Chapter 9: Psoriasis and Other Papulosquamous Diseases

Psoriasis, seborrheic dermatitis, pityriasis rosea, and lichen planus are diseases that present with papulosquamous lesions (scaly papules and plaques). Although these diseases may have a similar morphology, their underlying etiologies vary. Secondary syphilis, cutaneous T-cell lymphomas, and connective tissue disease may also present with papulosquamous lesions and should be included in the differential diagnosis.

Introduction

Psoriasis is a common, chronic, inflammatory disease that can result in decreased quality of life. Clinicians have long been vexed by this ancient affliction. Although most medical literature prior to Willan (1757-1812) lumped psoriasis, leprosy, eczema, and other inflammatory dermatoses into a confusing menagerie, Celsus gave a convincing account of psoriasis vulgaris almost 2000 years ago. His description included many of the morphologic features that physicians today utilize to diagnose psoriasis, including the "ruddy" or salmon-colored plaques with silvery scales that often are associated with punctate hemorrhage or "erosions" when removed.¹

More than 7.5 million adults (2.1% of the population) in the United States are affected and 30% of these individuals will develop psoriatic arthritis.² About 1.5 million of them are considered to have moderate to severe disease. Psoriasis may have a significant negative impact on a patient's quality of life. Patient often are self-conscious, depressed, or frustrated over the appearance of their skin.

Psoriasis spans all socioeconomic groups, and its prevalence varies by geographic location. Historically, the disease is more common in the northern latitudes. The rate of psoriatic disease is lower in African Americans compared with that in European Americans.²

Pathophysiology

The primary cause of psoriasis is a dysregulation of the cell-mediated, adaptive immune response. This dysregulation is likely triggered by hyperactivity of the innate immunological surveillance system to environmental antigens. In genetically predisposed individuals, the Th1 pathway response is overstimulated. This overproduction of Th1-related cytokines along with IL-12, 17, and 23 causes hyperproliferation of epidermal keratinocytes. These events lead to the formation of the psoriatic plaques.³

Environmental factors and disease states that interact with polygenic inheritance patterns most likely account for the variable expression of psoriatic disease. These include streptococcal pharyngitis (guttate psoriasis), stressful life events, low humidity, human immunodeficiency virus (HIV), trauma, medications, cold, and obesity. Diets high in fish oils seem to be protective against the development of psoriasis.^2,4

Clinical Presentation

History

Most patients with mild to moderate psoriasis are asymptomatic, but pruritus is common in severe or widespread disease. Patients may also give a history of joint pain and swelling, especially in the fingers and toes.

Physical Examination

Psoriasis can vary in appearance and distribution. However, there are clues in the physical examination that allow the clinician to properly diagnose psoriasis and identify its subtypes.

• Plaque-type psoriasis vulgaris accounts for 90% of all cases. The primary lesion is a scaly, red- to salmon-pink-colored papule that expands centrifugally to form a similarly colored plaque (Figure 9-1). It is usually covered by a white or silvery scale that, when removed, may show pinpoint bleeding (Auspitz sign). Its border may be red and with time central clearing may occur, with the plaques taking on an annular or arcuate configuration. Plaque-type psoriasis is classically an extensor disease often involving the knees, elbows (Figure 9-2), gluteal cleft, lumbosacral region, and the umbilicus. Psoriasis may involve the scalp (Figure 9-3). Psoriatic plaques may occur in an area after trauma, pressure, or injury. This is known as the Koebner phenomenon.

• Inverse psoriasis presents with thin pink plaques with minimal scale in the axillae (Figure 9-4), inguinal and inframammary area, and body folds of the trunk. It may occur in conjunction with typical plaque psoriasis or it may be the only manifestation of psoriasis.

• Guttate psoriasis occurs in less than 2% of cases, but it is a common psoriatic subtype in young adults. It is characterized by small "droplet-like" thin pink to salmon-colored papules and plaques surmounted by a fine white scale (Figure 9-5). The distribution is often similar to that of classic pityriasis rosea, favoring the trunk, abdomen, and upper thighs and fading toward the acral surfaces and sparing the palms and soles.

