Unpredictable hypertrophic scarring (HS) occurs after approximately 35% of all surgical procedures and causes significant physical and psychological impacts. Hence, the understanding of mechanisms underlying HS formation is essential, and so is the requirement of a prognostic tool.

The aim of a new study published in Experimental Dermatology was to determine whether (systemic) immunological differences exist between patients who develop HS and those who develop normotrophic scars (NS) and to assess whether those differences can be used to identify patients prone to developing HS.

In this prospective cohort study, participants were categorized into NS and HS groups in which – cytokine release by peripheral blood mononuclear cells (PBMC) and the irritation threshold (IT) after an irritant (sodium lauryl sulphate) patch test were evaluated.

Univariate regression analysis of PBMC cytokine secretion showed that low MCP-1, IL-8, IL-18 and IL-23 levels have a strong correlation with HS. Combinations of two or three cytokines – TNF-a, MCP-1 and IL-23, showed an improved AUC indicating a better correlation with HS than single cytokine analysis. These combination models produce good prognostic results over a broad probability range (sensitivity 93.8%, specificity 86.7% and accuracy 25%). Furthermore, the HS group had a lower IT than the NS group and an accuracy of 68%.

It was inferred that very fundamental immunological differences exist between individuals who develop HS and those who do not. The cytokine assay forms the basis of a predictive prognostic test for HS formation, but the less invasive, easily performed irritant skin patch test is more accessible for daily practice.

Corticosteroid injection is a mainstay of therapy for hypertrophic scars; surgical excision may also be used. Laser therapy including long-pulsed Nd:YAG laser or pulsed dye laser have proven benefit in treating hypertrophic scars. This modality not only improves the color of the scar, but can also reduce the height and tension on the scar. These lasers target blood vessels and are therefore, very helpful in reducing the color changes visible in hypertrophic scars. Cryotherapy is another option in the treatment of hypertrophic scars.

Sources: Experimental Dermatology. 2020 Jul 3. doi: 10.1111/exd.14139.

Schmieder SJ, Ferrer-Bruker SJ. Hypertrophic Scarring. [Updated 2019 Dec 21]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK470176/