By Gary M. White, MD
Red, scaly, well-defined plaques.
Psoriasis is a benign but chronic autoimmune-mediated inflammatory and hyperproliferative skin condition. It affects about 1-2% of the population.
See also inverse, scalp, perianal, periungual, groin, nails, palms, joints, HIV positive, guttate, pediatric, diaper and pustular psoriasis.
Red, scaly, papulosquamous plaques may develop almost anywhere, but are most common on the elbows and knees, scalp, and shins. Men commonly develop lesions on the penis and this may be their presenting problem. Lesions of the body folds often appear as red plaques without scale. Itching may occur, but is not nearly as intense as with eczema. Seborrheic dermatitis may coexist. In fact, there is a spectrum in the scalp from dandruff to seborrheic dermatitis to psoriasis. Sometimes the term sebopsoriasis is used.
Some medications have been thought to potentially trigger the onset of or exacerbate preexisting psoriasis. The strongest evidence relates to beta-blockers, lithium, antimalarials and interferon. In patients without a history of psoriasis, use of beta-blockers for 6 years or longer is associated with the development of psoriasis [JAMA Derm 2014;150;957]. Lithium has more commonly been associated with psoriasis exacerbation with a mean latency period of 20 weeks. Chloroquine supposedly can exacerbate psoriasis with a latency period from 4-12 weeks.
Patients with psoriasis are at increased risk of cardiovascular events including heart attack and stroke. One study found a 1% increased risk for a future CV event per additional year of psoriasis [JAAD 2017;77;650].
Fatigue, defined as "an overwhelming, sustained sense of exhaustion and decreased capacity for physical and mental work", may be a symptom of various medical conditions including psoriasis [Cutis 2016;97;125]. Although hard to quantify and thus hard to study, it is reasonable to think that effective therapy, e.g. biologic agents, can improve symptoms of psoriasis-associated fatigue.
Sixteen of 45 (35.5%) patients with plaque psoriasis had bacterial DNA in their blood whereas none of the 27 controls did [JAMA Derm 2015;151;670]. Escherichia coli was the most common source, suggesting increased permeability of the intestinal mucosa being associated. The theory is that the presence of bacteria in the blood stream stimulates the immune system, triggering psoriasis.
The Koebner phenomenon refers to the development of skin disease (classically psoriasis) at the sites of trauma. Alternatively, the Renbök phenomenon describes somewhat the opposite, an inhibition of a particular disease by another disease or condition, e.g., alopecia areata sparing areas affected by seborrheic dermatitis.
Psoriasis is, in its most basic sense, the body's immune system invading the skin. The goal of treatment is to suppress the immune system with the least amount of side effects.
|Body Location||Common Treatments|
|Scalp||Tar shampoos, Class I steroid solution BID, or fluocinolone acetonide oil, 0.01% QHS|
|Face||Low- to medium-strength steroid, pimecrolimus or tacrolimus|
|Ears||Medium-strength steroid, cream or even liquid.|
|Axilla||Low- to medium-strength steroid, pimecrolimus or tacrolimus|
|Trunk, Extremities, Limited||Class I steroids BID for 2 weeks, then intermittent alone, or in combination with, tazarotene or calcipotriene|
|Groin||Low- to medium-strength steroid, pimecrolimus or tacrolimus|
|Palms and Soles||Class I steroid, cream or ointment BID initially, then prn|
|Nails||Topicals not too effective. Systemic agents may help.|
For limited psoriasis, e.g., less than 10% body surface area, a high-potency topical steroid may be all that is needed. Hydrocortisone and even triamcinolone will not do. For psoriasis of the body and/or extremities, a class I topical steroid (e.g., clobetasol ointment) is a good starting point. It should be applied BID for 2 weeks in an attempt to achieve clearing. If this occurs, the patient should then apply it for 2-4 consecutive days during the week with only emollients (or calcipotriene or a calcineurin inhibitor) used for the rest. This treatment regimen is an attempt to maintain clear skin but reduce the possibility of atrophy. The patient should always be warned of the potential for atrophy and/or stretch marks if potent topical steroids are used for months in the same area. These potent steroids should not be used on the face or body folds. Follow-up examination should always look for atrophy and new stretch marks.