• Pustular psoriasis (von Zumbusch) is an acute variant of the disease that presents with small, monomorphic sterile pustules surmounting painful, inflamed, erythematous papules. Fever, systemic symptoms, and an elevated white blood cell count often accompany generalized pustular psoriasis. Acral pustules, usually without systemic symptoms, characterize palmoplantar pustulosis (Figure 9-6), which is a milder, but more common presentation of pustular psoriasis.

• Erythrodermic psoriasis is a skin reaction pattern of total body redness and desquamation of the skin. There are many causes of erythroderma and it is not specific to psoriasis. The massive shedding of skin that occurs during an erythrodermic flare of psoriasis can result in infection, hypothermia, protein loss, hypoalbuminuria, dehydration, and electrolyte disturbances.⁴

• Psoriatic nails can be seen in up to 50% of patients with psoriasis. It may be the only manifestation of psoriasis. It is recognized that nail disease is more closely linked with psoriatic joint disease. Up to 90% of patients with psoriatic arthritis have nail disease.⁴ Nail dystrophies associated with psoriasis include pitting, onycholysis (nail plate separation), oil spots (yellow-orange subungual discoloration), thickening, and subungual debris (Figure 20-3). Splinter hemorrhages may also be present.

Laboratory Findings

Blood work is generally not necessary to make a diagnosis of psoriasis. Pustular flares of psoriasis during pregnancy may be associated with hypocalcemia. A biopsy is often helpful if the diagnosis is unclear. A punch biopsy of a plaque or pustule often supports the diagnosis. A biopsy is warranted in any patient not responding as expected to traditional therapy. The microscopic findings of common plaque-type psoriasis are epidermal hyperplasia, parakeratosis, thinning of the granular layer, epidermal infiltration of neutrophils, and occasional "Munro abscesses" (intraepithelial collections of neutrophils).

Diagnosis

The key diagnostic clinical features of psoriasis are red to pink plaques with silvery white scale on the elbows, knees, scalp, and lower back and legs.

Differential Diagnosis

• ✓ The differential diagnosis of psoriasis includes other papulosquamous diseases (Table 9-1).

Management

Topical steroids are the first-line treatment of mild to moderate psoriasis. They act as a foundation on which to build a therapeutic regimen for more severe disease. While topical regimens demonstrate efficacy in clinical trials, the response to these agents in everyday practice is often variable. Frequently, this is a result of poor compliance. Ointments are the most effective vehicles for psoriasis, but they stain clothing and bedding. Creams are better patient-accepted vehicles for the face, neck, and hands. Solutions and foams are appropriate for the scalp. Table 9-2 contains commonly used topical medications for psoriasis.

It is often advisable to begin therapy with one simple agent. In plaque-type psoriasis, superpotent topical steroids, such as clobetasol or betamethasone, are usually necessary to treat thick plaques.⁴ Scalp disease requires ultrapotent steroids in solution or foam vehicles. A simple regimen utilizing clobetasol or betamethasone twice a day for 2 to 4 weeks is an easy way to achieve efficacy. With time, the patient can move to an alternating regimen of vitamin D analogues, such as calcipotriol (calcipotriene) or calcitriol. These medications can be alternated by day (calcipotriol Monday to Thursday and clobetasol Friday to Sunday) or by application (calcipotriol in morning and clobetasol at bedtime). Topical vitamin D analogues may cause hypercalcemia; therefore, the weekly dose should be under 100 mg. A less potent topical steroid and more cost-effective agent such as triamcinolone, when utilized regularly, may be more effective than higher potency steroids. After finding the preferred vehicle and topical regimen for a patient, closely spaced follow-up visits improve adherence and will give the clinician opportunity to encourage continued compliance, and fine-tune the regimen based on the patient's condition.

In areas of thin skin such as the face, neck, axillae, groin, genitals, and body folds, lower potency steroids such as hydrocortisone 2.5%, desonide, and hydrocortisone valerate 2.5% are useful.⁵ Vitamin D analogues such as calcipotriene have traditionally not been used in these areas due to their tendency to cause inflammation.

