Incidence

1. Disease occurs in 1% to 3% of the world population.
2. Psoriasis affects 7.5 million people in the United States, with 80% of them having plaque psoriasis.
3. It occurs at any age:
   1. Peaks of onset seen in adolescence.
   2. Young adult (16–22 years old).
   3. Adult (50–60 years old).

Pathogenesis

1. Etiology is unknown; this is a multifactorial disease with a definite genetic component. Hyperproliferation of the epidermis and inflammation of the epidermis and dermis are seen, with epidermal transit time rapidly increased (six- to nine-fold). A T-lymphocyte-mediated dermal immune response may be due to a microbial antigen or autoimmune process.

Predisposing Factors

1. Family history.
2. Drugs that exacerbate condition:
   1. Lithium.
   2. Beta blockers.
   3. Nonsteroidal anti-inflammatory drugs (NSAIDs).
   4. Antimalarials.
   5. Sudden withdrawal of systemic or potent topical corticosteroids.
3. Stress (common triggering factor).
4. Local trauma or irritation.
5. Recent streptococcal infection.
6. Alcohol use.
7. Tobacco use.
8. HIV association; suspected if onset is abrupt.
9. Obesity.
10. Vitamin D deficiency.

Common Complaints

1. Dry scaly rash.

Other Signs and Symptoms

1. Pruritic and/or painful lesions
2. Silvery scales on discrete erythematous plaques:
   1. Onset commonly occurs as a guttate form with small, scattered, teardrop-shaped papules and plaques after a streptococcal infection in a young adult.
   2. Larger, chronic plaques occur later in life.
3. Lesions are commonly seen on scalp, elbows, and knees but may involve any area of the body.
4. Glossitis or geographic tongue: Small pits or yellow-brown spots (oil spots).
5. Positive Auspitz sign: Punctate bleeding points with removal of scale.
6. Onycholysis.
7. Stippled nails and pitting; approximately 50% of patients have nail involvement.
8. Periarticular swelling of small joints of fingers and toes. Joint pain and involvement signals psoriatic arthritis.
9. Pustular variant with predominant involvement of hands and/or feet, including nails.

Subjective Data

1. Question the patient regarding any predisposing factors listed earlier to identify risk factors.
2. Ask the patient if there have been changes in the course of symptoms.
3. Ascertain whether the symptoms worsen in winter and clear in summer.
4. Determine site of lesion and whether the onset is sudden or painful.
5. Ask the patient to describe the skin: Is it itchy or painful?
6. Assess lesions for any associated discharge (blood or pus).
7. Ask if the patient is using any new soaps, creams, or lotions.
8. Rule out any exposure to industrial or domestic toxins.
9. Ask the patient about any possible contact with venereal disease (sexually transmitted infections [STIs]).
10. Review whether there was close physical contact with others with skin disorders.
11. Elicit information regarding any preceding systemic symptoms (fever, sore throat, and anorexia).

Physical Examination

1. Check temperature (if indicated).
2. Inspect:
   1. Inspect skin; note type of lesion and distribution. Assess oral mucosa, nails, and nail beds.
   2. Assess joints for erythema and/or synovitis (inflammation of the synovial membrane).
3. Palpate: Palpate joints for tenderness and synovitis.

Diagnostic Tests

1. None is indicated unless HIV infection is suspected; order HIV test.
2. If joint inflammation is present, consider rheumatoid factor, erythrocyte sedimentation rate, C-reactive protein, and uric acid.
3. If there is a history of streptococcal infection, order antistreptolysin O titer.

Differential Diagnoses

1. Psoriasis.
2. Scalp: Seborrheic dermatitis.
3. Body folds: Candidiasis.
4. Trunk: Pityriasis rosea, tinea corporis.
5. Hand dermatitis.
6. Squamous cell carcinoma (SCC).
7. Cutaneous lupus erythematosus.
8. Eczema.

