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VIENNA -- A noninvasive epidermal sampling test could help clinicians differentiate between eczema and psoriasis, researchers said here.

Lesional psoriasis (n=35), eczema (n = 21) and healthy skin (n=23) was sampled by non‐invasive tape‐stripping, followed by protein extraction and quantification, explained Anna Berekmeri, MD, of Leeds University Hospital in England, and colleagues.

Protein expression was then analyzed by liquid chromatography tandem mass spectrometry (LC‐MS‐MS, Orbitrap), they stated in a presentation at the Inflammatory Skin Disease Summit (ISDS).

The researchers reported elevated levels of IL-36-gamma, and that the test demonstrated a specificity of 100% and a sensitivity of 94.44% for a diagnosis of psoriasis. Also, psoriasis patients had elevated levels of IL-8, IL-18, CXCL1, S100A8/9, and HBP2. Additionally, patients with atopic dermatitis had elevated levels of CCL17 (TARC) and CCL27 (CTACK).

By determining levels of IL-36-gamma, a diagnosis can be made without subjecting patients to invasive biopsies, Berekmeri suggested.

"Our take-home message is that IL-36-gamma is an excellent biomarker for psoriatic inflammation," she said.

Eczema and psoriasis represent the most frequent inflammatory skin diseases, and they share morphologic and histologic features, the authors stated.

"Both eczematous and psoriatic inflammatory responses may cause diagnostic problems when lesions are very chronic, in certain anatomical locations such as the hand, flexural areas, and scalp and in atypical presentations," they wrote. "There is an unmet need for the identification of a robust diagnostic algorithm, usable as point of care test to allow accurate diagnosis and stratification into appropriate therapeutic pathways."

"Of course we can always do a skin biopsy, but the patient has to undergo the procedure, the biopsy is costly, and we have to wait weeks for the results," Berekmeri said.

For skin stripping technique, an adhesive disk () is applied to the skin surface for 30 seconds, and corneocytes that are collected from the most superficial layers of the skin are analyzed.

The authors identified a total of 220 proteins by mass spectrometry. Compared with healthy samples, 78 proteins showed significantly different expression in psoriasis, while 45 proteins in eczema. When comparing the two disease entities, 18 epidermal proteins had significantly different expression in psoriasis compared to eczema, they noted.

"Using these data, we are able to use a combination of differentially regulated proteins as highly sensitive and selective discriminators of psoriasis from eczema, even in clinically atypical cases," they stated.

They concluded that "the combined detection of disease biomarkers from quantitative proteomic analysis of non‐invasive epidermal sampling, has great potential for disease endotyping, treatment profiling and non‐invasive follow up of therapeutic responses."

ISDS attendee Emma Guttman-Yassky, MD, PhD, of the Icahn School of Medicine at Mount Sinai in New York City, commented that to be confident in the results "we really need to compare these resulted with biopsy."

Berekmeri concurred that biopsy is "the gold standard," but said the biomarkers did appear robust enough on their own to suggest they could be used clinically.

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