What is Psoriasis? Psoriasis is a chronic autoimmune disease of the skin, causing inflammation of the body. It affects about 3% of the US population. It can manifest at any age, however, there is an increase in incidence between the ages of 18 to 39 and 50 to 69. Psoriasis affects people of all genders and ethnicities.

What causes Psoriasis?


The pathogenesis of psoriasis is not completely understood but thought to be caused by over activation of the immune system and involving T-lymphocytes, dendritic cells, natural killer cells, and cytokines leading to downstream activation of the inflammatory cascade. The increase in inflammation leads to thickening of the skin and irritation. It can also affect other organs and tissues of the body. One of the main pathways implicated is the activation of the TH17 by IL-23.


The risk of developing psoriasis depends on a number of factors. Multiple genes are implicated and there is a higher risk of psoriasis in those who have one or more first-degree relatives have psoriasis. Psoriasis may be exacerbated by trauma to the skin, dermatologic infections, cold weather, smoking, stress, and some medication such as lithium and interferon.


Symptoms of Psoriasis

The symptoms of psoriasis vary by person, type of psoriasis, and severity of the disease. The most common type of psoriasis affecting 80-90% of patients is plaque psoriasis. It manifests as pruritic patches of thick, raised skin, and silvery scaling with sharply defined margins. Plaque psoriasis usually forms on the scalp, elbows, knees, or gluteal cleft, but may be found anywhere on the body. Other types of psoriasis include:


  • Guttate psoriasis.
  • Inverse psoriasis.
  • Pustular psoriasis or palmoplantar pustulosis.
  • Generalized pustular psoriasis, also called Zumbusch psoriasis.
  • Erythrodermic psoriasis.
  • Nail psoriasis.
  • Psoriatic arthritis.


Patients with psoriasis also have a higher risk of coronary artery disease, inflammatory bowel disease, depression, anxiety, and suicidal ideation.


How is Psoriasis treated?

The treatment of psoriasis is determined by the severity of the disease and the presence of comorbid diseases.


Topical treatment options for mild psoriasis:

  • Emollients
  • Corticosteroids
  • Vitamin D analogues
  • Calcineurin inhibitors
  • Keratolytics


Targeted phototherapy may be used alone or in addition to topical treatments.


If topical treatments don’t work, and in moderate-to-severe psoriasis, other options include:

  • Biologics
  • DMARDs
  • UV-B and PUVA phototherapy


Armstrong, A. W., & Read, C. (2020). Pathophysiology, Clinical Presentation, and Treatment of Psoriasis. JAMA, 323(19), 1945.