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IL17A mRNA Staining Distinguishes Palmoplantar Psoriasis from Hyperkeratotic Palmoplantar Eczema in Diagnostic Skin
Jennifer S Chen1, Michael J Murphy1, Katelyn Singh1
1Department of Dermatology, Yale School of Medicine, New Haven, Connecticut, USA.
Abstract:
Acral dermatoses, including hyperkeratotic palmoplantar eczema (HPE), palmoplantar psoriasis (PP), and mycosis fungoides palmaris et plantaris (MFPP), can be challenging to diagnose clinically and histopathologically. In this setting, cytokine biomarkers may be able to help provide diagnostic clarity. Therefore, we evaluated IL-17A, IFN-γ, and IL-13 expression in PP, HPE, and MFPP and compared their expression profiles with nonacral sites. We used biopsy specimens from the Yale Dermatopathology database, selecting cases of HPE (n = 12), PP (n = 8), MFPP (n = 8), normal acral skin (n = 9), nonacral eczema (n = 10), and nonacral psoriasis (n = 10) with classic clinical and histopathologic features. IL17A mRNA expression by RNA in situ hybridization differentiated PP (median score 63.1 [interquartile range 9.4-104.1]) from HPE (0.8 [0-6.0]; P = 0.003), MFPP (0.6 [0-2.6]; P = 0.003), and normal acral skin (0 [0-0]; P < 0.001). Unexpectedly, both PP and HPE showed co-expression of IFNG and IL13 mRNA. In contrast, nonacral psoriasis and eczema showed divergent patterns of IFNG and IL13 mRNA expression. Taken together, we show that IL17A mRNA expression may be a useful biomarker of PP, and we further show that acral dermatoses exhibit distinct immunology compared to nonacral sites, with implications for clinical management.
Insights
Interleukin-17A (IL-17A) mRNA expression can help differentiate palmoplantar psoriasis (PP) from other acral dermatoses. Acral skin conditions show unique immune profiles compared to nonacral sites.
Area of Science:
- Dermatology
- Immunology
- Molecular Biology
Background:
- Acral dermatoses like hyperkeratotic palmoplantar eczema (HPE), palmoplantar psoriasis (PP), and mycosis fungoides palmaris et plantaris (MFPP) present diagnostic challenges.
- Cytokine biomarkers offer potential for improved diagnostic clarity in these conditions.
Purpose of the Study:
- To evaluate the expression of IL-17A, IFN-γ, and IL-13 in PP, HPE, and MFPP.
- To compare the cytokine expression profiles of acral dermatoses with nonacral skin conditions.
Main Methods:
- Analysis of biopsy specimens from patients with HPE, PP, MFPP, normal acral skin, nonacral eczema, and nonacral psoriasis.
- RNA in situ hybridization was used to quantify mRNA expression of IL17A, IFNG, and IL13.
Main Results:
- IL17A mRNA expression significantly differentiated PP from HPE, MFPP, and normal acral skin.
- Both PP and HPE exhibited co-expression of IFNG and IL13 mRNA, unlike nonacral psoriasis and eczema which showed divergent patterns.
- Acral dermatoses displayed distinct immunological profiles compared to their nonacral counterparts.
Conclusions:
- IL17A mRNA expression may serve as a valuable biomarker for diagnosing PP.
- The distinct immunology of acral dermatoses compared to nonacral sites has implications for clinical management.
