A new test can tell the difference between psoriasis and eczema, even when practitioners cannot, according to researchers from Germany.

In patients affected by both psoriasis and eczema simultaneously, a comparison of the molecular signatures of psoriasis and eczema identified genes and signaling pathways common to and exclusive for each disease across all patients, study authors wrote in Science Translational Medicine.

They compared genes from 24 patients aged 18 to 60 years who had either psoriasis or eczema and found that psoriasis resembled a wound-healing reaction with an over-activated immune response in the upper layer of the skin. This process is what causes the characteristic scaly skin markings seen with psoriasis.

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In contrast, the investigators reported that eczema involved other immune cell subtypes that obstructed the skin barrier and blocked the skin’s immune response. Eczema skin reactions were commonly associated with bacteria, viruses, or fungi, which can make inflammation worse.

“In an independent cohort of eczema (n=28) and psoriasis patients (n=25), respectively, this classifier diagnosed all patients correctly and also identified initially misdiagnosed or clinically undifferentiated patients,” the study authors wrote.


  1. Quaranta M. Sci Transl Med. 2014;6:244ra90.