Ladizinski, Barry MD; Lee, Kachiu C. MD; Wilmer, Erin; Alavi, Afsaneh MD, FRCPC; Mistry, Nisha MD; Sibbald, R. Gary BSc, MD, MEd, FRCPC (Med) (Derm), FACP, FAAD, MAPWCA
Psoriasis is a chronic inflammatory skin disorder that affects an estimated 2% of the world’s population.1 It encompasses a spectrum of disease with several clinically distinct subtypes. The variants that will be discussed in this article include chronic plaque psoriasis (CPP), intertriginous psoriasis (IP), pustular psoriasis (PP) that is localized (often palms and soles) or generalized, erythrodermic psoriasis (EP), and guttate psoriasis (GP).
The disease onset can occur at any age, but a bimodal age distribution has been described with peaks at 20 to 30 years of age and at 50 to 60 years of age.1 The etiology of psoriasis is complex, involving genetic, immunologic, and systemic/local triggering factors. A large questionnaire survey found a positive family history in 36% of affected patients,2 and several genetic loci have been implicated in psoriatic pathogenesis. In addition, aberrations in cellular function (T cells, endothelial cells, keratinocytes, and macrophages) and cellular products (cytokines and adhesion molecules) contribute to the development of psoriasis.3,4 Systemic and external local triggering factors vary with the individual and the subtype of psoriasis as reviewed in the following discussion.
Reading this article will help the clinician to identify the types of psoriasis, understand its etiology, and initiate appropriate treatment.
Psoriasis is a systemic disease associated with a number of comorbidities. Perhaps the most recognized extracutaneous manifestations are nail psoriasis and psoriatic arthritis. In a large study, nail involvement was observed in 80% of psoriatic patients (see Figure, Nail psoriasis photo).5 Psoriasis affects the nail matrix, bed, plate, and hyponychium (epithelium between the nail bed and nail plate). Psoriatic nail findings include the following:
- pitting—loss of surface immature keratin, leaving a hole in the nail
- onycholysis—distal separation of the nail bed from the nail plate with a white discoloration (leukonychia)
- oil spots—immature keratin in the nail plate giving a yellow discoloration, distinctive from the normal pink color and resembling oil drops
- subungual hyperkeratosis and dystrophy—this is a buildup of immature keratin between the nail bed and nail plate, leading to thickened distal nails that may extend to involve the entire nail plate.
Nail psoriasis is commonly misdiagnosed and treated as onychomycosis. Although a positive potassium hydroxide (KOH) examination and/or culture of debris from under the nail plate are required for a fungal infection of the nail diagnosis (onychomycosis), this diagnosis can be superimposed on a deformed psoriatic nail. Nail changes are more common, however, in persons with psoriatic arthritis.6
Psoriatic arthritis, a seronegative inflammatory arthritis, affects 7% to 26% of patients with plaque psoriasis7 and is a major contributor to the economic burden of psoriasis.8 The most common pattern of arthritis affects the distal joints, especially the fingers and toes in an asymmetric pattern with a few joints involved (distal oligoarthritis). The soft tissue of the digits may become swollen, producing a sausage-like digit that is usually acutely painful. This is referred to as dactylitis. (see Figure, Dactylitis photo). Less common forms of psoriatic arthritis patterns include polyarthritis (rheumatoid factor negative), sacroiliitis, ankylosing spondylitis, and distal resorption of the fingers with arthritis mutilans. Aside from nail changes and psoriatic arthritis, psoriasis has also recently been associated with an increased risk of depression, alcoholism, obesity, insulin resistance, dyslipidemia, hypertension, myocardial infarction, and Crohn’s disease.9–11 These associations have significant implications for the counseling and treatment of patients diagnosed with psoriasis.