For the scalp, a steroid liquid, foam or spray, e.g., clobetasol solution, is in order. Alternatively fluocinolone in an oil formation (Derma-Smoothe) may be applied and left in overnight and shampooed out in the AM.
Some patients may try to control widespread psoriasis with large amounts of potent topical steroids. The doctor must prevent this by monitoring the amount of steroid refilled over time. Stria, ulcers, weight gain, suppression of the hypothalamic-pituitary axis and a Cushingoid body habitus are all possible side effects.
Combining a Class I topical steroid QD with another agent, e.g., tazarotene or calcipotriene QD, can be quite helpful. Not only is it more efficacious, it also cuts the exposure to the steroid in half, and minimizes the risk for steroid atrophy. One study [JAAD 1998;39;447] showed the benefit of treating initially with a halobetasol QD and calcipotriene QD for 2 weeks, followed by halobetasol BID on the weekend and calcipotriene BID during the week.
Tazarotene (trade name Tazorac in either a 0.05% or 0.1% gel) is another topical treatment for psoriasis. It is a topical retinoid and is applied once daily. Local irritation is the main side effect and thus, tazarotene is often combined with a medium- to high-potency topical steroid (e.g., mometasone, betamethasone valerate). For example, the patient may apply the steroid QAM and the tazarotene QHS. Its use is usually limited to 20% of body surface area.
Calcipotriene (Dovonex) is a very helpful topical medication for psoriasis. It comes as a cream, ointment and solution (for the scalp) and all are applied BID. As noted above, calcipotriene is very effective if given once a day in conjunction with a potent topical steroid once a day. Occlusion significantly improves the efficacy of calcipotriol [CED 1993;18;504]. In fact, for patients with a few isolated plaques, calcipotriol covered with a hydrocolloid dressing (e.g., DuoDERM) changed once weekly can clear lesions in 3-4 weeks [Dermatology 2000;200;25].
Pimecrolimus cream and tacrolimus ointment BID are useful for psoriasis of the body folds, e.g., axilla, groin and genitals, as they will not cause atrophy of the skin, even with daily use.
Topical tar preparations are used much less frequently these days given the cosmetic elegance of the newer preparations. Still, a topical tar preparation daily can be very helpful. It may be used with benefit in conjunction with nbUVB as it increases efficacy of UVB. Some pharmacies can compound tar with a topical steroid with or without salicylic acid (e.g., LCD 10% plus salicylic acid 6% in triamcinolone or fluocinonide ointment).
Contrary to most other situations, the doctor may tell the patient to get some sun as the ultraviolet rays suppress the immune system's activity in the skin and thus can help chase away psoriasis. A gradual increase in exposure is important. Burning can flare psoriasis through the Koebner phenomenon.
Philips BlueControl is a battery-powered wearable medical device that uses light-emitting diode blue light therapy to treat mild-to-moderate psoriasis. In a trial of patients with mild-to-moderate psoriasis vulgaris treated for 12 weeks, an average PASI reduction of 50% was obtained with no side effects.
The pulsed dye laser is FDA-approved for the treatment of psoriasis. It is recommended for localized, treatment-resistant disease. It is not recommended for widespread or inflammatory disease, or for patients who Koebnerize.
If the above measures fail, see systemic treatment.
See perianal, periungual, groin, nails, joints, inverse, scalp, and palms and soles.
Mild- to moderate-potency topical steroids may be used. Light therapy is safe during pregnancy.
Patients homozygous for HLA-Cw*0602 carriage and prone to streptococcal-induced psoriasis exacerbation may benefit from tonsillectomy [JAAD 2016;75;889].
See HIV positive, guttate, pediatric, diaper, ostraceous and pustular psoriasis.
See also Psoriasis Gallery.