Skip to Main Content

For further information, see CMDT Part 6-38: Psoriasis

KEY FEATURES

Essentials of Diagnosis

  • Silvery scales on bright red, well-demarcated plaques, usually on the knees, elbows, and scalp

  • Nails: pitting and onycholysis (separation of the nail plate from the bed)

  • Mild itching is common

  • May be associated with psoriatic arthritis

  • Histopathology is helpful

General Considerations

  • A common benign, chronic inflammatory skin disease with both a genetic basis and known environmental triggers

  • Injury or irritation of normal skin tends to induce lesions of psoriasis at the site (Koebner phenomenon)

  • Obesity worsens psoriasis, and significant weight loss may lead to substantial improvement

  • Psoriasis has several variants—the most common is the plaque type

CLINICAL FINDINGS

  • There are often no symptoms, but itching may occur

  • Although psoriasis may occur anywhere, examine the scalp, elbows, knees, palms and soles, umbilicus, and nails

  • The lesions are red, sharply defined plaques covered with silvery scales; the glans penis and vulva may be affected; occasionally, only the flexures (axillae, inguinal areas including genitalia) are involved ("inverse psoriasis")

  • Fine stippling ("pitting") in the nails is highly suggestive

  • Persons with psoriasis often have a pink or red intergluteal fold

  • There may be associated seronegative arthritis, often involving the distal interphalangeal joints

  • Eruptive (guttate) psoriasis consisting of numerous, smaller lesions 3–10 mm in diameter occurs occasionally after streptococcal pharyngitis

Differential Diagnosis

  • Atopic dermatitis (eczema)

  • Contact dermatitis

  • Nummular eczema (discoid eczema, nummular dermatitis)

  • Tinea

  • Candidiasis

  • Intertrigo

  • Seborrheic dermatitis

  • Pityriasis rosea

  • Secondary syphilis

  • Pityriasis rubra pilaris

  • Onychomycosis (nail findings)

  • Cutaneous features of reactive arthritis

  • Cutaneous T-cell lymphoma (mycosis fungoides)

DIAGNOSIS

Diagnostic Procedures

  • The combination of red plaques with silvery scales on elbows and knees, with scaliness in the scalp or nail findings, is diagnostic

  • Psoriasis lesions are well demarcated and affect extensor surfaces—in contrast to atopic dermatitis, with poorly demarcated plaques in flexural distribution

  • In body folds and groin, scraping and culture for Candida and examination of scalp and nails will distinguish inverse psoriasis from intertrigo and candidiasis

TREATMENT

  • Choice of therapy depends on extent of affected body surface area (BSA) and the presence of other findings (eg. arthritis)

  • Certain medications, such as β-blockers, antimalarials, statins, lithium, and prednisone taper, may flare or worsen psoriasis

  • See Table 6–2

Table 6–2.Useful topical dermatologic therapeutic agents.1

Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.

  • Create a Free Profile