ASSESSMENT AND DIAGNOSIS
The diagnosis of psoriasis is often based solely on physical examination. After examining the primary skin eruption, further examination of commonly involved sites is often helpful in confirming the diagnosis. Erythema and dry white-silver scaling on the scalp (discrete plaques that often extend beyond the scalp margin) can help differentiate psoriasis from the diffuse, indistinct greasy scale of seborrhea. Psoriasis is also common behind the ears and in and around the umbilicus; nail changes tend to be more common with psoriatic arthritis.6 The skin should also be examined for linear plaques that indicate Koebnerization, a phenomenon in which psoriatic plaques arise 1 to 2 weeks after local trauma.12 This phenomenon is important in wound care, as psoriatic lesions may form under compression bandages, skin covered by ostomy appliances (see Figure, Periostomal psoriasis photo), and on the periwound skin. The wound care specialist should be familiar with the morphology of psoriatic lesions and the differential diagnosis of a periwound rash on the lower extremities. A history of previous psoriasis or a family history of psoriasis can also help with diagnosis. If the diagnosis is in doubt, however, a routine skin biopsy, usually a punch biopsy, is a simple and effective way to confirm the diagnosis.
CHRONIC PLAQUE PSORIASIS
Chronic plaque psoriasis is the most common variant of psoriasis, characterized by well-defined, erythematous plaques with adherent silvery scale (see Figure, Plaque psoriasis). The scalp, extensor surfaces of the elbows and knees, lumbosacral area, and intergluteal cleft are preferential sites of involvement. The course of CPP is chronic with periods of exacerbation and remission. The involved body surface area can vary from minimal to extensive. Precipitating factors may include stress, infection, medications (particularly antihypertensive β-blockers, lithium, antimalarials, interferon), and local trauma (Koebner phenomenon). Depending on plaque size, location, and extent of lesions, the differential diagnosis may include atopic dermatitis; other forms of eczema, particularly chronic nummular lesions; seborrheic dermatitis; lichen simplex chronicus (eczema due to scratching or rubbing); mycosis fungoides (cutaneous T-cell lymphoma); drug reactions; and squamous cell in situ (Bowen disease).
Psoriasis severity can be categorized according to the Psoriasis Area and Severity Index (PASI) or the Physicians Global Assessment (PGA).4 The PASI measures the sum of both the severity of the psoriasis and the percentage involvement of each body region (head, arms, trunk, and legs). The severity of the average lesion is measured with a 4-point scoring system, documenting erythema, scale, and the thickness of the plaques (infiltration). The PGA measures psoriasis on a 7-point scale from clear (0) to very severe (6). Both of these indices fail to consider the psychosocial impact of the disease. Evaluative tools for assessment of psychosocial well-being include the Psoriasis Life Stress Inventory and Psoriasis Disability Index.13 The degree of pruritus and visibility of lesions should also be considered when assessing severity, as these contribute to the psychological impact of the disease.14
As plaque psoriasis is a chronic disorder, treatment is aimed to control, not cure, the disease. It is important to discuss realistic expectations for treatment outcomes with patients, as well as their preferences. A number of topical regimens can be time consuming, greasy, or malodorous. Patients should receive clear explanations regarding proper application of the selected agent. For example, greasy topical preparations and those containing tar derivatives should be applied in a linear fashion in the direction of the hair follicle to avoid folliculitis.
Agents used in the treatment of CPP are divided into 5 main categories:
- topical agents (eg, corticosteroids, vitamin D derivatives, topical vitamin derivatives—retinoids, tar, salicylic acid, and petrolatum)
- intralesional steroid injections12
- phototherapy and photochemotherapy
- traditional systemic medications (eg, sulfasalazine, acitretin, methotrexate, cyclosporine)(Table 1)
- newer biologic agents (eg, adalimumab, etanercept, ustekinumab) (Tables 2 and 3)
Indications for each treatment modality are summarized in the sidebar The Heartbreak of Psoriasis.
Topical agents are the mainstay of psoriasis treatment for limited disease severity (usually <10% of the body surface area). A good way to measure the extent of involvement is to picture the area affected by psoriasis fitting into the palms of the patient’s hands, with each palm representing about 1% of the total body surface.