Topical calcineurin-inhibiting agents are also quite useful for therapy of psoriasis.⁶ Tacrolimus ointment (0.1% for adults, 0.03% for children) may burn a bit on application, but seems to have slightly more efficacy than topical pimecrolimus. Because these medications are not corticosteroids, they do not cause skin atrophy, glaucoma, or many other steroid-related side effects. Thus, they are an effective, safe way to treat psoriasis on the face, in the skin folds, and around the eyes. In the United States these medications are Food and Drug Administration (FDA) approved only for atopic dermatitis and carry a black box warning for lymphoma.

Tazarotene (gel or cream, 0.05% or 0.1%) is a retinoid. It can be used as a steroid-sparing agent in a manner similar to the vitamin D analogues. This agent tends to cause more inflammation than calcipotriene. Therefore, patients may find that tazarotene fits best into their regimen when applied in conjunction with topical steroids. Tazarotene is in pregnancy category X.

In the setting of hyperkeratotic, scaly plaques there may be a role for keratolytics to remove scale and facilitate penetration of the topical steroid and/or vitamin D analogue. Salicylic acid, urea, and lactic acid are agents that can be added to a regimen for this purpose. Salicylic acid comes as a cream, gel, cream, or shampoo in concentrations that range from 2% to 10%.

Topical coal tar products have an anti-inflammatory effect in psoriasis and can be used in conjunction with topical steroids and keratolytic agents. Examples of tar products include Estar, Fototar, PsoriGel, and Neutrogena T/Derm Tar Emollient.

Emollients may aid treatment of psoriasis. They can improve efficacy and lower the economic burden of other topical agents by softening the stratum corneum through hydration and reduction of superficial scale. A daily bath in warm water, followed by application of petrolatum and supplemented by 2 or 3 further applications of a moisturizer during the day, is a beneficial addition to any treatment regimen.⁴

Pediatric Psoriasis

There is a dearth of evidence regarding treatment of psoriatic disease in children. The lack of good, double-blinded, placebo, controlled trials is not specific to psoriasis treatment, but it does make foretelling the future consequences of one's therapeutic decisions in this population quite difficult. Most of the principles discussed above with regard to adults still hold for the pediatric population. In the pediatric population one must, of course, consider long-term side effects due to lengthy exposure to immunomodulators.

Psoriatic Arthritis

Every patient with psoriasis should be specifically screened for joint disease and enthesitis (inflammation of the tendon insertions).⁴ History of morning stiffness, joint tenderness, swelling, sausage digits, and involvement of the peripheral small joints is characteristic. The hands are the most common site of involvement. Enthesitis usually occurs at the insertion sites of the Achilles tendon, the plantar fascia, and ligamentous attachment points of the rib, spine, and pelvis. Musculoskeletal involvement can present at any time, but most often between the ages of 30 and 50 years.

Comorbidities in Patient with Psoriasis

Psoriasis is an independent risk factor for atherosclerosis, coronary artery disease, myocardial infarction, stroke, and cardiovascular mortality. Patients with psoriasis are more likely to have other cardiovascular risk factors such as diabetes, hypertension, dyslipidemia, tobacco use, and obesity.^4,7

Potential Causes of Flares of Psoriasis

Group A beta-hemolytic streptococci infection can act as an environmental trigger for guttate psoriasis particularly in the pediatric population.⁴ Many clinicians will obtain an antistreptolysin-O, antihyaluronidase, anti-DNase-B, and streptozyme titer along with streptococcal cultures of the throat and perianal area as part of the initial workup of pediatric psoriasis. Other commensal organisms on the skin may play a role in specific variants of psoriasis. Management of these microbes can be an adjunct to psoriatic treatment.

Common medications that may exacerbate psoriasis include beta-blockers, ACE inhibitors, nonsteroidal anti-inflammatory drugs, lithium, interferon, and antimalarials.⁴ Systemic corticosteroids, although providing short-term benefit in control of psoriasis, are not recommended. Abrupt discontinuation of the drug commonly exacerbates the disease.

Psychiatric comorbidities such as anxiety and depression may exacerbate psoriasis. Stress is also common trigger of psoriasis.³ Thus, psoriatic patients may benefit from psychological intervention.

