Evaluation of risk in chronic cutaneous inflammatory conditions for malignant transformation.

Skin carcinomas are the most common form of cancer, and every year thousands of people die from skin cancer-related malignancies. Chronic inflammation is linked to the development and progression of cancer in multiple organ systems - about 20% of all human cancers are a result of chronic inflammation - skin included. While acute inflammation under normal circumstances is a mechanism for host defence and tissue regeneration following insult by trauma or infection by pathogens, over the long term it can drive oncogenic transformation of epithelial cells and promote cancer development, growth and metastasis. Therefore, inflammatory conditions may put individuals at a higher risk to developing skin malignancies. Many skin conditions are characterized by chronic inflammatory processes. These conditions may be particularly susceptible to malignant transformation and predispose patients to develop skin malignancies. As more pathophysiology of chronic inflammatory skin conditions is unveiled, we find that many of these conditions are characterized by immune dysregulation and signalling that result in chronic activation and upregulation of pro-inflammatory chemokines and cytokines, leading to downstream processes that further exacerbate inflammatory processes and cause abnormal cell growth and apoptosis. Here, we review the major chronic cutaneous inflammatory diseases that may have an increased risk of skin malignancies, including atopic dermatitis, psoriasis, discoid lupus erythematosus, lichen planus, hidradenitis suppurativa, prurigo nodularis, lichen sclerosus, systemic sclerosis and morphea, chronic leg ulcers, seborrheic keratoses and basal cell carcinoma. We evaluate the evidence for increased incidence and prevalence, the risk factors associated, the populations at heightened risk and the best management practices.