Keloid: Scar or disease, which is it?

In its simplest form a keloid scar is deemed to be a benign fibroproliferative reticular dermal lesion of unknown aetiopathogenesis found in human skin alone. This lesion may arise following the most innocuous form of cutaneous injury including bites, accidental cuts, piercing and surgery. In keloid prone individuals, a dermal injury will certainly result in an exophytic protuberant growth with persistent and progressive peri-lesional expansile behaviour beyond the site of the original injury. Other skin scar types, however, do not behave in this manner and respond well to monotherapy alone unlike keloids, which often can recur following any form of treatment.

Even though keloids are traditionally viewed as scars on the healing spectrum, keloids are a distinct pathology provoked by cutaneous injury rather than a continuum.   In order to elucidate the aetiopathogenesis of keloids, distinction between a simple cutaneous scar and a disease status must be made.   Therefore, it is plausible to make a link between keloid scars and their quasi-neoplastic tendencies to distinguish them as a disease rather than a scar entity alone. 

In view of this, keloids behave clinically and biologically differently and are quite dissimilar to any other skin scar type. Keloid scars are likened to neoplastic lesions (non-malignant cancer-like tumours) due to their aggressive clinical behaviour, genotypic-phenotypic tissue-characteristics and resistance to treatment. Monotherapy alone is associated with nearly 100% recurrence of keloid scars. Therefore, often the use of combination oncologic therapies such as cryotherapy, chemotherapy and radiotherapy, is required to prevent early recurrence by halting mitosis in different phases of cell cycle and consequently inducing suppression of fibroblast proliferation and disease progression.

The biomarker expression profile in keloid scars and cutaneous neoplastic lesions highlight the striking parallels between keloids and both benign and malignant mesenchymal tumours. In addition, keloids harbour tertiary lymphoid tissue, stain for many inflammatory markers and display a hypoxic micro-environment, containing derived-cells that resemble cancer cell bioenergetics and respond to oncologic therapy. Signalling pathways common to these diseases have been found to guide the matrix composition of keloids as well as neoplastic lesions. 

This concept underscores the need to identify keloids as a disease in order to develop targeted therapy, which can lead to enhanced diagnosis and improved theranosis. In conclusion, keloid scars are the visible end result or cutaneous manifestation of keloid disease. So, clinicians need to be careful and mindful of their management approach in view of the high degree of recurrence and potential exacerbation of clinical signs and symptoms post therapy as a keloid is both a scar and a disease!

Wouldn’t you agree?  

See recent articles published on line by my group on this important topic:

https://www.ncbi.nlm.nih.gov/pubmed/31440236

and

https://www.ncbi.nlm.nih.gov/pubmed/31943508