Plan

1. General interventions:
   1. This is a chronic disorder that requires long-term treatment, a high degree of patient involvement, and therapy that is simple and inexpensive.
   2. Aim of treatment is control, not cure.
   3. Exposure to sunlight may be beneficial. However, a small percentage of patients worsen with exposure to sunlight.
   4. Sequence of agents for involvement of less than 20% body surface is as follows:
      1. Emollients (Eucerin cream or Aquaphor cream).
      2. Keratolytic agents (salicylic acid gel or ointment).
      3. Topical corticosteroids: Use lowest potency to control disease.
      4. Calcipotriene ointment: Vitamin D analogue (calcipotriene ointment 0.005%).
      5. Anthralin: Use as short-contact therapy 1% to 3%.
      6. Coal tar (Estar, Psorigel): Use in conjunction with topical steroids or anthralin. May apply at bedtime or in the morning for 15 minutes and then shower off.
      7. Medicated shampoos: Useful for scalp psoriasis, in conjunction with topical steroids and other treatments
2. See Section III: Patient Teaching Guide “Psoriasis.”
   1. Help the patient understand the chronic nature of this disease characterized by flares and remission. Teach stress monitoring and control. Assist with coping techniques.
   2. A trial of a gluten-free diet may be tried to help symptoms. See Appendix B for Gluten-Free Diet.
3. Pharmaceutical therapy: If disease is not controlled with first agent, then an alternative agent may be tried:
   1. Mild to moderate disease: Topical steroids as first-line therapy.
   2. Emollients to start treatment (e.g., Eucerin Plus lotion or cream, Lubriderm Moisture Plus, Moisture).
   3. Scalp: Use coal tar shampoo (Zetar, T/Gel, Pentrax) in place of regular shampoo two times per week:
      1. Apply lather to scalp, allow to soak for 5 minutes, and then rinse.
      2. If scale is very thick, use P and S Liquid (over-the-counter [OTC]). Massage in at night and wash out in morning.
   4. For additional treatment as needed, apply triamcinolone acetonide 0.1% (Kenalog 0.1%) lotion or equivalent to scaly, stubborn areas once or twice daily until controlled. Avoid face.
   5. Dovonex scalp solution: Apply on dry scalp as directed.
   6. Face and skin folds: Apply hydrocortisone cream 1% sparingly up to 4 weeks, preferably no more than 2 weeks. If lesions are unresponsive, consider increasing to 2.5% and taper quickly with improvement.
   7. Body, arms, and legs: Use triamcinolone acetonide 0.025% (Aristocort A) cream twice daily up to 2 weeks. Avoid normal skin.
   8. For thick plaques, try Keralyt gel (6% salicylic acid), then corticosteroids.
   9. Coal tar (Estar gel) once or twice daily in combination with corticosteroids.
   10. Anthralin (Dritho-Creme) is beneficial as an alternate to steroid lotion for scalp psoriasis. Avoid sunlight.
   11. Vitamin D₃ analogue (Calcipotriol), twice daily up to 8 weeks, is comparable to midpotency corticosteroids. Avoid face and skin folds.

Follow-Up

1. See patients in 2 to 3 weeks to evaluate treatment.
2. Follow up in 2 months to monitor side effects.
3. Follow-up must be individualized for each patient.

Consultation/Referral

1. Medical management: For involvement greater than 20% of body, refer the patient to a dermatologist for the following:
   1. Light therapy with UVA or UVB. UVB light therapy is often used in conjunction with keratolytic agents.
   2. Synthetic retinoids: Etretinate or acitretin.
   3. Low-dose cyclosporine or Azulfidine.
2. Refer patients with extensive disease, psoriatic arthritis, or inflammatory disease to a rheumatologist. Medications are used to suppress the immune system’s response, and include adalimumab (Humira), alefacept (Amevive), etanercept (Enbrel), infliximab (Remicade), and ustekinumab (Stelara).
3. Cases of generalized pustular psoriasis of exfoliative erythroderma should be referred immediately to a dermatologist.
4. All systemic therapies should be given under supervision of a dermatologist or rheumatologist.

Individual Considerations

1. Geriatrics:
   1. First-line therapy for mild to moderate psoriasis in the elderly population is topical treatments. Systemic steroid therapies place geriatrics at a higher risk for adverse effects including atrophy, rebound phenomenon, tachyphylaxis, secondary skin infections, telangiectasia, and purpura.
   2. If topical treatment is not effective, before considering other treatments, do an assessment for patient adherence and physical function abilities. Verify the patient is using the medication correctly and consistently.
2. If the medication is being implemented appropriately, then consider second-line treatments of systemic medications or UVB phototherapy. Second-line therapies must have a thorough review of comorbidities, any patient needs for assistance, and an evaluation of functional status before initiating the systemic/phototherapy.