Psoriasis is a systemic chronic skin disorder characterized by excessive keratinocyte proliferation that results into thickened scaly plaques, itching and inflammatory changes in the epidermis and dermis. It is transmitted genetically but can be provoked by environmental factors.
It is found in approximately 2% of the population that primarily affects the skin and joints.
It is associated with other inflammatory disorders and autoimmune diseases (eg psoriatic arthritis, inflammatory bowel disease, coronary artery disease).
Generally, it begins as red scaling papules that coalesce to form round-to-oval plaques. The rashes are often pruritic and may be painful.

Psoriasis Signs and Symptoms


  • Psoriasis vulgaris is a systemic, chronic, inflammatory disorder that can be transmitted genetically and provoked by environmental factors
    • Found in approximately 2% of the population
    • Primarily affects the skin and joints
    • Associated with other inflammatory disorders and autoimmune diseases (eg psoriatic arthritis, inflammatory bowel disease, coronary artery disease)
    • Characterized by recurrent exacerbations and remissions

Signs and Symptoms


  • Begins as red scaling papules that coalesce to form round-to-oval plaques
  • Rashes are often pruritic and may be painful

Plaque Psoriasis

  • Most common form of psoriasis approximately affecting 80-90% of patients
  • Scaling, erythematous, well-demarcated and silvery plaques with various sizes ranging from 1 cm to several cms
  • Plaques are irregular, round to oval in shape and tend to be symmetrically distributed
  • Typically affected areas: Elbows, knees, scalp, trunk, intergluteal cleft, buttocks, soles and palms
    • Occasionally, genitalia may also be affected 
  • Painful fissuring within plaques can occur when lesions are present over joint lines, palms and soles

Guttate Psoriasis

  • Common in persons <30 years old and affects <2% of patients with psoriasis
  • Usually occurs after an upper respiratory infection with group A beta-hemolytic streptococci
  • Teardrop-shaped, salmon-pink papules usually within a fine scale measuring 1-10 mm
  • Usually found on the trunk and proximal extremities
  • May be the first manifestation of psoriasis in a healthy individual or an acute exacerbation of long-standing plaque

Pustular Psoriasis

  • Generalized
    • Also called von Zumbusch psoriasis
    • Characterized by sterile pustules on an erythematous base that cover large portions of the trunk and extremities
    • Pustules may coalesce and form large pools of pus in severe cases
    • Skin’s protective functions are lost and patient is susceptible to infection, loss of fluids and nutrients
    • Uncommon, severe form of psoriasis associated with systemic symptoms (eg fever, malaise); can be life-threatening 
  • Localized
    • Pustules are localized to the palms and soles of the feet; may also localize on top of plaque
    • Not life-threatening but debilitating because of difficulty in using hands or feet

Erythrodermic Psoriasis

  • Severe, generalized erythema affecting up to 100% of the body surface area (BSA) with various degrees of scaling
  • Skin’s protective functions are lost and patient is susceptible to infection, uncontrollable body temperature, loss of fluids and nutrients
  • Often associated with systemic symptoms (eg fever and malaise); can be life-threatening

Inverse Psoriasis

  • Lesions consist of erythematous plaques with minimal scales
  • Located in the skin folds (eg axillary, genital, perineal, intergluteal, inframammary areas)
Editor's Recommendations
Most Read Articles
01 Dec 2020
Tetanus toxoid 5 Lf, diphtheria toxoid 2 Lf, pertussis toxoid 2.5 mcg, filamentous haemagglutinin 5 mcg, fimbriae types 2 and 3 5 mcg, pertactin 3 mcg
Dr. Hsu Li Yang, Dr. Tan Thuan Tong, Dr. Andrea Kwa, 08 Jan 2021
Antimicrobial resistance has become increasingly dire as the rapid emergence of drug resistance, especially gram-negative pathogens, has outpaced the development of new antibiotics. At a recent virtual symposium, Dr Hsu Li Yang, Vice Dean (Global Health) and Programme Leader (Infectious Diseases), NUS Saw Swee Hock School of Public Health, presented epidemiological data on multidrug-resistant (MDR) gram-negative bacteria (GNB) in Asia, while Dr Tan Thuan Tong, Head and Senior Consultant, Department of Infectious Diseases, Singapore General Hospital (SGH), focused on the role of ceftazidime-avibactam in MDR GNB infections. Dr Andrea Kwa, Assistant Director of Research, Department of Pharmacy, SGH, joined the panel in an interactive fireside chat, to discuss challenges, practical considerations, and solutions in MDR gram-negative infections. This Pfizer-sponsored symposium was chaired by Dr Ng Shin Yi, Head and Senior Consultant of Surgical Intensive Care, SGH.
Jairia Dela Cruz, 5 days ago
Spending too much time sitting cannot be good for the body, and rising to one's feet breaks up such a behaviour and yields small, but meaningful, reductions in certain cardiovascular disease (CVD) risk factors, according to the results of a meta-analysis.
5 days ago
Use of thyroid hormone therapy does not seem to protect older adults with subclinical hypothyroidism against mortality, but it appears to confer survival benefits to those aged <65 years, results of a study have shown.