Indications for Consultation

Dermatological consultation is indicated when topical medications have not been effective and ultraviolet light or systemic therapy are needed. These therapies include office- or home-based narrow-band ultraviolet B or A light therapy, light therapy with psoralens (PUVA), Goeckerman therapy (light therapy with tar), acitretin, methotrexate, biologics (etanercept, adalimumab, alefacept, infliximab, ustekinumab, golimumab, etc), and cyclosporine.⁸

Pregnant or lactating women with psoriasis should be comanaged by obstetrics and dermatology.⁹

All systemic comorbidities should be monitored and discussed with patients, with consultation to specialists when appropriate as discussed above. Rheumatologic consultation is indicated if signs or symptoms of psoriatic joint disease or enthesitis are present.

Patient Information

• The National Psoriasis Foundation: www.psoriasis.org

• Youth and Parents: www.PsoMe.org

• Arthritis and Psoriasis: www.rheumatology.org

• The Arthritis Foundation: www.arthritis.org

• National Institute of Arthritis and Musculoskeletal and Skin Diseases Information Clearinghouse: www.niams.nih.gov

Introduction

Seborrheic dermatitis is a common skin disorder that involves the scalp and other areas of high sebaceous gland activity such as the central face and chest. It can present at any age, but its peak incidence occurs in infants and in middle-aged adults. Seborrheic dermatitis is more prevalent and more severe in patients with acquired immunodeficiency syndrome (AIDS) and neurological disorders.

Pathophysiology

Etiology is dependent on 3 factors, sebum, Malassezia yeast, and individual susceptibility. Recent work has revealed that Malassezia globosa and Malassezia restricta predominate and oleic acid alone can initiate dandruff-like desquamation.¹⁰

Clinical Presentation

History

The patient typically complains of a dry, scaly or flaky, itchy scalp.

Physical Examination

Infants usually present with "cradle cap," pink to yellow macules, and patches with white greasy scales on the scalp. The face, trunk, and diaper areas may also be affected. Adolescents and adults also present with scalp involvement most commonly with "dandruff," white flakes with no erythema (Figure 9-7). Moderate to severe seborrheic dermatitis is characterized by erythematous plaques with white greasy scales. It may involve the forehead, eye brows, eyelash line, nasolabial folds, and ears (Figure 9-8) and less commonly the upper chest and intertriginous areas.

Laboratory Findings

Skin biopsies are usually not diagnostic and are only helpful to rule out other disorders.

Diagnosis

The key diagnostic clinical features of seborrheic dermatitis are pink plaques with fine greasy white scale on the scalp, eyebrows, nasolabial fold, and ears.

Differential Diagnosis

• ✓ The differential diagnosis includes other papulosquamous diseases (Table 9-1).

• ✓ Atopic dermatitis: Atopic children and to some degree adults may have scaly lesions in the scalp; however, they usually have areas of involvement on the extremities, particularly in the flexural regions.

• ✓ Tinea capitis: Trichophyton tonsurans fungal infections in children, especially in African American children, may be indistinguishable from seborrheic dermatitis. Fungal cultures or potassium hydroxide (KOH) examinations are needed to clarify the diagnosis.

• ✓ Other common diseases include rosacea and contact dermatitis.

• ✓ Uncommon diseases: Dermatomyositis and Langer-hans cell histiocytosis (children).

Management

• Mild scalp seborrheic dermatitis can usually be controlled with over-the-counter shampoos containing zinc pyrithione (Head and Shoulders), selenium sulfide (Selsun), coal tar (Neutrogena T-Gel), salicylic acid (Neutrogena T-Sal), or ketoconazole (Nizoral A-D). Patients should be instructed to shampoo 3 to 5 times a week.

• Moderate to severe scalp disease can be treated with prescription shampoos that contain selenium sulfide 2.5% (Selsun), ketoconazole (Nizoral) 2%, fluocinolone acetonide 0.01% (Capex), or clobetasol (Clobex) 0.05%. Topical steroid solutions such as fluocinonide 0.05% can be used sparingly twice a day.¹¹

• Facial involvement can be managed with sparing use of hydrocortisone 1% cream daily and/or topical antifungal agents such as clotrimazole 1% cream, miconazole 2% cream, and ketoconazole 2% cream. Tacrolimus ointment and pimecrolimus cream are commonly used for facial disease. However, they only are FDA approved for use in atopic dermatitis.^6,11

Seborrheic dermatitis usually responds well to treatment, but it is a chronic condition requiring long-term therapy.

