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Psoriasis
Edwin A. Farnell IV, MD
Michael O. Needham, MD, CPT, MC, USA
image BASICS
DESCRIPTION
  • A chronic, multisystem inflammatory disorder most commonly characterized by cutaneous erythematous papules and plaques with silvery scale. A complex genetic and immune-mediated disorder with flares related to systemic, psychological, infectious, and environmental factors. Skin disease with multiple different phenotypic variations and degrees of severity.
  • Clinical phenotypes
    • Plaque (vulgaris): most common variant (>80% of cases); well-demarcated, scaly, pink-to-red plaques of various sizes; symmetrically distributed on scalp, extensor surfaces of extremities, and trunk
    • Guttate: <2% of psoriasis patients, usually in patients <30 years of age; presents abruptly with 1- to 10-mm droplet-shaped pink papules and fine scale over trunk and extremities; often preceded by group A &bgr;-hemolytic streptococcal infection 2 to 3 weeks earlier.
    • Inverse: Affects intertriginous areas and flexural surfaces; pink-to-red plaques with minimal scale; absence of satellite pustules distinguishes it from candidiasis although may coexist.
    • Erythrodermic: ˜1-2.25% of psoriasis patients; generalized erythema and scaling, affecting >75% of BSA; associated with desquamation, hair loss, nail dystrophy, and systemic symptoms such as fever, chills, malaise, or high-output cardiac failure; may require hospital admission for management of dehydration, electrolyte abnormalities, and high risk of infection
    • Pustular: sterile pustules; several forms including generalized pustular psoriasis, annular pustular psoriasis, and impetigo herpetiformis; generalized type can result in life-threatening bacterial superinfections, sepsis, and dehydration if left untreated
    • Nail disease: pitting, oil spots, and thickening; nails involved in up to 50% of patients with psoriasis with lifetime incidence of 80-90%
    • Psoriatic arthritis: seronegative inflammatory spondyloarthropathy; mono and assymetrical oligoarthritis
EPIDEMIOLOGY
Incidence
Predominant sex: male = female. Predominant age: two peaks in incidence between the ages of 20 to 30 years and 50 to 60 years.
Prevalence
  • 2-4.7%—similar prevalence in all races
  • ˜80% of patients have mild to moderate disease (1).
ETIOLOGY AND PATHOPHYSIOLOGY
Antigenic triggers activate dendritic cells and T cells; dendritic cells produce type I interferon, and interleukin (IL)-20, which speeds keratinocyte proliferation; myeloid dendritic cells release IL-23 in lymph nodes, recruiting TH1 and TH17 cells to the lesions; T cells produce numerous cytokines, including interferon-&ggr;, IL-17, and IL-22 that stimulate keratinocytes to proliferate and produce proinflammatory antimicrobial peptides and cytokines, which recruit neutrophils to the epidermis and activate dermal fibroblasts.
Genetics
  • Genetic predisposition (probably polygenic)
  • 40% have psoriasis in a first-degree relative
  • Increased incidence of specific human leukocyte antigens (e.g., HLA-Cw6)
  • Multiple susceptibility loci contain genes involved in immune system regulation (e.g., psoriasis-susceptibility [PSORS1] locus on chromosome 6p21; polymorphisms in the IL-12/IL-13 receptor, the p40 subunit of IL-12 and IL-23, and the p19 subunit of IL-12) (2)
RISK FACTORS
  • Family history
  • Local trauma; local irritation (exacerbation)
  • HIV; streptococcal infection
  • Mental stress (exacerbation)
  • Medications (lithium, antimalarials, &bgr;-blockers, interferon, withdrawal of steroids)
  • Smoking
GENERAL PREVENTION
Avoid triggers, including trauma, sunburns, smoking, and exposure to certain medications (as mentioned earlier), alcohol, and stress; weight loss if obese.
