Diagnosis

Psoriasis

Etiology

Cause [syb]

• Unknown

• Genetic predisposition: Familial occurrence, HLA antigens, racial and ethnic groups

• Enviromental trigger: Trauma/Koebner phenomenon, infection, hormone, sunlight, tobacco, alcohol, emotion, drugs (chloroquine, lithium, beta-blockers, steroids, and NSAIDs), tobacco, alcohol, emotion)

Pathogenesis [syb]

1. Autoimmune disease mediated by T lymphocytes

2. Dermal infiltration of activated T cells --> stimulate the proliferation of keratinocytes

3. Dysregulation in keratinocyte turnover:

   • Epidermal hyperplasia

   • Parakeratosis

   • Cells fail to secrete lipids --> formation of thick plaques

4. These factors induce each other, leading to a vicious cycle of keratinocyte proliferation and inflammatory reaction

5. Classification:

   • Type 1 psoriasis: Positive family history, before age 40, associated with HLA-Cw6

   • Type 2 psoriasis: No family history, after age 40, not associated with HLA-Cw6

6. Typical clinical manifestation:

   • Lesions: Well-defined erythematous plaques covered with silvery scales

   • Localization: scalp, extensors of knees/elbows, and lumbosacral region

Types of psoriasis [nov]

• Chronic stationary psoriasis (psoriasis vulgaris): Most common

  scalp, extensor surfaces, genitals, umbilicus, and lumbosacral and retroauricular

• Plaque psoriasis: Extensor surfaces of the knees, elbows, scalp, and trunk

• Guttate psoriasis: Trunk; 2-3 weeks after an upper respiratory tract infection with group A beta-hemolytic streptococci

• Inverse psoriasis: flexural surfaces, armpit, and groin; under the breast; and in the skin folds (often misdiagnosed as a fungal infection)

• Pustular psoriasis: palms and soles or diffusely over the body

• Erythrodermic psoriasis: erythema of the entire body surface

• Scalp psoriasis

• Nail psoriasis: may lead to onychomycosis

• Psoriatic arthritis: usually in the hands and feet and, occasionally, the large joints

• Oral psoriasis: cheilosis

• Eruptive psoriasis: upper trunk and upper extremities

• Napkin psoriasis: diaper region

• Linear psoriasis: within a dermatome

• Ocular: Ectropion, trichiasis, conjunctivitis, conjunctival hyperemia, keratitis, blepharitis

Complications [syb]

• Secondary infections

• Poor cosmesis

• Psoriatic arthritis

• Ocular manifestations

• Risk of lymphoma

• Increased risk of adverse cardiac events

Epidemiology

Incidence per 100.000 [1be][noe][24u][py9][rfm][aie][n1y][adg][8b6][a8u]

Prevalence per 100.000 [1be][noe][24u][py9][rfm][aie][n1y][adg][8b6][a8u]

Approach

• Blood test: WBC, creatinine, liver function tests, hepatitis, tuberculosis, HIV, hCG, rheumatoid factor (negative), uric acid (elevated)

• Biopsy

• Throat swab

• Fluid from pustules

• Nail microscopy

• X-ray

• Rheumatoid factor

Treatment

1. Nondrug therapy:

   • Phototherapy: Combines psoralen with exposure to ultraviolet light

   • Stress reduction

   • Sunshine, sea bathing, moisturizers, oatmeal baths

   • Punctal occlusion (and ocular lubricants): For keratoconjunctivitis sicca

   • Bandage contact lens: To retard corneal melting

2. Pharmacotherapy

   • Topical corticosteroids: betamethasone 0.025-0.1% cream [nov]

   • Topical aryl hydrocarbon receptor (AhR) agonists

   • Ophthalmic corticosteroids

   • Intramuscular corticosteroids

   • Intralesional corticosteroids: resistant plaques and psoriatic nails

   • Coal tar 0.5-33%

   • Keratolytic agents (anthralin, urea): facilitate direct steroid contact with the skin

   • Vitamin D analogs (calcitriol ointment)

   • Topical retinoids

   • Antimetabolites (methotrexate)

   • Immunomodulators (tacrolimus topical 0.1%, cyclosporine, alefacept, ustekinumab)

   • Tumor necrosis factor (TNF) inhibitors (infliximab, etanercept, adalimumab)

   • Phosphodiesterase-4 inhibitors (apremilast, roflumilast topical)

   • Interleukin inhibitors

   • Artificial tears

Differential diagnoses

Conjunctivitis, Contact dermatitis, Cutaneous T-cell lymphoma, Eczema, Gout, Keratitis, Lichen planus, Lichen simplex chronicus, Mycosis fungoides, Onychomycosis, Pityriasis alba, Pityriasis rosea, Pseudogout, Psoriatic arthritis, Reactive arthritis, Rheumatoid arthritis, Seborrheic dermatitis, Squamous cell carcinoma, Syphilis, Tinea corporis, Tinea unguium