Plaque Psoriasis Clinical Presentation

Updated: Mar 17, 2021
  • Author: Harvey Lui, MD, FRCPC; Chief Editor: Dirk M Elston, MD  more...
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Presentation

History

The typical history given by a patient with plaque psoriasis is relatively straightforward: patients report prominent itchy, red areas with increased skin scaling and peeling. Patients are particularly aware of lesions on the scalp and extensor surfaces. Patients typically are self-conscious about their lesions and commonly report using clothing to cover affected sites and avoiding potentially embarrassing social activities.

Patients commonly recognize that new lesions appear at sites of injury or trauma to the skin. This isomorphic phenomenon (Koebner reaction) typically occurs 7-14 days after the skin has been injured and has been found in 38-76% of patients with plaque psoriasis. In some patients, so-called reverse-Koebner reactions have also been noted in which preexisting psoriatic plaques actually clear after injury or trauma to the skin.

Patients may report that their disease worsens in the winter and improves in the summer.

Significant joint pain, stiffness, and deformity are reported in the 10-20% of patients with psoriasis who develop psoriatic arthritis.

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Physical Examination

Several cardinal features of plaque psoriasis can be readily observed during the physical examination.

Plaques

Psoriasis manifests as elevated lesions that vary in size from one to several centimeters (see image below). The thickened epidermis, expanded dermal vascular compartment, and infiltrate of neutrophils and lymphocytes account for the psoriatic lesions being raised and easily palpable. The number of lesions may range from few to many at any given time.

Plaque psoriasis. Courtesy of University of Britis Plaque psoriasis. Courtesy of University of British Columbia, Department of Dermatology and Skin Science.

The plaques are irregular to oval and are most often located on the scalp, trunk, and limbs, with a predilection for extensor surfaces such as the elbows and knees. Smaller plaques may coalesce into larger lesions, especially on the legs and sacral regions (see image below). Fissuring within plaques can occur when lesions are present over joint lines or on the palms and soles.

Plaque psoriasis. Courtesy of University of Britis Plaque psoriasis. Courtesy of University of British Columbia, Department of Dermatology and Skin Science.

Well-circumscribed margins

Psoriatic plaques are well defined and have sharply demarcated boundaries. Psoriatic plaques occasionally appear to be immediately encircled by a paler peripheral zone referred to as the halo or ring of Woronoff.

Red color

The color of psoriatic lesions is a very distinctive rich, full, red color. Lesions on the legs sometimes carry a blue or violaceous tint.

Scale

Psoriatic plaques typically have a dry, thin, silvery-white or micaceous scale; however, the amount and thickness of this scale is quite variable. Removing the scale reveals a smooth, red, glossy membrane with tiny punctate bleeding points. These points represent bleeding from enlarged dermal capillaries after removal of the overlying suprapapillary epithelium. This phenomenon is known as the Auspitz sign.

Symmetry

Psoriatic plaques tend to be symmetrically distributed over the body. Lesions typically have a high degree of uniformity with few morphologic differences between the two sides.

Pruritus

Pruritus, one of the main symptoms of plaque psoriasis, is quite variable in intensity but should not be ignored. Emotional instability (eg, high levels of anxiety, depression) that might be induced by the disease often manifests as an increased tendency to scratch.

Nail psoriasis

Nail changes are commonly observed in patients with plaque psoriasis. Nails may exhibit pitting, onycholysis, subungual hyperkeratosis, or the oil-drop sign. A proper assessment of any patient suspected of having psoriasis should include careful examination of the nails.

Psoriasis in children

Plaque psoriasis manifests slightly differently in children. Plaques are not as thick, and the lesions are less scaly. Psoriasis may often appear in the diaper region in infancy and in flexural areas in children. The disease more commonly affects the face in children compared with adults.

Inverse psoriasis

This is a variant of psoriasis that spares the typical extensor surfaces and affects intertriginous (ie, axillae, inguinal folds, inframammary creases) areas with minimal scale.

Psoriatic arthritis

Approximately 10-20% of all cases of plaque psoriasis are associated with psoriatic arthritis. Signs of psoriatic arthritis include the following:

  • Red, warm, tender, and inflamed joints

  • Joint deformity

  • Dactylitis

  • Sausage digits

Obesity

Patients with obesity and psoriasis may have an increased risk of cardiovascular disease. This association appears to be strongest in younger patients with severe disease and may be related to the metabolic syndrome. [13]

Alcoholism

Alcoholism can be considered a complication of psoriasis. Male patients with severe disease are particularly at risk for this type of substance abuse.

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