Approximately 80% of patients with psoriasis have mild to moderate disease that can be treated with topical medications. Topical corticosteroids are first-line therapy for the majority of patients and can be used as monotherapy or in combination with other topical medications, phototherapy, or systemic medications. Disease severity, location of involvement, patient age, and patient preference should be considered when choosing the potency of the topical steroid and vehicle (lotion, cream, ointment, gel), as ointments are more occlusive and more effective than lotions, creams, and gels.15
Low-potency steroids are best (1–3× hydrocortisone, based on the author’s [R.G.S.] calculation of vasoconstriction assay data and the ability to produce atrophy. These include hydrocortisone 1% as the baseline and hydrocortisone valerate 0.2%, desonide 0.05%, or mometasone furoate 0.1% as 3 times more potent) for the face and body folds or general trunk/extremity skin for infants/young children. Thick psoriatic plaques often require topical steroids in the 6× to 9× hydrocortisone range (6× with betamethasone valerate 0.1%, or amcinonide 0.1% or 9× with fluocinonide 0.05% or triamcinolone acetonide 0.5%), and the palms and soles may require 12× hydrocortisone preparations (clobetasol propionate 0.05% and betamethasone dipropionate 0.05%) (see The Heartbreak of Psoriasis). Ointments (best used at night) are more effective than creams. Lotions or gels are preferred vehicles for the scalp and creams for body folds. After about 2 weeks, the maximum effect of a topical corticosteroid used alone may be reached, and steroid-sparing, synergistic topical therapies should be coadministered (eg, topical steroid in the daytime and the steroid-sparing agent at night).
Vitamin D analogs (eg, calcitriol, calcipotriol, and tacalcitol) can be used as monotherapy or in combination with topical corticosteroids for added benefit and steroid-sparing effect.12 Tazarotene, a topical retinoid, is also best used in combination with a topical corticosteroid. Salicylic acid (2%–10%) is a keratolytic (removes scale) used to soften psoriatic plaques and enhance penetration of topical steroid preparations. A less messy coal tar derivative, liquor carbonis detergens, can be mixed with topical steroids in concentrations of 5% to 10% as a steroid-sparing measure.
Emollients, especially petrolatum-containing products, are considered a standard part of treatment, utilized to retain moisture in the stratum corneum, and they will increase the local penetration of topical steroid preparations. Petrolatum ointment bases also have an antipsoriatic effect and can be alternated with gradual withdrawal of topical steroids for the maintenance stage of topical plaque psoriasis treatment. Coal tars, although effective, are less frequently used in current practice because of their malodorous nature, associated folliculitis, and propensity to stain skin and clothing.5
Topical calcineurin inhibitors are occasionally used (eg, tacrolimus and pimecrolimus) and have large molecules, so they do not penetrate the skin as readily as topical corticosteroids and are therefore recommended for use on thin-skinned areas, such as the body folds.
Small, resistant plaques of psoriasis may respond to intralesional steroid injections. Triamcinolone is most commonly used, with a concentration of 2.5 to 10 mg/mL injected into the mid-dermis of psoriatic plaques with a maximum of 2 to 3 mL of local injections every 6 to 8 weeks. Small amounts (0.1- to 0.2-mL aliquots) of the topical steroid (diluted to the above concentrations with xylocaine, saline, or sterile water) are injected into the mid-dermis with a spacing of approximately 1 cm between injection sites.
Phototherapy is an integral aspect of psoriasis treatment used for both extensive disease and for limited disease with debilitating symptoms. Ultraviolet light is locally immunosuppressive but typically lacks the systemic immunosuppression encountered with traditional oral antipsoriatic drugs and biologic agents. All candidates for phototherapy or photochemotherapy should undergo a complete history and physical examination. Systemic lupus erythematosus and xeroderma pigmentosum are absolute contraindications to phototherapy, whereas extensive photodamage, photosensitivity disorders, history of melanoma, atypical nevi, and immunosuppression (especially organ transplantation), among others, are relative contraindications.16 A history or suspicion of porphyria is also a contraindication for phototherapy. Persons with blonde or red hair or freckles and who always sunburn but never tan generally should not have phototherapy. If they do, low doses should be administered with extreme caution.
Phototherapy often consists of traditional ultraviolet B (UVB) therapy. The cumulative dose administered needs to be calculated and the skin monitored, with treatments often 3 to 5 times a week. Narrow-band UVB may provide a faster response rate than traditional UVB light with a lower total number of joules of energy required for a response. Ultraviolet A (UVA) penetrates deeper into the skin and is combined with the administration of a topical or systemic psoralen that acts as a photosensitizer to increase the local effect of the UVA treatments. This band length is associated with pigment darkening and an increased long-term incidence of squamous cell carcinomas.
