What is psoriasis?Autoimmune chronic inflammatory diseases of the skin. | Occurs due to overstimulation of immune cells that causes excessive proliferation of keratinocytes. | Silvery scaling of skin and itching. | Not contagious and not severe in many cases (outpatient mx) |
General featuresErythematous papules and silvery-white scaling plaques | Well demarcated, raised, red patches | Usually not itchy (pruritus is typically mild - 80% of cases) | Affects scalp, back, elbows and knees (extensor surfaces), and nails (thimble pitting). |
Erythematous- superficial redness caused by dilation of capillaries.
Nail pitting - small, round depression in the nail. Clinical variants.Plaque psoriasis | Well demarcated individual thick, scaly, erythematous lesions | Guttate psoriasis | numerous small, scaly, red or pink, tear-drop shaped lesions | Psoriatic nail disease | Drug-induces psoriasis | Psoriatic arthritis | Inflammation of joints on hand, feet and spine that can occur with psoriasis | Pustular psoriasis | appears as red bumps filled with noninfectious pus (pustules) | Flexural/inverse psoriasis | occurs in skin folds and flexor surfaces creases of joints | Erythodermic psoriasis | generalized erythematous lesions. | Scalp psoriasis | affects the scalp |
Plaque PsoriasisMost common type | Thick, scaly, erythematous lesions | Lesions are red with silver-white scaling | Common sites: | Extensor surfaces of elbows and knees. | | | Lower back | | | Scalp (can cause temporary hair loss) | | | Palms | | | Nails- pitting and onycholysis |
Onycholysis - separation of the nail from the nail bed Guttate PsoriasisOften preceded by Streptococcal infection (Streptococcus pharyngitis) | Resolves quickly |
| | Erythrodermic PsoriasisThere is increase in cutaneous blood flow, heat loss, and water loss | Skin becomes red. | Scaling is absent (although this can proceed the erythroderma). |
Inverse/Flexural PsoriasisCommon sites: | Genitals (between thigh and groin) | | | Armpits | | | Under an overweight abdomen (panniculus) | | | Under the breasts (inflammatory fold) | Increased by friction and sweat | Vulnerable to fungal infections | Looks like smooth inflamed patches on skin |
Psoriatic arthritisJoint and Connective tissue inflammation. | Most common joints affected: | Fingers and toes | Results in Dacylitis | Other joints: | Knees, hips, spine (spondylitis) | Morning stiffness of affected joints |
Dacylitis - Sausage shaped swelling of fingers and toes. Pustular psoriasisCan be localized, common to hands and feet | Palmoplantar pustulosis | Or generalized, widespread patches |
EtiologyGenetics | Precipitating factors | 1. Infections | Pharyngitis, HIV | 2. Drugs | Beta blockers, anti-malarial, lithium, NSAIDs, systemic steroid withdrawal | 3. Alcohol and smoking | 4. Emotional stress | 5. Local trauma |
GradingMild (3% of the body) | Moderate (3-10% of the body) | Severe | Degree of severity is based on: | proportion of body surface area affected | | | disease activity (plaque, redness, scaling) | | | response to previous treatments | | | impact of the disease in the patient |
DiagnosisBased on appearance of the skin | Skin biopsy, or scrapping - to rule out other disorders | Biopsy shows clubbed rete pegs if positive for psoriasis | Auspitz sign | small pinpoint bleeding when scales are scraped off |
TreatmentMild disease | Emolients | Mild-to-moderate disease | Topical corticosteroids (triamcinolone, fluocinonide, clobetasol), emollients, topical retinoids (tazarotene), vitamin D analogs (calcipotriene, calcitriol) | For facial areas | Topical tacrolimus and Pimecrolimus | Severe | Phototherapy, MTX, cyclosporine, anti-T cell agent, anti-TNF agent |
| | Vitamin D analogsAvoid use on delicate skin areas (face, flexures) because of irritation. | Combine with steroids to increase efficiency |
Coal TarAnti-inflammatory, anti-pruritic, anti-mitotic |
Systemic TherapiesFor severe generalized psoriasis intolerant after topical therapy | MTX | S/E: hepatic fibrosis, myelosuppression, teratogenic | Hydroxyurea | S/E: myelosuppression, skin reactions, liver toxicity, teratogenic | Cyclosporine | S/E: renal toxicity, HTN, gingival hypertrophy |
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