What is psoriasis in the skin?

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Last updated: March 24, 2025View editorial policy

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From the Guidelines

Psoriasis is a chronic inflammatory skin disease characterized by well-demarcated, red plaques with silvery scale, commonly involving the scalp, elbows, knees, and presacral region, as described in the joint AAD-NPF guidelines of care for the management and treatment of psoriasis 1.

Key Characteristics of Psoriasis

  • Chronic inflammatory skin disease
  • Well-demarcated, red plaques with silvery scale
  • Commonly involves the scalp, elbows, knees, and presacral region
  • Can involve any area of skin, including the palms, soles, nails, and genitalia

Severity of Psoriasis

  • Defined in part by the total body surface area (BSA) involved
  • Less than 3% BSA considered mild, 3% to 10% BSA considered moderate, and greater than 10% considered severe disease
  • Can be severe irrespective of BSA, when it has serious emotional consequences or when it occurs in select locations, including the hands, feet, scalp, face, genital area, or when it causes intractable pruritus, as noted in the study published in the Journal of the American Academy of Dermatology 1

Pathophysiology of Psoriasis

  • Inflammatory, immune-mediated condition involving cutaneous T-cells, dendritic cells, and keratinocytes
  • Subsequent release of a variety of cytokines and other soluble mediators
  • Keratinocyte hyperproliferation manifesting as characteristic scaly plaques
  • Augmented inflammation underlying a number of systemic disease associations, including metabolic syndrome, cardiovascular disease, and psoriatic arthritis, as discussed in the joint AAD-NPF guidelines of care for the management and treatment of psoriasis 1

From the FDA Drug Label

Methotrexate is indicated in the symptomatic control of severe, recalcitrant, disabling psoriasis that is not adequately responsive to other forms of therapy, but only when the diagnosis has been established, as by a biopsy and/or after dermatologic consultation

  • Psoriasis is a skin condition characterized by severe, recalcitrant, and disabling symptoms.
  • The exact definition of psoriasis in the skin is not explicitly stated, but it is implied to involve severe symptoms that are not adequately responsive to other forms of therapy.
  • A biopsy and/or dermatologic consultation may be necessary to establish the diagnosis of psoriasis 2.

From the Research

Definition of Psoriasis

  • Psoriasis is a chronic autoimmune skin condition characterized by the rapid and excessive growth of skin cells, leading to the formation of thick, red, and scaly patches on the surface of the skin 3.
  • It is a disease of immunological origin that damages the skin and mucous membranes 4.
  • Psoriasis is a chronic inflammatory skin disease identified by the appearance of erythematous, clearly demarcated, scaly plaques 5.
  • It is a systemic immune-mediated disease characterized by development of erythematous, indurated, scaly, pruritic and often painful skin plaques 6.

Characteristics of Psoriasis

  • The rapid turnover of cells is responsible for the dry scaly patches seen clinically, also called plaque type of psoriasis 5.
  • Psoriasis is divided into various kinds: plaque, nail type, guttate, or inverse, also pustular 5.
  • The most commonly occurring type of psoriasis is plaque psoriasis, seen with itchy, dry, scales covering patches of skin that are raised 5.
  • Psoriasis pathogenesis is driven by proinflammatory cytokines and is associated with increased risk for comorbidities 6.

Effects of Psoriasis on the Skin

  • Psoriasis leads to the formation of thick, red, and scaly patches on the surface of the skin 3.
  • The patches can be itchy and painful, and may cause discomfort for patients affected by this condition 3.
  • Psoriasis damages the skin and mucous membranes 4.
  • The disease is characterized by development of erythematous, indurated, scaly, pruritic and often painful skin plaques 6.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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