The 5 most commonly used traditional systemic medications are sulfasalazine, acitretin, methotrexate, oral psoralens combined with UVA light (PUVA), and cyclosporine. These agents should be considered when suboptimal response has been achieved from the use of topical steroids, steroid-sparing topical agents, intralesional steroids, or phototherapy. Sulfasalazine and acitretin have a low adverse effect profile with significant reduction in the PASI.17 Sulfasalazine has been associated with allergic drug reactions, and gastrointestinal intolerance may be limiting factors.
Acitretin is an effective systemic agent that complements topical treatments and can be used with phototherapy.18 Patients should be monitored for hypertriglyceridemia and dry eye, nose, mouth, and skin. Given the possibility of teratogenicity, acitretin should not be used in women of childbearing potential; 13 cis-retinoic acid can be considered for short periods as an alternative but should be combined with oral contraceptives and not used in pregnant patients. In addition, acitretin may delay the occurrence of skin cancers related to previous phototherapy or other sources of photodamage. Sulfasalazine may help psoriatic arthritis, but acitretin does not benefit arthritis symptoms.
Methotrexate can treat psoriatic arthritis symptomatically, often with lower doses than needed for skin clearing (0.2–0.4 mg/kg per week in a single dose). Patients must be carefully monitored for myelosuppression (low hemoglobin, white blood cell count, platelets) and hepatotoxicity when on methotrexate. Cyclosporine can be used in low doses (3–5 mg/kg per day) for 1 to 2 years, and patients should be monitored for nephrotoxicity, hypertension, and potential drug interactions. Oral psoralens can also photosensitize the skin and when combined with UVA light decrease the amount of light needed for a therapeutic response.
Biologic agents are the newest class of antipsoriatic agents (Tables 2 and 3). They are considerably more costly than traditional systemic agents, and drug plan coverage is important to consider before prescribing these agents. Biologic agents are indicated if more than 10% of the body is involved with psoriatic plaques, and an individual has failed on 2 or more systemic agents. Biologic agents (Tables 2 and 3) can be categorized into 3 main groups: (1) anti-T cells (eg, alefacept and efalizumab), (2) tumor necrosis factor α inhibitors (eg, adalimumab, etanercept, infliximab, ustekinumab), and (3) interleukin-12 and interleukin-23 inhibitors (ustekinemab). On the PASI scale, all biologic agents demonstrated efficacy in reducing moderate to severe psoriasis after a 12-week period of use as compared with placebo.18 Biologic agents target the immune system; therefore, patients must be periodically monitored for symptoms of infection and malignancy.19 These therapies are generally considered safe, but rare, serious adverse effects, such as infections, reactivation tuberculosis, malignancy, and demyelination of nerve fibers, have been reported.20,21
Intertriginous psoriasis (see Figure, Intertriginous psoriasis photo), also known as inverse psoriasis or flexural psoriasis, is characterized by thin, sharply demarcated, shiny erythematous plaques. Scale is minimal to absent, and as the name suggests, typical locations include the axillae, behind the ears, under the breast, intergluteal cleft, and inguinal crease.
Other causes of intertrigo that should be distinguished from IP include Candida intertrigo, erythrasma, fungal infection, seborrheic dermatitis in infants, and contact allergic or irritant dermatitis.22 Bacterial culture and sensitivity can be obtained if secondary bacterial infection (impetiginized crusts or local pain with secondary perianal cellulitis) is suspected, as Staphylococcus or Streptococcus is known to colonize psoriatic skin lesions.23 Microscopic KOH examination of surface scale (red annular border with central clearing) can distinguish IP from a fungal infection of the groin (tinea cruris).
Erythrasma presents with hyperpigmented, slightly erythematous, and scaly plaques due to corynebacterial infection. The involved skin will fluoresce coral red under Wood light examination, whereas tinea versicolor has a yellow fluorescence. Evaluation for seborrheic dermatitis and contact irritant or allergic dermatitis is usually confirmed on history or with examination of lesions elsewhere. Occasionally, the application of a suspected topical contact allergen to a normal patch of skin (the size of a silver dollar twice a day for 2 or 3 days) on the forearm below the elbow crease will confirm a diagnosis of contact allergy, and the specific agent can be confirmed with patch tests of the components in the topical preparation. A skin biopsy is occasionally required if the clinical presentation of an intertriginous eruption is not diagnostic and more unusual etiologies, such as lichen planus, are suspected.