Indications for Consultation

Severe or persistent disease that does not respond to treatment, especially in children in whom the presence of persistent seborrheic dermatitis could indicate more serious underlying disease.

Patient Information

PubMed Health: www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001959/

Introduction

Pityriasis rosea is an acute, self-limited papulosquamous exanthem that, generally, lasts between 6 and 8 weeks (average 45 days), resolving on its own. Cases are frequently noted in clusters, with no seasonal preference. Patients are typically young adults, average age at presentation is 10 to 35 years, and females are slightly more affected (1.5:1).¹²

Pathophysiology

The etiology of pityriasis rosea remains an area of debate. Several factors suggest an infectious agent based on clustering of cases, self-limited nature, and rare recurrences. The current proposed pathogen is human herpes virus (HHV)-6 and/or HHV-7 with either a reactivation or primary infection.^12,13 Some support for this theory has come from the increased incidence in pregnancy, a relative immunosuppressed state, as well as studies identifying HHV-6 and HHV-7 using polymerase chain reaction (PCR) in affected individual's skin. Pregnant women who develop pityriasis rosea within 15 weeks of gestation may have an active HHV-6 infection and may have a premature delivery with neonatal hypotonia or even fetal death.¹²

Clinical Presentation

History

The most commonly reported symptom is itch. Occasionally a viral-like constitutional prodrome or symptoms of an upper respiratory infection may precede the onset of cutaneous lesions.

Physical Examination

Pityriasis rosea typically presents initially with a single herald patch, which is a pink-salmon-colored, oval, 2 to 10 cm plaque with central fine collarette scale (Figure 9-9).

The subsequent lesions are smaller (1-2 cm) pink-salmon-colored papules and plaques on the trunk and extremities. They also have fine central or a collarette of scale. They typically develop in the lines of cleavage (Langer's), symmetrically, and result in a "Christmas tree" distribution. The face, scalp, hands, and feet are usually spared. Lymphadenopathy may be present. Pigmented skin alters the color of lesions with a violet-gray color spectrum as opposed to pink. It is more common to see involvement on the head in darker pigmented individuals as well.

Reported variants include papular, vesicular, urticarial, purpuric, inverse pityriasis rosea, and absent or numerous herald patches.

Laboratory Findings

As pityriasis rosea is a clinical diagnosis made by history and physical examination, laboratory studies are usually unnecessary. However, if there is diagnostic uncertainty, a skin biopsy or a KOH scraping should be done to aid in the diagnosis. A rapid plasma regain (RPR) should be done in any patient at risk for syphilis.

Diagnosis

The key diagnostic clinical features of pityriasis rosea are an initial herald patch, an oval plaque with a collarette (scale) followed by a symmetric, secondary eruption in a "Christmas tree" pattern.

Differential Diagnosis

• ✓ The differential diagnosis includes other papulosquamous diseases (Table 9-1).

• ✓ Drug-related eruptions: Barbiturates, captopril, clonidine, metronidazole, penicillamine, isotretinoin, levamisole, NSAIDs, omeprazole, and terbinafine.

• ✓ Vaccine-related eruptions: A handful of vaccinations have rare reported occurrences of pityriasis rosea like eruptions; these include diphtheria, pneumococcal, hepatitis B, BCG, and smallpox.

• ✓ Other: Viral exanthems, pityriasis lichenoides chronicus, lichen planus, and erythema dyschromicans perstans.

Management

As pityriasis rosea is a self-healing, self-limited benign eruption, treatment is not required. The most important "intervention" is patient education and reassurance. The diffuse, rapid eruption is often disconcerting to patients and parents. In fact, a study on the impact of PR on quality of life showed that concerns of etiology and infectivity had greater impact than rash severity.¹⁴ Reassurance of the self-limited, noncontagious nature of the eruption is important.

