular-like AD were treated with dupilumab, a monoclonal antibody against the receptor for interleukin(IL)-4 and IL-13. The evaluation of the results after 16 weeks of treatment showed a significant improvement of the disease, as demonstrated by reduction in Eczema Area Severity Score (EASI), visual analogue score (VAS) of pruritus, and Dermatology Life Quality Index (DLQI) scores. Conjunctivitis in one patient was the only side effect. In conclusion, dupilumab seems to be an effective and safe treatment in NE phenotype of AD of the adult.

Methotrexate for severe nummular eczema in children: Efficacy and tolerability in a retrospective study of 28 patients

BACKGROUND/OBJECTIVES

Nummular eczema in children is a chronic condition characterized by pruritic coin-shaped eczematous lesions that affect any part of the body and often become exudative. Mid- to high-potency topical corticosteroids are considered the mainstay treatment, but there are limited data on the use of systemic therapy for nummular eczema in children. The objective of the current study was to evaluate the efficacy and safety of methotrexate in children with severe nummular eczema.

METHODS

A retrospective review was undertaken of children with nummular eczema treated with methotrexate between January 2007 and May 2017.

RESULTS

The records of 28 patients (24 male, 4 female) with a mean age at the beginning of treatment of 7.8 ± 1.6 years (95% confidence interval (CI) = 6.1-9.4 years) were reviewed. The median duration of treatment was 12.6 ± 3.3 months (95% CI = 9.2-16 months), and 14 patients were still undergoing methotrexate therapy at the time of last review. Ten patients (35.7%) had complete or almost complete clearance of eczema (> 90% improvement), 13 (46.4%) had marked improvement (50%-89%), four had mild improvement (< 50%), and one failed methotrexate therapy. Gastrointestinal intolerance (21.4%) and a nonsignificant increase in liver enzymes (17.9%) were the most frequent side effects. No serious adverse events were noted.

CONCLUSION

Methotrexate is an effective, well-tolerated treatment in children with moderate to severe nummular eczema that has failed to respond to conventional topical therapy.