COMMONLY ASSOCIATED CONDITIONS
  • Psoriatic arthritis
  • Obesity, metabolic syndrome, diabetes, CKD
  • Cardiovascular disease; atherosclerotic disease
  • Nonalcoholic fatty liver disease (NAFLD)
  • Autoimmune: alopecia areata, celiac disease, Crohn disease, systemic sclerosis
  • Psychiatric/psychologic: depression, suicide, emotional burden/anxiety, alcohol abuse (3)
  • Malignancy: lymphoma, nonmelanoma skin cancer with psoralen-UVA (PUVA) therapy
image DIAGNOSIS
PHYSICAL EXAM
  • Well-demarcated salmon pink-to-red erythematous papules and plaques; silvery scale
  • Distribution favors scalp, auricular conchal bowls, and postauricular area; extensor surface of extremities, especially knees and elbows; umbilicus, lower back, intergluteal cleft, and nails
  • Nail findings: pitting, oil spots, onycholysis, splinter hemorrhages, subungual hyperkeratosis
  • Auspitz sign: underlying pinpoints of bleeding following scraping of plaques
  • Koebner phenomenon: new psoriatic lesions arising at sites of skin injury/trauma
  • Genitals affected up to 40% of patients (4)
  • Sebopsoriasis: Psoriasis can overlap with seborrheic dermatitis as greasy scales on the eyebrows, nasolabial folds, and postauricular and presternal areas.
DIFFERENTIAL DIAGNOSIS
  • Plaque: seborrheic dermatitis, nummular eczema, atopic dermatitis, contact dermatitis, lichen planus, lichen simplex chronicus, tinea, pityriasis rubra pilaris, subacute/discoid lupus erythematosus, squamous cell carcinoma in situ
  • Guttate: pityriasis rosea, pityriasis lichenoides chronica, lichen planus, secondary syphilis, small plaque parapsoriasis
  • Pustular: subcorneal pustulosis, acute generalized exanthematous pustulosis, folliculitis, pemphigus foliaceous
  • Erythrodermic: cutaneous T-cell lymphoma, drug-induced erythroderma, ichthyosiform erythroderma
DIAGNOSTIC TESTS & INTERPRETATION
Initial Tests (lab, imaging)
Clinical diagnosis based on history and physical exam. May include negative rheumatoid factor, normal erythrocyte sedimentation rate (ESR), and C-reactive protein (elevated in pustular/erythrodermic variants); uric acid level may be elevated in pustular psoriasis; sterile fluid from pustules with neutrophilic infiltrate; fungal studies in hand and foot psoriasis
Diagnostic Procedures/Other
  • Psoriasis Area and Severity Index (PASI) evaluates overall severity and body surface area (BSA) involvement.
  • Physicians Global Assessment: Target plaque score and the percentage BSA together; 4-mm punch biopsy from affected skin, if necessary
  • Dermatology Life Quality Index (DLQI)
Test Interpretation
Biopsy: thickening of the stratum corneum (hyperkeratosis) with retention of nuclei (parakeratosis); elongation, thickening, and clubbing of rete ridges; dilated tortuous capillary loops in the dermal papillae; perivascular lymphocytic infiltrate, Munro microabscesses: neutrophils in stratum corneum
image TREATMENT
GENERAL MEASURES
Adequate topical hydration (emollients), sun exposure (avoid sunburns), stress relief
MEDICATION
First Line
  • Mild-to-moderate disease
    • Emollients BID: petrolatum/ointments to maintain skin hydration and minimize pruritus and risk of koebnerization
    • Topical corticosteroids
      • Anti-inflammatory, antiproliferative, immunosuppressive, and vasoconstrictive effects; tachyphylaxis develops over time, may alternate to prevent
      • Local side effects: skin atrophy, hypopigmentation, striae, acne, folliculitis, and purpura. Systemic side effects: Risk is higher, with higher potency formulations used over a large surface for a prolonged period; pregnancy Category C
      • Applications are typically twice daily until lesions flatten/resolve, then taper to PRN use for maintenance.