Management of IP involves short-term treatment (2-4 weeks) with low- to mid-potency topical steroids. The frequency of application can be tapered and ultimately discontinued if the psoriasis improves. Frequent, long-term use of topical steroids in fold areas can result in atrophy, striae, and telangiectasias. For continued therapy beyond 2 to 4 weeks, other topical options (calcipotriene, calcitriol, pimecrolimus, or tacrolimus) should be initiated; alternatively, low-dose topical steroids can be used once or twice weekly for maintenance therapy.24
PUSTULAR PSORIASIS: LOCALIZED AND GENERALIZED
Pustular psoriasis is an uncommon manifestation of psoriasis characterized by an eruption of sterile pustules. Four patterns, 3 generalized and 1 localized, have been proposed:
- The von Zumbusch pattern is characterized by abrupt onset of erythema, pustule formation, and fever, followed by pustule resolution and extensive scaling. This form of psoriasis may be life threatening.
- Annular pattern consists of erythematous, scaly, annular lesions with pustules at the annular advancing border.
- The exanthem type presents as an acute eruption of small pustules that resolve within days often without systemic symptoms.13 If systemic symptoms are present, they include recurrent fever followed by a new wave of pustule formation, weakness, and weight loss.25
- The localized pattern (see Figure, Localized pustular photo), in which pustules appear predominantly on the palms or soles and often within or at the periphery of psoriatic plaques. This condition is more common in women, especially smokers. Smoking cessation may improve the clinical symptoms and signs.
Risk factors for PP include infections, pregnancy (historically referred to as impetigo herpetiformis and now more commonly called PP of pregnancy), oral corticosteroid therapy (relatively contraindicated in persons with psoriasis), hypocalcemia, stress, and irritating topical therapy.21 The most important differential diagnosis is acute generalized exanthematous pustulosis (AGEP). This condition is an acute, febrile drug reaction characterized by small, sterile pustules with a background of erythema. Unlike generalized pustular psoriasis (GPP), AGEP is often associated with intense pruritus and other skin manifestations, such as vesicles (fluid-filled blisters less than a cm), purpura, and erythema multiforme–like lesions. In addition, AGEP typically occurs within 1 to 2 days following ingestion of the offending drug. A skin biopsy may also help differentiate GPP and AGEP.21
A 2012 task force of the National Psoriasis Foundation Medical Board26 recently issued a consensus paper on the treatment of PP. According to this report, first-line therapies include cyclosporine, methotrexate, and acitretin with psoralens plus ultraviolet A (PUVA) and the biological agents’ (infliximab, etanercept, and adalimumab) are considered second-line agents. The authors stress that disease severity and patient comorbidities should govern therapeutic decision making, as factors such as teratogenicity need to be considered.26
Erythrodermic psoriasis (EP) (see Figure, Erythrodermic psoriasis) is a rare but potentially life-threatening form of psoriasis characterized by generalized erythema and scaling. It may occur in patients with preexisting psoriasis or present de novo as the initial sign of psoriasis. Precipitating factors include excessive application of topical steroids, withdrawal from systemic steroids, systemic illness, emotional stress, phototherapy burns, alcoholism, and irritating topical therapy.27
Erythrodermic psoriasis can be acute or chronic with variable severity; some patients present with a rapid, intense onset that necessitates hospitalization and aggressive intervention, whereas others experience a protracted, waxing-and-waning course. Nail involvement, if present, ranges from mild pitting to severe dystrophy. The most common systemic findings include fever, chills, malaise, fatigue, weight loss, pruritus, and peripheral edema.27 Depending on the extent of exfoliation, complications such as dehydration, protein loss, hypothermia, and infection may occur.
