Unmet Medical Needs in Chronic, Non-communicable Inflammatory Skin Diseases

Abstract

An estimated 20-25% of the population is affected by chronic, non-communicable inflammatory skin diseases. Chronic skin inflammation has many causes. Among the most frequent chronic inflammatory skin diseases are atopic dermatitis, psoriasis, urticaria, lichen planus, and hidradenitis suppurativa, driven by a complex interplay of genetics and environmental factors. Autoimmunity is another important cause of chronic skin inflammation. The autoimmune response may be mainly T cell driven, such as in alopecia areata or vitiligo, or B cell driven in chronic spontaneous urticaria, pemphigus and pemphigoid diseases. Rare causes of chronic skin inflammation are autoinflammatory diseases, or rheumatic diseases, such as cutaneous lupus erythematosus or dermatomyositis. Whilst we have seen a significant improvement in diagnosis and treatment, several challenges remain. Especially for rarer causes of chronic skin inflammation, early diagnosis is often missed because of low awareness and lack of diagnostics. Systemic immunosuppression is the treatment of choice for almost all of these diseases. Adverse events due to immunosuppression, insufficient therapeutic responses and relapses remain a challenge. For atopic dermatitis and psoriasis, a broad spectrum of innovative treatments has been developed. However, treatment responses cannot be predicted so far. Hence, development of (bio)markers allowing selection of specific medications for individual patients is needed. Given the encouraging developments during the past years, we envision that many of these challenges in the diagnosis and treatment of chronic inflammatory skin diseases will be thoroughly addressed in the future.

Keywords: alopecia areata; atopic dermatitis; chronic spontaneous urticaria; hidradenitis suppurativa; inflammation; medical need; psoriasis; skin.

Figure 1

Clinical images of patients with chronic skin inflammatory diseases. (A) Blurry erythema and lichenification at the inside the bend of the elbows and arms of a patient with atopic dermatitis. (B) Sharply demarked, scaling, erythematous plaques at the back of a patient with psoriasis vulgaris. (C) Generalized erythema and scaling in a patient with psoriasis. (D) Erythematous nodules, partially excoriated, in a patient with prurigo nodularis. (E) Erosions of the lower gums in a patient with mucosal lichen planus. (F) Polygonal, scaling, reddish-violet plaques at the wrist of a patient with cutaneous lichen planus. (G) Scaring, nodules and pustules located at the sub-axillary region of a patient with hidradenitis suppurativa. (H) Sharply demarked hair loss at the back of the head in a patient with alopecia areata. (I) Sharpley demarked white maculae at the hands of a patient with vitiligo. (J) Wheals at the back of a patient with chronic spontaneous urticaria. (K) Brown macules and erosions at the back of a patient with muco-cutaneous pemphigus vulgaris. (L) Tense blisters on erythematous skin on the legs of a patient with bullous pemphigoid. (M) Oral erosions in a patient with mucous membrane pemphigoid. (N) Tense blisters on erythema on the arm of a patient with inflammatory/non-mechano-bullous epidermolysis bullosa acquisita. (O) Tense blister and scaring on the hand of a patient with predominant mechano-bullous epidermolysis bullosa acquisita. (P) Wheals at the leg of a patient with cryopyrin-associated periodic syndrome. (Q) Urticarial exanthema at the lower back of a patient with Schnitzler's syndrome. (R) Alopecia and erythema at the head of a patient with cutaneous lupus erythematosus. (S) Erythema and depigmentation at the arm of a patient with cutaneous lupus erythematosus. (T) Gottron papules in a patient with dermatomyositis. (U) Shortening of the sublingual frenulum in a patient with systemic sclerosis. (V) Raynaud's phenomenon (anemic color of the fingers) and necrosis of the index finger in a patient with systemic sclerosis.