      • Scalp: strong potency in solution/foam vehicle; shampoos and sprays also available
      • Face, intertriginous areas, infants: low-potency corticosteroids: 1% hydrocortisone
      • Adult initial therapy: medium-potency corticosteroids daily (e.g., 0.1% mometasone or triamcinolone); strong-potency corticosteroids: 0.05% betamethasone or fluocinonide daily; superpotency corticosteroids: clobetasol, halobetasol; limit use to 2 to 4 weeks; avoid occlusive dressings; reserved for recalcitrant plaques
    • P.877

    • Vitamin D analogues: calcipotriene 0.005% ointment daily to BID; limits keratinocyte hyperproliferation; may be highly effective for short-term control in combination with a superpotent corticosteroid; should not be used with products that can alter pH, such as topical lactic acid; local side effects: burning, pruritus, edema, peeling, dryness, and erythema; pregnancy Category C
    • Topical retinoids: tazarotene 0.05% or 0.1% (Tazorac) daily; normalizes abnormal keratinocyte differentiation and diminishes hyperproliferation; may be combined with corticosteroids; side effects: local irritation, photosensitivity; pregnancy Category X
    • Topical calcineurin inhibitors: Tacrolimus 0.1% or pimecrolimus 1% may be used as steroid-sparing agents, especially in facial and intertriginous areas.
    • Comparison of topical therapies: vitamin D analogues have slower onset of action than topical corticosteroids, but longer disease-free periods for body plaques. For scalp, potent and superpotency steroids more effective (5)[A]
    • Combination of superpotent steroids and vitamin D analogs has better efficacy than either as monotherapy or come in combination compounds (6)[A].
  • Severe disease: may need combination therapy
    • Light therapy: Locally immunosuppressive and antiproliferative. Natural sunlight; UVB (broad/narrow band [BB, NB]) or PUVA: Treatment protocols are skin type dependent: PUVA most effective, followed by NB-UVB, then BB-UVB (7)[A]; well tolerated, but increased risk of nonmelanoma skin cancers with >350 treatments
    • Systemic therapies
      • Methotrexate: blocks DNA synthesis and inhibits proliferation of lymphoid tissue; start 7.5 to 15 mg/week IV, PO, IM, or SC, then increase 2.5 mg every 2 to 3 weeks, up to 25 mg; contraindicated in pregnancy; supplement with folic acid 1 to 5 mg/day to protect against side effects: hepatotoxicity, pulmonary toxicity, bone marrow suppression; baseline chest x-ray, monitor LFTs, renal function, CBC, testing for latent tuberculosis (TB); consider liver biopsy when cumulative dose reaches 3.5 to 4 g; avoid alcohol and medications that interfere with folic acid metabolism, including Bactrim, sulfamethoxazole, or hepatotoxic agents (e.g., retinoids)
      • Cyclosporine: inhibits T-cell activation; start 2.5 mg/kg/day; if insufficient response after 4 weeks, increase by 0.5 mg/kg/day; additional dosage increases every 2 weeks (max dose: 4 mg/kg/day pregnancy Category C; side effects: renal toxicity and hypertension, limit long-term use: monitor renal function, CBC with Mg2+ and K+, and BP
      • Acitretin (Soriatane): systemic retinoid; onset ranges from 3 to 6 months; start 25 to 50 mg/day given with the main meal; effective for pustular psoriasis and as a maintenance therapy after stabilization with other agents; sometimes combined with UV-B/PUVA; pregnancy Category X: Pregnancy test before starting; two forms of contraception 1 month before, during, and for at least 3 years after treatment; avoid alcohol (may convert acitretin to etretinate); side effects: alopecia, xerosis, cheilitis, hepatotoxicity, hyperlipidemia, cataracts; monitor LFTs, renal function, lipid profile, CBC, regular eye exams
    • Biologics: general guidelines: Screen for latent TB at baseline and yearly, hepatitis panel at baseline, avoid live vaccines; monitor CBC with differential, signs/symptoms of infections, heart failure, malignancy, drug-induced lupus, inflammatory bowel disease, demyelinating disorder. Some concern for “biologic fatigue” phenomenon, or loss of PASI 75 over time though each has been shown to be effective at 24 weeks with a NNT <2. All should be considered effective first-line treatments (7,8)[A]; pregnancy Category B.
      • TNF-&agr; inhibitors: etanercept (Enbrel): begin at 50 mg SC twice a week for 3 months then maintenance of 50 mg/week. Adalimumab (Humira): dosing starts at 80 mg SC for 1 week, then 40 mg SC every other week. Infliximab (Remicade): TNF inhibitor: 5 mg/kg IV at weeks 0, 2, and 6; maintenance doses of 5 mg/kg every 8 weeks thereafter; adjust interval, as needed; anaphylaxis-like infusion reaction occurs in <1% of patients.