The differential diagnosis of EP encompasses other causes of generalized erythroderma, including contact allergic dermatitis, atopic dermatitis, and drug reactions, along with a number of less common causes (pityriasis rubra pilaris, sarcoidosis, infections, seborrheic dermatitis [especially in infants], and erythrodermic cutaneous T-cell lymphoma). A personal or family history of psoriasis, presence of plaque-type psoriatic lesions previously, psoriatic nail changes, and inflammatory arthritis suggest a diagnosis of EP. If the diagnosis is uncertain, punch skin biopsies (2 or 3 sites may be required) should be performed.28
Erythrodermic psoriasis is a rare disorder, and data on the efficacy of treatment options are consequently limited. According to a 2010 task force of the National Psoriasis Foundation27 Medical Board, first-line therapy for severe, acute cases includes the rapidly acting agents cyclosporine and infliximab. Methotrexate and acitretin are other first-line agents, but their slightly delayed onset of action renders them appropriate for less acute cases or for patients with a contraindication to cyclosporine or infliximab. Combination therapy (concomitant use of 2 of the aforementioned agents) may also be considered for severe or refractory disease.27 Evidence for the efficacy of biologics in the treatment of EP is limited to case reports and case series, with the exception of 1 multicenter, retrospective study that compared outcomes in 28 patients.29 In this study, 48% of cases treated with infliximab, 50% of cases treated with adalimumab, and 40% of cases treated with etanercept reported greater than 75% improvement based on the PASI scores.29
Regardless of the systemic therapy chosen, patients should be closely monitored for signs of infection, high output cardiac failure, malabsorption, anemia, and decreased liver/renal function. Supportive care may include warming blankets (as these individuals tend to lose thermoregulation), topical emollients (only expose a local region of the body at any time), sequential wet compresses or soaks, or oatmeal baths followed by emollient or other topical applications.29,30 Topical steroids (low potency for the face and intertriginous folds, and medium potency for the trunk and extremities) may be used, but high-potency topical steroids are best avoided as they can exacerbate erythroderma and may lead to adrenal insufficiency, especially on withdrawal.29 It is recommended that disease severity and comorbidities guide the treatment strategy.28
Guttate psoriasis typically manifests as an acute eruption of monomorphic, pink, oval papules with silvery scale on the trunk and extremities of adolescents and young adults. Like EP, GP can present as an acute flare of established psoriasis or as a harbinger of occult psoriatic disease in adolescents or young adults. Also similar to EP, GP can assume an acute or chronic form.30 Few studies have examined the clinical course of GP, but recent evidence suggests that 33% to 38% of patients progress to CPP.30,31 Although older individuals are less often affected, they appear to have a less favorable outcome with higher rates of progression to chronic disease.31 Nail involvement and arthritis are less common in GP compared with non-GP, affecting only 3% and 11%, respectively, of patients with GP versus 27% and 32% of patients with non-GP.32 The most commonly reported systemic symptom is pruritus.30
Other diseases that mimic GP include pityriasis rosea, nummular eczema, secondary syphilis, drug reactions, and viral rashes.33 Risk factors for an initial episode of GP include a family history of psoriasis, emotional stress, and recent streptococcal pharyngitis.34 An association between GP and an elevated antistreptolysin O titer or infection with Streptococcus pyogenes is well established in the literature, although a pathogenic mechanism that links these entities has yet to be elucidated. Evidence suggests that antistreptococcal therapies do not confer a therapeutic advantage in the treatment of GP.34–38 In addition, the development of scarlet fever or poststreptococcal sequelae in patients with GP has not been reported.37
There is no consensus on the optimal treatment for GP and no published trials examining efficacy of commonly used topical therapies or phototherapy.41 Thus, the therapeutic armamentarium for GP mirrors that of plaque psoriasis. Tar preparations, topical corticosteroids, vitamin D analogs, and phototherapy are frequently used, although comparative data are lacking.39
PSORIASIS FOR THE WOUND CARE SPECIALIST
Protection and effective management of periwound skin are an integral component of wound healing. It also poses a significant challenge for wound care specialists and is of major concern for patients. Periwound skin is a vulnerable area for psoriatic patients because of the Koebner phenomenon, where traumatized skin more easily flares with psoriasis 1 or 2 weeks later. Maceration of the skin (due to overhydrating the stratum corneum keratin) by wound exudate and skin stripping due to adhesive dressings is also a source of skin damage and trauma. Liquid barrier films (film-forming liquid acrylates) can be used as a protective but flexible coating to cover tissue at risk of maceration. Several small-scale studies have demonstrated the efficacy of these films in decreasing epidermal stripping when wound-dressing adhesives are removed.40,41 Other options include petrolatum, zinc oxide ointment, or windowed adhesive dressings.