Additionally, no treatments can be recommended on the basis of evidence-based medicine. A recent Cochrane review showed insufficient evidence for nearly all interventions such as emollients, topical antihistamines, steroids, light therapy, and antimicrobials.¹⁵ Based on the proposed correlation with HHV-6 and HHV-7 acyclovir has been studied at both high and low doses, but is not commonly used.¹²

If treatment is needed, it is empiric and focuses on symptomatic relief, namely, controlling pruritus.^12,13 Regular application of emollients can be helpful. Lotions with camphor, menthol, pramoxine, or oatmeal could provide added antipruritic benefit. Use of sedating (diphenhydramine, hydroxyzine) and nonsedating (cetirizine) antihistamines can also provide relief. Medium-potency topical steroids, such as triamcinolone or fluocinonide, may provide an additional antipruritic benefit as well as improve the inflamed appearance of lesions. In more severe or recalcitrant disease systemic steroids may be considered. Phototherapy (usually narrow-band UVB) may provide symptomatic relief, but requires a referral to a treatment center, and has not been shown to decrease the duration of disease.

Indications for Consultation

Severe or nonresolving case with recalcitrant pruritus. Additionally, in light of the recent question of obstetric complications a referral for pregnant patients to maternal fetal medicine or alerting the patient's obstetrician may be prudent.¹²

Patient Information

• PubMed Health: www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001874/

• AFP Review Handout: www.aafp.org/afp/2004/0101/p94.html

Introduction

Lichen planus is an uncommon papulosquamous skin disorder. It affects all age groups but is most common between the ages of 30 and 60.¹⁶ Children and infants are not commonly affected. There are no gender or racial predispositions.

Pathophysiology

Lichen planus is thought to occur as a result of an immune dysfunction with altered surface keratinocyte antigen presentation and subsequent cytotoxic T-cell reaction.¹⁷ A genetic susceptibility has been proposed. The skin eruption has been associated with systemic drugs and hepatitis C virus, but a definitive cause has not been identified. Common drugs linked to lichen planus are gold, antibiotics, diuretics, and antimalarials.

Clinical Presentation

History

Patients usually present with a complaint of itching and onset of red bumps. The pruritus can range from mild to severe with an occasional patient having no symptoms. If LP affects the mouth, symptoms such as burning or stinging on exposure to hot or spicy foods is sometimes elicited.

Physical Examination

The primary lesions of lichen planus are violaceous flat-topped firm papules (Figure 9-10). These may be scaly, and round or polygonal in shape. The lesions are distributed symmetrically, typically on the flexor wrists, forearms, ankles, lower back, and genitals. Mucous membrane lichen planus is often present and appears as net-like white streaks on the buccal mucosa (Wickham striae) (Figure 38-28). Oral ulceration may be present. Scalp lesions with a scarring alopecia may be the only manifestation of the disease. A unique feature of lichen planus is its ability to Koebnerize (Figure 9-11). This phenomenon is triggered by trauma, with resultant lichen planus observed in the area of injury. Sometimes generalized and localized hypertrophic forms occur. Hypertrophic lichen planus most often involves the anterior shins and the papulonodules show marked hyperkeratosis.

Laboratory Findings

The most useful diagnostic test is a skin biopsy. The biopsy shows a uniform band-like lymphocytic infiltrate at the base of the epidermis. In some instances the histologic finding can suggest drug-induced lichen planus.¹⁶

Diagnosis

The key diagnostic clinical features of lichen planus are pruritic flat-topped papules on the flexor areas, lower back, and ankles.

Differential Diagnosis

• ✓ The differential diagnosis includes other papulosquamous diseases (Table 9-1).

• ✓ Scabies: Presents with tiny excoriated papules and/or vesicles in many of the same areas as lichen planus.

• ✓ Lichenoid drug rash: May be indistinguishable from lichen planus.

Management

Removal of the offending agent is the first step, if one is identified. Drug-induced lichen planus and hepatitis C are common conditions that may present with a lichenoid skin eruption.^16,18 Lichen planus can be treated with medium-potency corticosteroids applied to the affected area 1 to 3 times daily.¹⁸ When the eruption is controlled, the frequency of drug use can be reduced or eliminated. If corticosteroids are used for prolonged periods, care must be taken to avoid drug-induced secondary changes such as atrophy.

Indications for Consultation

Unusual presentations or widespread distribution of a lichenoid eruption should be considered for consultation. Additionally, moderate to severe oral disease may require consultation with a specialist.

Patient Information

• Lichen Planus Support Group: www.mdjunction.com/lichen-planus

• American Academy of Dermatology: www.aad.org/skin-conditions/dermatology