      • IL-12/IL-23 antagonist: ustekinumab (Stelara): patients <100 kg: 45 mg SC at weeks 0 and 4, then every 12 weeks; >100 kg: 90 mg can be given.
Second Line
Immunosuppressives: azathioprine, hydroxyurea, 6-thioguanine, fumaric acid esters, and topicals: salicylic acid; anthralin
ISSUES FOR REFERRAL
Psoriasis >20% of BSA, severe extremity involvement, particularly hands and feet
SURGERY/OTHER PROCEDURES
Psoriasis and psoriatic medications can affect wound healing postoperatively; methotrexate: Monitor for postoperative infections; hold cyclosporine for 1 week before and after; some surgeons may prefer to hold therapy with biologics for up to 1 month before and after surgery.
INPATIENT CONSIDERATIONS
Admission Criteria/Initial Stabilization
Generalized pustular psoriasis/erythrodermic psoriasis: Rule out sepsis; restoration of barrier function of skin with cleaning and bandaging; intensive topical corticosteroid therapy, phototherapy, systemic therapy, particularly medications with a quick onset such as oral cyclosporine; management of electrolytes
image ONGOING CARE
FOLLOW-UP RECOMMENDATIONS
Measure BSA involvement to determine if therapy is working; change therapy or add agent if no improvement is seen.
DIET
Well-balanced diet and exercise to limit cardiovascular risk factors and decrease risk of associated conditions, including obesity, metabolic syndrome, diabetes, and atherosclerosis.
PATIENT EDUCATION
National Psoriasis Foundation: www.psoriasis.org; 800-723-9166
PROGNOSIS
Guttate form may be self-limited and remit after 4 months; chronic plaque type is lifelong, with intermittent spontaneous remissions and exacerbations; erythrodermic and generalized pustular forms may be severe and persistent.
REFERENCES
1. Menter A, Korman NJ, Elmets CA, et al. Guidelines of care for the management of psoriasis and psoriatic arthritis: section 6. Guidelines of care for the treatment of psoriasis and psoriatic arthritis: case-based presentations and evidence-based conclusions. J Am Acad Dermatol. 2011;65(1):137-174.
2. Villaseñor-Park J, Wheeler D, Grandinetti L. Psoriasis: evolving treatment for a complex disease. Cleve Clin J Med. 2012;79(6):413-423.
3. Brenaut E, Horreau C, Pouplard C, et al. Alcohol consumption and psoriasis: a systemic literature review. J Eur Acad Dermatol Venereol. 2013;27(Suppl 3):30-35.
4. Meeuwis KA, de Hullu JA, Massuger LF, et al. Genital psoriasis: a systemic literature review on this hidden skin disease. Acta Derm Venereol. 2011;91(1):5-11.
5. Mason AR, Mason J, Cork M, et al. Topical treatments for chronic plaque psoriasis. Cochrane Database Syst Rev. 2013;(3):CD005028.
6. Hendricks AG, Keijsers RR, de Jong EM, et al. Efficacy and safety of combinations of first-line topical treatments in chronic plaque psoriasis: a systematic literature review. J Eur Acad Dermatol Venereol. 2013;27(8):931-951.
7. Almutawa F, Alnomair N, Wang Y, et al. Systematic review of UV-based therapies for psoriasis. Am J Clin Dermatol. 2013;14(2):87-109.
8. Nast A, Jacobs A, Rosumeck S, et al. Efficacy and safety of systemic long-term treatments for moderate-to-severe psoriasis: a systematic review and meta-analysis [published online ahead of print June 5, 2015]. J Invest Dermatol. 2015;135(11):2641-2648.
Additional Reading
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Galván-Banqueri M, Marín Gil R, Santos Ramos B, et al. Biologic treatments for moderate-to-severe psoriasis: indirect comparison. J Clin Pharm Ther. 2013;38(2):121-130.
See Also
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Arthritis, Psoriatic
Codes
&NA;
ICD10
  • L40.9 Psoriasis, unspecified
  • L40.50 Arthropathic psoriasis, unspecified
  • L42 Pityriasis rosea
Clinical Pearls
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Chronic lifelong inflammatory skin condition with remissions and exacerbations; set realistic expectations with patient. Disease burden not limited to skin. If one medication does not work, use/combine with another agent.