Peristomal psoriasis is also a common problem (see Figure, Periostomal psoriasis photo), and psoriasis in this region is associated with chronic moisture and irritation. Topical or intralesional corticosteroids can be used for treatment of peristomal psoriasis, as well as selecting an adhesive that minimizes trauma.42 In order to protect the adhesion of the ostomy wafer, intralesional corticosteroids are often useful if a normal wear time of 5 to 7 days is expected; topical steroids in the form of a spray or lotion are often better suited to having an appliance applied with adhesive over the local site. To avoid atrophy, the intralesional steroid applications should be repeated no more frequently than every 4 to 6 weeks. Topical applications are also infrequent with moderate to potent steroids if applications are only with appliance change every 3 to 7 days. Clinicians should be aware that preparations with high alcohol content will often burn and sting with application to open skin with erosions or ulceration.
In a consensus statement regarding management of peristomal and periwound moisture-associated dermatitis, prevention was emphasized as a critical step in management of these patients. Stool leakage is a major causative factor in peristomal dermatitis and psoriasis. Prevention of leakage through use of an appropriate pouch system is critical to resolving the problem. The opening of the skin barrier device must also be individualized. This can be accomplished through cutting the device into the size and shape of the stoma. The use of a convex rather than a flat appliance can also be considered if the stoma lumen is below skin level or if the stoma is located in an area in which skin folds or creases obstruct the area when sitting or performing daily activities of living. Skin barrier paste, strips, rings, powder, and belts can also be used to optimize placement of the skin barrier and decrease local trauma and subsequent appearance of psoriasis with the Koebner phenomenon.43
Psoriasis in the orthopedic patient presents unique challenges. In postsurgical patients with psoriasis, infection rates can range from 17% to 21% postarthroplasty.44 In a series of 27 psoriatic patients undergoing arthroplasty, 11% developed immediate postoperative complications related to a severe exacerbation of psoriasis or skin necrosis.44 Patients with psoriatic arthritis undergoing orthopedic foot surgery also had higher rates of postoperative infections (9.1%) compared with those with osteoarthritis and rheumatoid arthritis.45
Psoriasis can be present with leg ulcers as a bilateral lower-extremity eruption with or without coexisting vascular disease. The differential diagnosis includes stasis dermatitis and contact dermatitis. These chronic skin outbreaks and associated venous, mixed, or arterial leg ulcers can have a significant impact on quality of life, with the majority of patients experiencing pain, reduction in outdoor mobility, and difficulty with finding appropriate footwear.46 Treatment includes high compression therapy in the absence of arterial disease (ankle brachial pressure index [ABPI] >0.8) or modified compression with mixed venous and arterial disease (ABPI 0.6–0.8) to control the edema, which will also help to improve the psoriasis. Because an abrasive contact layer dressing adhesive may trigger the Koebner phenomenon, nonadhesive or soft silicone products should be utilized. Therefore, the wound care physician must monitor the patient frequently to determine the appropriate treatment.
In summary, psoriasis can present in multiple forms: chronic plaques, intertriginous, pustular, erythrodermic, and guttate subtypes. Systemic associations include arthritis with the skin and joint disease having psychological sequelae. A thorough history and physical examination at the time of presentation should document the extent, severity, and subtype(s) of psoriasis. The examination should also include examination of the scalp, nails, and intertriginous skin.
Multiple topical and systemic treatment options are available, and therapy should be directed according to the type and severity of psoriasis. Mild to moderate psoriasis can often be treated with topical steroids and steroid-sparing topical agents that may need to be supplemented with intralesional steroids or ultraviolet light. Systemic drugs (>10% body surface area) and biologic agents (>10% and failure of 2 systemic treatments) are typically reserved for those with moderate to severe presentations with inadequate topical therapy responses.
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