Plaque Psoriasis

Table of Contents

Table of Contents

Published July 2021
Mollie Oudenhoven, MD1
Molly Weinberg, MD2
Mariam Alam, MD3
Expert Review – Gil Weintraub, MD4
1 Clinical instructor, Department of Pediatrics and Chief Resident in Dermatology, University of Colorado. 2 Clinical Instructor, Department of Medicine, University of Colorado. 3 Clinical Instructor, Department of Medicine and Resident in Dermatology, University of Washington. 4 Assistant Professor, Department of Dermatology, University of Colorado


  1. Identify psoriasis based on characteristic morphology and distribution.
  2. List the main comorbidities associated with psoriasis.
  3. Describe the association between guttate psoriasis and streptococcal infections.

Teaching Instructions

Plan to spend 5-10 minutes practicing the flow of the presentation and reviewing the images of squamous cell carcinoma provided.

Present the images by expanding the window below or downloading the PowerPoint file (preferred). Ask the learners to provide a description of the lesions they are viewing. Advance using the arrows or scroll wheel on the mouse to reveal subsequent questions with answers and graphics.

Dermatology description: Well-demarcated erythematous pink plaques with silvery scale on the trunk and extensor surfaces.

Diagnosis: Plaque psoriasis

Teaching: Psoriasis is a common, chronic inflammatory disease of the skin characterized by sharply demarcated erythematous plaques with silvery scale. Psoriasis classically involves the scalp and extensor surfaces (ie elbows, knees), but can include any site, including the nails. Lesions can be mildly pruritic and resolve with dyspigmentation, but not scarring. 

Psoriatic arthritis is the major associated systemic manifestation, typically presenting with asymmetric oligoarthritis. Other comorbidities include cardiovascular disease, metabolic syndrome, and depression, especially in those with moderate to severe disease. 

Psoriasis occurs secondary to a genetic predisposition triggered by environmental factors. Importantly, guttate psoriasis, characterized by small discrete rain-drop sized papules with scale, can occur secondary to streptococcal pharyngitis. For patients with this presentation, antibodies to streptolysin O, anti-DNAse B, or streptozyme can confirm previous infection. If acutely symptomatic, a rapid strep test and throat culture can be obtained. If positive, treatment for streptococcal pharyngitis is recommended to help prevent recurrence. 

Question 2: What are the most common comorbidities associated with psoriasis?
  Psoriatic arthritis>>cardiovascular disease, metabolic syndrome, depression.
  Pro tip: Nail changes is a strong predictor for development of psoriatic arthritis. 

Question 3: For this variant of psoriasis, what would you test for?
  Streptococcal pharyngitis.

Presentation Board

Take Home Points

  1. Psoriasis has well-demarcated plaques with silvery scale, classically on extensor surfaces.
  2. The most common systemic manifestation of psoriasis is psoriatic arthritis. Patients also have an increased relative risk of cardiovascular disease, metabolic syndrome, and depression. 
  3. Guttate psoriasis can be triggered by streptococcal pharyngitis.


Van de Kerkhof, CM. Psoriasis. In: Bolognia L eds. Dermatology.  4th edition. Elsevier; 2018: 138-158. 

Brandon Fainstad


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