Psoriasis – Clinical Characteristics, Subtypes, Symptoms, and the Role of an Anti-Inflammatory Diet

Psoriasis is fundamentally a systemic, non-contagious inflammatory disease orchestrated by the IL-23/IL-17 cytokine axis:

• Dendritic cell activation – trigger factors prompt dermal myeloid dendritic cells to secrete interleukin-23 (IL-23), driving the expansion of pathogenic Th17 cells.
• Cytokine storm cascade – Th17 lymphocytes release IL-17A, IL-22, and TNF-alpha, triggering explosive epidermal hyperproliferation and neutrophil microabscess formation (Munro's microabscesses).
• Systemic comorbidities – sustained cytokine circulation heightens long-term risks for metabolic syndrome, coronary atherogenesis, non-alcoholic fatty liver, and major depressive disorder.

The canonical primary dermatological lesion is a sharply demarcated, erythematous infiltrated papule covered with lamellar silvery micaceous scales:

• Stearin candle sign – scratching the surface accentuates glistening wax-like silvery scales.
• Auspitz sign – gentle removal of the adherent scale exposes dilated papillary capillaries, producing pinpoint droplets of hemorrhage.
• Koebner isomorphic phenomenon – emergence of de novo psoriatic plaques at sites of cutaneous mechanical microtrauma (scratches, burns, surgical incisions) within 7–14 days.

Psoriasis exhibits phenotypic heterogeneity across recognized clinical classifications:

• Plaque psoriasis (Psoriasis vulgaris) – accounts for 80–90% of cases, classically distributed over extensor surfaces (elbows, knees, lumbosacral region).
• Scalp psoriasis – sharply bordered, hyperkeratotic plaques without permanent scarring alopecia.
• Psoriatic arthritis (PsA) – afflicts 20–30% of psoriatic patients, presenting peripheral enthesitis, dactylitis (sausage digits), and progressive joint erosions.
• Pustular psoriasis – generalized (von Zumbusch) or localized palmoplantar eruption characterized by sterile subcorneal neutrophilic pustules.
• Nail psoriasis – manifested by thimble-like pitting, subungual hyperkeratosis, and 'oil drop' salmon patches.

Nutritional intervention directly targets systemic inflammatory cytokine cascades and significantly improves Psoriasis Area and Severity Index (PASI) scores:

• Long-chain omega-3 fatty acids (EPA and DHA) – wild oily fish and purified marine oils competitive inhibit arachidonic acid conversion into leukotriene B4 (LTB4), dampening neutrophilic dermal infiltration.
• Mediterranean dietary pattern – high intake of extra virgin olive oil, polyphenolic berries, and brassica greens lowers systemic hs-CRP and TNF-alpha levels.
• Adiposity reduction – visceral adipose tissue serves as an endocrine organ pumping out pro-inflammatory adipokines; caloric restriction and weight loss dramatically enhance clinical responsiveness to systemic biologics.
• Abstinence from alcohol and smoking – ethanol escalates cutaneous microvascular permeability and exacerbates flare-ups; smoking is strongly linked to severe palmoplantar pustulosis.
• Vitamin D3 and antioxidant cofactors – optimizes keratocyte differentiation and normalizes regulatory T-cell (Treg) function.