Inflammatory skin diseases: Do current diagnoses do justice to their diversity?

Based on the immune cells involved in the inflammatory reaction, phenotypic differences occur. For optimal therapy, factors must be taken into account to treat the diseases’ subgroups

New diagnostic schemes available to decipher the individual phenotype mosaic and immune response

Inflammatory skin diseases can be classified into individual subgroups according to various criteria (psoriatic, lichenoid, eczematous). Based on the immune cells involved in the inflammatory reaction, phenotypic differences are a result. For optimal therapy, however, even more, factors must be taken into account.

Depending on the T-cells/inflammatory mediators involved in the immune reaction and the epidermal layer affected by it, the inflammatory skin diseases can be divided into four patterns:

Due to the wide range of available examination methods (Western blot, microarray, single-cell sequencing, RNA sequencing, spatial transcriptomics, etc.) and the resulting specification of the individual forms of the disease, treatment can be more targeted today. However, not every disease can be targeted to the same extent.

Most drugs currently available are for the treatment of psoriatic disease forms (infliximab, adalimumab, etanercept, certolizumab, ustekinumab, etc.) There are also effective treatment options for blistering (rituximab) and eczematous (dupilumab) skin diseases. In contrast, there are no proven effective treatment options for granulomatous, fibrous, and lichenoid diseases.

High heterogeneity in the appearance and severity of the individual diseases

In addition to the differences at the cellular level, there are also enormous differences in the phenotypic expression and morphology between the individual inflammatory skin diseases. For example, atopic eczema does not manifest itself in the same way in every affected person.

A cluster study by the Karolinska Institute (Sweden) over the last five years has shown that, in addition to the basic patterns (based on the immune reaction mechanism), many individual patterns that deviate from these basic patterns also exist. For this purpose, in addition to the underlying diagnosis, more than one hundred parameters such as age, sex, histology, morphology, and severity of skin lesions and a detailed anamnesis were collected for precise characterization.

Individual “fingerprinting” for each disease

The conclusion to be drawn from this is that ideally, an individual fingerprint should be created for each patient for his or her existing basic illness, taking into account as many attributes as possible, in order to be able to draw up an optimal treatment plan. In order to be able to implement this in everyday clinical practice, new technical aids - such as appropriate apps - for digital recording and analysis of the image material should also be included.

The overriding goal is the creation of diagnostic algorithms and the detection of biomarkers in order to further optimize the diagnosis of inflammatory skin diseases.

Prof. Dr. Kilian Eyerich, Clinical Centre of the Technical University of Munich - Clinic, and Polyclinic for Dermatology and Allergology at Biederstein, "Inflammatory skin diseases: in between tradition and molecular deciphering", EADVirtual 2020, 29.10.2020.